SBO project IWT Derde jaarlijks rapport

Faculteit Toegepaste Wetenschappen Departement Burgerlijke Bouwkunde Laboratorium Bouwfysica Kasteelpark Arenberg 40, 3001 Heverlee Universiteit Gent Vakgroep Mechanica van Stroming, Warmte en Verbranding Sint-Pietersnieuwstraat 41, 9000 Gent Universiteit Gent Vakgroep Architectuur en Stedenbouw Plateaustraat 22, 9000 Gent Technische Universiteit Eindhoven Unit Building Physics & Systems P.O. Box 513, 5600 Eindhoven Wetenschappelijk en Technisch Centrum voor het Bouwbedrijf Departement Geotechniek en Structuren Departement Bouwfysica en Uitrustingen Poincarélaan 79, 1060 Brussel Physibel Heirweg 21, 9990 Maldegem

Daidalos Bouwfysisch Ingenieursbureau Oudebaan 391, 3000 Leuven

Ingenieursbureau Stockman nv Muinklaan 6, 9000 Gent

Heat, air and moisture performance engineering A whole building approach SBO project IWT 050154 Derde jaarlijks rapport Staf ROELS, Erik DICK, Michel DE PAEPE, Arnold JANSSENS, Peter WOUTERS, Benoit PARMENTIER, Xavier LONCOUR, Filip VAN RICKSTAL, Gilles FLAMANT, Luk VANDAELE, Jan HENSEN, Bert BLOCKEN, Piet HOUTHUYS, Piet STANDAERT, Filip DESCAMPS, Piet DELAGAYE, Demir-Ali KÖSE, Kim GOETHALS, Marnix VAN BELLEGHEM, Mohammad MIRSADEGHI, Daniel COSTOLA, Tadiwos ZERIHUN DESTA, Thijs DEFRAEYE (verslag). September 2009

Inhoud Inhoud......................................................................................................................................... 1 1 Wetenschappelijk- technisch verslag ................................................................................. 3 1.1 Overzicht van uitgevoerde activiteiten....................................................................... 3 WP1.1 Wind pressure distribution ..................................................................................... 4 WP1.2 Driving rain load distribution............................................................................... 13 WP2.1 Development of HAM model............................................................................... 17 WP2.2 Experimental analysis on building enclosures ..................................................... 19 WP3.1 Convective heat exchange and summer comfort.................................................. 21 WP3.2 Development of CFD-HAM model...................................................................... 31 WP4 Towards an integrated approach ............................................................................. 36 WP5.1 Strategic and integrated planning of research activities....................................... 43 WP5.2 Strategic implementation of testing and simulation facilities .............................. 45 References ........................................................................................................................ 46 1.2 Bijsturingen in het project ........................................................................................ 47 1.3 Beheer van het project.............................................................................................. 47 1.4 Haalbaarheid van het project.................................................................................... 48 1.5 Te beschermen resultaten ......................................................................................... 48 2 Utilisatieverslag................................................................................................................ 49 2.1 Valorisatiepotentieel: geactualiseerde visie ............................................................. 49 2.2 Overzicht van de uitgevoerde valorisatieacties........................................................ 52 2.3 Bescherming projectresultaten ................................................................................. 58 3 Financieel verslag............................................................................................................. 59 3.1 Prestatietabel ............................................................................................................ 59 3.2 Prognose voor komende projectjaar......................................................................... 60 3.3 Financiële verantwoording....................................................................................... 61

1 Wetenschappelijk- technisch verslag 1.1 Overzicht van uitgevoerde activiteiten Het onderzoekswerk is georganiseerd in vijf werkpakketten, welke op hun beurt nog verder onderverdeeld zijn: WP1 Outside boundary conditions WP1.1 Wind pressure distribution WP1.2 Driving rain load distribution WP2 Building envelope WP2.1 Development of HAM model WP2.2 Experimental analysis on building enclosures WP3 Building interior WP3.1 Convective heat exchange and summer comfort WP3.2 Development of CFD-HAM model WP4 Towards an integrated approach WP4.1 Development of a prototype software environment WP4.2 Development of a coupling necessity decision procedure WP4.3 Experimental validation WP5 Establishment of a knowledge platform WP5.1 Strategic and integrated planning of research activities WP5.2 Strategic implementation of testing and simulation facilities Dit verslag beschrijft de onderzoeksactiviteiten van het derde projectjaar lopende van 1 september 2008 tot 1 september 2009. Dit deel van het verslag is opgemaakt in het Engels omdat dit de voertaal is voor publicaties en wetenschappelijke rapporten en een aantal onderzoekers Nederlands niet als moedertaal hebben.

IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

3

WP1.1 Wind pressure distribution Objectives WP1.1 emphasises the distribution of pressure differences across the building envelope due to wind flow. This subtask is subdivided in two parts: WP1.1.1 Some sets of full-scale measurements will be recorded regarding the wind pressure distribution on the building envelope of the building “WINDHouse” of the Laboratory Structures of BBRI, located in Limelette. The data will be used to asses the numerical predictions with CFD (Computational Fluid Dynamics). WP1.1.2 Numerical simulations of the air flow around a building will be performed. Different hybrid RANS-LES models to describe the turbulence are tested. The calculations will provide, among other numerical results, the pressure distributions at various locations on the building surface. The obtained data will be compared with the experimental pressure data sets provided by WP1.1.1.

Description of work WP1.1.1 Experimental analysis of wind pressure distribution over a building envelope A reliable prediction of the wind pressure around a building is a necessity for a correct simulation of the Heat, Air and Moisture performance of that building. The wind pressures can be calculated with numerical models, they can be determined using scaled models in a wind tunnel or they can be measured on a real scale building. This section describes the measurements that were carried out on the “Windhouse”, situated at the BBRI-site in Limelette. It first describes how the measurements were organised and then discusses the results. The test configuration in Limelette aims to measure the pressure values around the real scale test house that are caused by wind. Figure 1 shows the “Windhouse” building (Parmentier 2003).

Figure 1. The rotary wind house situated on the research site in Limelette.

The locations of the measuring points were determined together with the colleagues from the department of Flow, Heat and Combustion Mechanics from UGent since they will use the results of the experiments to validate their numerical model. The roof contains 6 measuring points, the facades contains 24 points. The measuring points are somewhat concentrated at the front (Figure 2). Because of the ability to rotate the building, this does not limit the amount of IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

4

information that can be read from the tests. In addition to these external pressure taps, the internal pressure in a nearly air tight box inside the house was measured.

Figure 2. The locations of the measuring points in the facade and the roof.

Because pressure values are low when relatively low wind speeds are measured, some uncertainty is expected on the absolute level of the pressures. In order to overcome this problem, the Cp-values should be calculated in a different way. The method used is based on the analysis of the variations of the pressure and wind velocities. A collection of measurements consists of the data obtained from the peripherals: the wind properties and the position of the house and the wind pressure values. Figure 3 shows the pressure history measured at points 19 and 22. The average wind velocity is 5.8 m/s, but the peak velocity is nearly 50% higher. Variations in wind velocity are common. More striking are the variations in the wind direction. The house is rotated in a way that the desired angle of attack of the wind is realised compared to the (average) wind direction measured during the last standby period. However, since the wind direction is seriously varying during the record, the average angle of attack might differ from the aimed one. On a series of 20 runs, the deviation of the angle of attack is as high as 9°. This deviation brings about significant divergence from expected theoretical values. Obviously, the real angle of attack is used for the analysis (and not the supposed one). As stated before, the analysis is based on the variations of the measured pressure values rather than on the absolute pressure. A run contains the wind properties and the pressures caused by the wind load on the house. A measuring run lasts 10 minutes. For each angle of attack, a number of runs is carried out. They are analysed one by one and then the individual results are averaged. The runs are realised on different days and are related to different wind directions. The Cp-value for a point is given by: P Cp = 2 2 v ρ


5

Figure 3. Wind pressure history for a 10 minute run.

This equation is valid for a constant wind velocity. Since the velocity varies during the 10 minutes lasting measurements, one should use an average value. When calculated in the classical way, the average wind velocity would be the average of the mean wind velocity measured by the three anemometers in the middle of the measuring mast. Then, the square of this average velocity is used. The pressure value P that is used is the average of the pressure for a certain point. The density of the air is considered to be 1.2 kg/m3. All the runs for the same angle of attack are averaged to obtain the final result. One should realise that this is not completely correct. One should use the average of the square velocity-values instead of the square of the average velocity. Although the result differs only slightly in case the wind velocity variations are small. Further, one should remember that the results are analysed using the variation of the pressure and wind velocity rather than the absolute values to calculate Cp.

Figure 4. Cp-values corresponding to an angle of attack of 0°, based on pressure and wind velocity variations.

When the wind is blowing perpendicular to the front, there is a 0° angle of attack. The wind causes overpressure on the front and thus positive Cp-values. On all other facades negative Cp-values will be present. In total, 38 runs are carried out. Results are shown in Figure 4. The spread on the results is rather big. This can be explained by the variation on the angle of attack. The most critical points, those located near the front corners, indeed show the biggest variation. When calculated in the classical way, their sign is continuously changing, IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

6

confirming the fact that overpressure is alternating with underpressure. This hinders the comparison of the experiments with the numerical simulations. To get an idea of what might be expected, a simulation with a small angle of attack, say 10°, could be interesting. When the wind is blowing parallel to the front, perpendicular to the façade containing the steps, there is a 90° angle of attack. The measuring points are asymmetrically spread in this case since they are concentrated at one side of the house. Figure 5 provides the results for the 90° angle of attack. Finally, other measurements (not presented here) were achieved for 45° and 180°.

Figure 5. Cp-values corresponding to an angle of attack of 90°, based on pressure and wind velocity variations.

WP1.1.2 Development of a hybrid RANS-LES technique of flow over buildings Motivation of the subtask From a practical point of view it is not feasible to perform high quality Large Eddy Simulations (LES) of flows around buildings (LES = resolving the large turbulence structures in the flow and modelling the small structures). Since anyhow in the vicinity of walls turbulent structures are small, an extreme fine mesh near building walls is required for sufficient resolution. This leads to very large computational costs. On the other hand, simulations with Reynolds Averaged Navier-Stokes equations generally result in very poor predictions of the flow field over a building (RANS = modelling all the turbulence structures). This is due to the large-scale unsteadiness of the flow. A possible solution is a hybrid RANS/LES model. In such a model, an unsteady Reynolds Averaged Navier-Stokes (RANS) model is used in the near-wall regions, while far from walls a sub-grid scale (SGS) model is used within a LES-formulation. The motivation is the belief that turbulence in wall vicinity is reasonably universal, so that RANS description is valid, while far from walls it is not, so that LES description is more appropriate. The hope is that by using RANS in wall vicinity, the grid can be much coarser than necessary for LES, so that sufficient quality of the flow prediction can be obtained at an acceptable computational cost. Obtained results During the first and second project years, many hybrid models have been investigated, including the more-or-less standard Detached Eddy Simulation (DES) model of Spalart, the DES model based on the SST k-ω turbulence model (DES-SST), the k-l model of Davidson, the k-l model of Tucker and the hybrid model developed by our own research group (C. De IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

7

Langhe): the ε-l model. The test case was a wind-tunnel experiment of the flow over a cube on a flat plate. The Reynolds number based on the cube size is 105. This is about a factor 40 lower than for atmospheric boundary layer flow, but it is generally accepted in the community that for this difference in Reynolds number, flow patterns are not much different. The conclusion was that, based on the prediction of velocity profiles, the DES-SST model results are in best agreement with the experimental data, especially in the vicinity of the cube. Therefore, we recommended this hybrid model at the end of year two for the prediction of the pressure distribution on a building. We identified test data for flow over a cubic building of 6 m x 6m x 6 m in real atmospheric conditions. The Reynolds number is 4x106. The pressure distribution is available on two cuts of the cube: one with the vertical symmetry plane in flow direction and one with a horizontal plane. The data were used in year three for further validation of RANS-models, hybrid RANS/LES models and LES models, with the aim to come to a final conclusion on the use of hybrid methods for analysis of flows over buildings. We used two grids. Mesh A is a typical RANS-grid with clustering of nodes in wall vicinity, with approximately 8x105 cells. Mesh B has a little more than 1.2 million cells and is a grid particularly adapted for LES. It has a coarse background grid, which is refined twice in cube vicinity. Both grids are rather coarse, with a size typical for RANS calculations, with the objective to keep computational costs low. At the inlet of the domain a logarithmic velocity profile, derived from the experimental profile, is assumed. We tested RANS, hybrid RANS/LES and LES. The grids are much too coarse for a genuine LES. Therefore, we introduced a wall model to derive the shear stress at walls. We used the best quality wall model of FLUENT (enhanced wall treatment) and an own developed wall model. The results of the hybrid RANS/LES simulations are poor and almost equal to the results of the RANS simulations. The main reason is that the grids are by far not fine enough for reliable simulations with typical hybrid models. These models activate LES when the grid size is small enough to resolve a significant part of the turbulent structures. On very coarse grids, this only happens in limited areas. In our simulations, LES is only active in a very small part in the wake of the building. This is not enough to benefit from the LES features of the model. So, we suffer here a drawback of the much higher Reynolds number with respect to the earlier wind tunnel tests. The grids have about the same size in both applications, but due to the much higher Reynolds number, in real atmospheric conditions, the scale range of the turbulence structures is much larger, so that with the used grid size we only resolve but the very largest turbulence structures. As a consequence, the hybrid algorithm decides to stay in RANS mode almost everywhere. Much better results are obtained by forcing LES to be active everywhere. Principally, this is not justified due to the coarseness of the grid. So, it means that we perform underresolved LES. Due to the coarse grid near walls, a wall model is necessary to determine the wall shear stress. Overall, the results with such a crude LES method are quite good. Summary of the work in year 3 RANS-simulations. We tested the standard k–ε and the k–ω SST models. As expected, the RANS results are poor since the flow is highly unsteady but it is represented steady with the RANS models.


8

Hybrid RANS/LES-simulations. In this case we only tested the DES–SST model. Based on the results of the second project year, we expected that this hybrid model would perform the best. However, we observe that there is hardly any difference between the hybrid model and the k–ω SST predictions. Plotting the relative DES length scale reveals that the LES region is very small and located in the wake of the building. This means that there is very low LES activity and the simulation is RANS in a large vicinity of the building. This explains the resemblance of the RANS and hybrid results. LES-simulations. Here we tested the standard Smagorinsky model with Cs = 0.1. We also ran calculations without a SGS model by putting Cs equal to 0. Furthermore, we derived a wall model (WM) based on the log law and used this instead of the no–slip boundary condition. The WM is programmed with user defined functions (UDF’s) and is used on both grids. Remark that when a no-slip boundary condition is activated in FLUENT, actually on coarse grids also a wall model is used (enhanced wall treatment). The LES simulations are far much better than the hybrid predictions. There is very good agreement with experimental profiles at the front, on the top and at the back of the building. The predictions on the side walls follow the experimental profiles, but there is some deviation. There is also very little influence of the wall model. With our own wall model and the wall model of FLUENT, the results are almost the same on mesh A. On mesh B we observe some differences in particular at the top and side walls of the building. We observe that the overall quality of the predictions is not really better on mesh B than on mesh A. This means that both meshes are much too coarse to resolve enough in wall vicinity. The differences in the results are due to the different mesh size in wall vicinity, but there is no conclusion on the best gridding strategy. The observation is that any LES formulation gives reasonably good results, taking into account the very coarse grids used. Practical conclusion Based on the results of the wind-tunnel experiment, our expectation was that the DES-SST model would again perform the best for the cubical building in the atmospheric boundary layer. This is not what we observe. The results of the hybrid RANS/LES simulations are poor and almost equal to the results of the steady state RANS simulations. The main reason for the poor predictions is that the grids which we use are not fine enough for high quality hybrid simulations. Plotting the relative DES length scale reveals that the LES region is very small and is located in the wake of the building. This means that there is very low LES activity. One could make use of much finer grids. This would lead to better predictions but at a very large computational cost. This is what we try to avoid here. With LES, we observe only little sensitivity to the quality of the predicted pressure distribution from grid resolution in wall vicinity and from the wall stress calculation method. For practical prediction of the pressure distribution on real size buildings, we therefore now have to recommend LES with a wall model.


9

Examples A view of mesh A and mesh B is given in Figure 6. In Figure 7 to Figure 9 we present the prediction of the pressure distributions on both sections and mesh A. Finally, the results for the LES and ILES simulations on mesh B are shown in Figure 10.

Figure 6. Mesh A (left) and close up of mesh B (right).

Figure 7. Pressure coefficient profiles on the vertical (left) and horizontal (right) sections, RANS results on mesh A. Black squares are experiments.

Figure 8. Pressure coefficient profiles on the vertical (left) and horizontal (right) sections, HYBRID results on mesh A. Black squares are experiments.


10

Figure 9. Pressure coefficient profiles on the vertical (left) and horizontal (right) sections, LES and ILES results on mesh A. Black squares are experiments.

Figure 10. Pressure coefficient profiles on the vertical (left) and horizontal (right) sections, LES and ILES results on mesh B. Black squares are experiments.

Deliverables WP1.1.1 • The test setup for the Windhouse has been used to obtain various data sets, which can be used for validation purposes in WP 1.1.2. WP1.1.2 • Several RANS, hybrid and LES techniques were evaluated for a full-scale building in atmospheric conditions. Attention was given to wall modelling and grid quality. LES together with a wall model is recommended for surface pressure and flow calculations around buildings. Planning WP1.1.1 • Further processing of the measured data and transfer of the results to WP 1.1.2. In a technical meeting the agreement of the simulations of WP 1.1.2 and the measurements of WP 1.1.1 will be discussed. WP1.1.2 • In the literature, experimental pressure data on a 13.7 m x 9.1 m x 4 m building with a roof (the Texas Tech experiment) have been found. Measurements have been IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

11

•

performed at angles of attack of 90º and 60º. We will use LES and ILES and compare the results with the available data. At the BBRI, a test building has been built with pressure taps for pressure measurements. We will simulate the flow around this test building and validate it with the experimental data.


12

WP1.2 Driving rain load distribution Objectives WP1.2.1. Laboratory and in situ experiments of contact phenomena of driving rain impinging on different building materials. The final amount of water that may enter the building enclosure (the boundary conditions for the building envelope model) will be determined by splashing effects, adhesion, evaporation, run-off and capillary absorption. All these phenomena strongly depend on the material properties of the building enclosure. Parameters are porosity of the material, moisture capacity, capillary activity, …. WP1.2.2. Development of a water uptake and run-off model for building materials. Numerically, the transformation of individual rain drops, absorbed by the building material towards a smeared wetting as assumed in building envelope models, will be investigated. In addition, a run-off model for rain water run-off on capillary active materials will be developed. The research of the previous two sections of this subtask (WP 1.2.1 and WP1.2.2) was conducted in strong collaboration with a PhD student working on a KUL OT-project where the contact phenomena (bouncing, splashing and spreading) and surface phenomena (absorption, evaporation and run-off) are also of interest. Out of this research it has become clear that the outside boundary conditions, namely convection and radiation, have a large impact on the evaporation at building facades wetted by wind-driven rain. Therefore the focus of the PhD student that is involved in this SBO project (PhD1) will be mainly on these topics and an additional subtask (WP1.2.3) has been introduced below. WP1.2.3. Numerical and experimental analysis of convective heat and mass transfer at exterior building surfaces. More accurate predictions of the convective transfer coefficients are obtained, considering the influence of wind speed, wind direction and building surroundings and spatial distribution across the surface. Also the influence of specific materials and surface texture is investigated.

Description of work WP1.2.1. Laboratory and in situ experiments of contact phenomena of driving rain impinging on different building materials. The objectives of this subpackage are achieved. No further actions are planned for the coming year. WP1.2.2. Development of a water uptake and run-off model for building materials. The objectives of this subpackage are achieved. No further actions are planned for the coming year. WP1.2.3 Laboratory experiments and numerical modelling of the influence of outside boundary conditions on the heat and mass transfer at building facades wetted by wind-driven rain. As mentioned before, the effect of the outside boundary conditions, such as convection and radiation, was found to be of significant importance in the assessment of the response of building walls after a rain event for simulations such as described in WP1.2.2. Therefore, WP1.2.3 was created. In a first stadium, only convective heat and moisture transfer was considered and only forced convection was taken into account. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

13

The numerical study (with CFD) on convective heat transfer of an isolated cubic building in an atmospheric boundary layer was continued. The focus was mainly on boundary-layer modelling issues. Two different techniques were considered: (1) low-Reynolds number modelling (LRNM), which was found to give accurate CHTC predictions but which required a large computational grid in the boundary-layer region; and (2) wall functions (WF), which are less accurate in predicting heat transfer in the boundary layer but which allow for much coarser grids and therefore these WF are commonly used in building aerodynamics. Two optimisation approaches are proposed to allow for accurate convective heat transfer predictions with CFD (RANS) without increasing the computational cost significantly. The first approach considers evaluating convective heat transfer at lower wind speeds, based on the concept of flow similarity by Reynolds number independence. Afterwards the obtained data at these low wind speeds are successfully extrapolated to higher wind speeds. The advantage of using low wind speeds in the simulations is that it leads to a reduction of the computational grid resolution in the boundary-layer region. A significant reduction of the wind speed, used in the simulations, was found to be possible, up to a factor of about 5, depending on the conditions. The second approach proposed the use of customised thermal wall functions (CWF), derived from LRNM simulations. These wall functions showed a significant improvement of heat transfer predictions compared to standard wall functions (SWF) but still allowed for coarse grids in the boundary-layer region (see Figure 11). Note that two journal papers on this work will be submitted soon to international journals.

3

120 100 80 60

2

y* [-]

4

x

40

1

0

Wind

20

(a)

0

0 0.5

1

5 CHTC [W/m²K]

140

CHTC - LRNM CHTC - SWF CHTC - CWF y* - CWF

1.5 x/H [-]

2

2.5

3 140

CHTC - LRNM CHTC - SWF CHTC - CWF y* - CWF

4 3

120 100 80 60

2

y* [-]

CHTC [W/m²K]

5

x

40 1

(b)

0 0

20

Wind

0 0.5

1

1.5 x/H [-]

2

2.5

3

Figure 11. Convective heat transfer coefficient (CHTC) distribution on the surfaces of a 10 m high cubic building (for LRNM, SWF and CWF) and distribution of y* in the wall-adjacent cell (for CWF) in a vertical (a) and horizontal (b) centreplane for a reference wind speed of 0.5 m/s at a height of 10 m.

In the previous simulations, heat transfer is entirely solved within the CFD package. Solving moisture transfer in porous materials (which involves both liquid and vapour transport) is not possible with the CFD software that is used. Therefore the program is coupled (explicitly) with HAMFEM, which is an in-house HAM modelling tool developed by the Laboratory of


14

Building Physics. The air flow is entirely solved within the CFD package whereas the heat and moisture transport in the porous material is solved within HAMFEM.

Symmetry (slip wall)

Ground (AD&IP&NS)

7H

20H

9 cm

Inner wall (not included in model)

Interface x

Interface

XPS (not included in model)

9.8 m

y

10 m (H)

20H

Building walls (AD&IP&NS)

(b)

Outer wall

U10 = 2.5 m/s Te = 10°C RHe = 60%

Zero static pressure

(a)

Interior boundaries model (AD&IP)

This coupled program (CHAM) is used to evaluate coupled convective heat and moisture transfer for flow parallel to a porous building material. The influence of the air flow on the heat and moisture flows in the porous material is found to be limited if the material is not very wet. This is due to the resistance of the material itself to moisture transport, which is usually much higher than that of the boundary layer. For wet materials however (e.g. after a rain event), a significant difference in drying rate is found with the conventional approach, with spatial and temporal varying transfer coefficients over the surface. This study shows that the use of constant (spatial and temporal) transfer coefficients can lead to a significant simplification of the drying behaviour of porous materials. As a realistic case study, the drying of a building wall, in an atmospheric boundary layer and wetted by wind-driven rain, was also modelled with the coupled model (Figure 12 and Figure 13).

Figure 12. Model for numerical analysis with boundary conditions: (a) Environment modelled with CFD, (b) Wall composition (AD = adiabatic, IP = impermeable for moisture, NS = no-slip wall with zero roughness) (Fig. not to scale). 5.E-05

CHAM - y=9.8m CHAM - y=7.5m CHAM - y=5m CHAM - y=1m CHAM - Average HAM

qc,m,w (kg/sm²)

4.E-05

(b)

3.E-05

2.E-05

1.E-05

(a) 0.E+00 0

1

2

3

4

5 6 7 Time (h)

8

9 10 11 12

Figure 13. Comparison between HAM and CHAM at different positions on the exterior wall surface: (a) Drying rate, (b) RH (%) distribution (with CHAM) over exterior wall surface as a function of time and location on surface.


15

Deliverables WP1.2.1 • The objectives are achieved WP1.2.2 • The objectives are achieved WP1.2.3 • Two optimisation approaches are proposed and evaluated to increase the computational economy for CFD simulations of convective heat transfer calculations at high Reynolds numbers. • The coupled CFD-HAM model was used to calculate drying of porous materials for different configurations.

Planning WP1.2.1 • No further actions are planned for the coming year. WP1.2.2 • No further actions are planned for the coming year. WP1.2.3 • More advanced modelling techniques (e.g. LES) will be evaluated for the isolated building. • The coupled CFD-HAM model will be further verified and validated and applied to various configurations.


16

WP2.1 Development of HAM model Objectives The aim of this subtask is to develop a comprehensive building envelope model for the coupled analysis of heat, air and moisture transport through building enclosures. The model will be based on existing scientific models available from the partners. Because of the different time-scales between heat, moisture and air transport, and the associated numerical obstacles, a stabilised solution method could not be achieved when dealing with air transport. Therefore the main objective of this subtask is to tackle this problem.

Description of work The heat and moisture transfer phenomena through the VLIET test wall in the NE-façade of the row house are modeled using Delphine 5.6.1 software. Boundary conditions are obtained from the experiments. The moisture content of the Celit3D board (the hygroscopic buffering external wind barrier) has been measured on a regular basis on nine removable specimens (see Figure 14). The evolution of the moisture content with time is simulated and compared with the measured data.

Figure 14. The removable Celit3D samples configuration and cross-sectional view of the test wall (right, central and left from the room inside view).

The HAM-response of the walls is simulated for the period from December 2007 until July 2009 with time stepping of one hour. The model is validated in terms of temperature and humidity prediction at several sensor locations. The obtained results show a good prediction of the flow system. Figure 15 compares the predicted moisture content of the Celit3D specimen with the measured data. As can be seen, the simulation underestimates the moisture content of the Celit3D material in the winter season because liquid water transport, a phenomenon occurring due to interstitial condensation, is not yet included in the model.


17

Figure 15. Comparison of simulated and measured moisture content at the left-middle section of the wall.

Deliverables •

The modeling of the HAM-transport is ongoing. The first results are promising, but so far air transport is not the dominant factor.

Planning •

Inclusion of air transport in the model.


18

WP2.2 Experimental analysis on building enclosures Objectives This subtask focuses on the analysis of HAM transport through building enclosures based on measurement data. It was decided to limit the experimental analysis of this workpackage to the VLIET building of KULeuven. The experiments are conducted in a wall of the row house constructed in the previous years (see the report of 2007). The obtained data can be used to get physical insight about the HAM transport phenomena and as a validation tool for the numerical model to be developed under WP2.1.

Description of work To study HAM-transport through building components a test set-up has been constructed at the VLIET building, as mentioned in the previous annual reports. The test set-up consists of a terraced house with in the north-east façade a light weight wooden wall structure partitioned in three parts, each with a similar set-up but different air tightness. In the room, a forced ventilation system is operational, since March 2009. The measurement data are not only used for studying the HAM-flow phenomena through the wall but also to validate a numerical model. In this subsection the experimental results of the VLIET test wall will be analysed and interpreted. Figure 16 shows the evolution of the moisture content of the nine removable moisture capturing Celit3D specimen with time. From March 2009, a forced ventilation system is installed in order to study the effect of air on the prevailing heat, air and moisture transport through the wall (see Figure 17).

Figure 16. Moisture content evolution of Celit3D specimens from June 2008 until July 2009.

To quantify the air tightness of the left, central and right parts of the wall, a tracer gas experiment was conducted. While Sulphur Hexafluoride, a tracer gas, was injected in the room, the injection rate and the gas concentration in the room were recorded. Simultaneously, the concentrations in the cavities, just in front of the three partition of the test wall are logged (Figure 18).


19

Figure 17. a) Ventilation system

b) Room pressure build-up c) Incoming air flow rate.

Based on the mass balance equation of the tracer gas, the air permeability of the left, central and right parts of the wall are deduced as 0.0098, 0.0028 and 0.0054 m3/m2/h/Pa respectively. The conclusion of the results was that all three parts of the wall are at the moment too air tight and air flow effects do not prevail. Therefore at the start of autumn 2009 a grid of small holes will be drilled in the Celit3D to create a diffuse air-open wind barrier.

Figure 18. Tracer gas concentration profile in the room and in front of the three parts of the wall (in the cavity).

Deliverables • • • • • •

Temperature and humidity experimental data are available since December 2007. Moisture evolution data of the celit3D material are collected since June 2008. Tracer gas and ventilation data are available. Data processing tools are developed. Some material property data of Celit3D are available. An internal report that describes experimental analysis and result interpretation is available.

Planning • •

The wooden finishing at the left part of the wall will be drilled in order to study the effect of air flow through it. Measurement of material properties will be conducted.


20

WP3.1 Convective heat exchange and summer comfort Objectives WP3.1 will focus on the convective heat transfer in rooms and offices and its impact on summer comfort performances by solar processing, intensive (night) ventilation and thermally active flooring. Engineering the summer comfort performances depends on the other hand to a large extent on a reliable prediction of the local heating through solar irradiation and the prediction of wind pressures around buildings for ventilation (WP1.1). WP3.1 is subdivided into four parts: WP3.1.1 An experimental analysis of convective heat transfer between the ventilation air and the building surface will be performed. This work focuses on a single zone and will be done in the rotating PASLINK-cell available at BBRI, a highly instrumented test facility. WP3.1.2 An experimental analysis of solar heating and intensive ventilation and its impact on summer comfort will be conducted. WP3.1.3 A numerical prediction of ventilation and local heating through solar irradiation inside buildings will be performed. The solar illuminated patterns on inside surfaces through direct solar radiation will be calculated and converted to local heat powers. For the ventilation, input data from WP1.1 will serve as boundary conditions. The CFD simulations will be coupled with a multi-zone building simulation model and the predictions will be validated by comparison with the test results. WP3.1.4 The numerical methods that are developed will be validated with data measured in projects realised by the industrial partners.

Description of work WP3.1.1 Experimental analysis of convective heat transfer between the ventilation air and the building surface High computational costs and the need of considerable empiricism limit the use of computational fluid dynamics (CFD) in building design, in favour of multi-zone energy simulation (ES). Yet, a key parameter of building performance analysis is the prediction of interior convective heat transfer – as shown in Goethals and Janssens (2008). This study showed that the choice of the convection algorithm is of the same importance as the choice of the design parameters, such as internal heat gains or sun blind control. However, this last finding is predetermined by, amongst others, the modelling of the incoming direct solar radiation, since most of the convection algorithms depend, partially, on the temperature difference between the air and the surface. Therefore, the above-mentioned study is extended to assess the sensitivity of the predicted convective heat transfer, and thus building performance, by ES to the modelling of the distribution of solar radiation – described in Goethals and Janssens (2009a). Simulations of summer comfort in a night-cooled office room in Belgium are carried out in TRNSYS using three convection algorithms and four methods to model the distribution of direct solar radiation. The influence is evaluated for the summer comfort - weighted temperature excess method (GTO) and adaptive temperature limits indicator (ATG) - and the cooling demand with and without night ventilation. To model the distribution of direct radiation, TRNSYS uses, by default, absorptance-weighted area ratios. Conversely, constant fractions of the total entering solar radiation that strikes the surfaces can be defined. Finally, the distribution can also be calculated, based on the position of the sun, IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

21

using uniform or discretized surfaces. In case of discretized surfaces, the movement of the sun patches along the surfaces is modelled in a more detailed way. As shown in Table 1, Table 2, Table 3, the influence of the modelling of the distribution of solar radiation on the predicted thermal comfort and energy demand is inferior to the choice of the convection correlations. However, the relative importance of advanced modelling of the convective heat transfer and of the incoming direct solar radiation is case-specific. Table 1. Results of building simulation with CHTC correlations of prEN ISO 13791.

Incoming radiation

solar

Diffuse radiation Constant Time-dependentuniform Time-dependentdiscretized

GTO (h) 53.40 45.19 (85%) 45.39 (85%) 49.48 (93%)

ATG (h) 0 0

-C 0 0

-B 6 61

A 439 624

+B 234 208

+C 128 79

192 81

0

0

52

639

212

72

78

0

0

55

604

217

94

83

cooling demand (kWh/m².year) AC AC+NV 13.17 2.40 13.21 2.41 (100%) (100%) 13.36 2.48 (101%) (103%) 13.67 2.46 (104%) (103%)

Table 2. Results of building simulation with CHTC correlations of Awbi and Hatton-natural.

Incoming radiation

solar


GTO (h) 115.39 116.53 (101%) 116.39 (101%) 126.29 (109%)

ATG (h) 0 0

-C 0 0

-B 62 62

A 435 435

+B 241 237

+C 115 117

200 202

0

0

61

446

231

130

185

0

0

56

432

224

128

213


Table 3. Results of building simulation with CHTC correlations of Beausoleil-Morrison.

Incoming radiation

solar


GTO (h) 52.23 53.40 (102%) 52.08 (100%) 47.45 (91%)

ATG (h) 0 0

-C 0 0

-B 6 6

A 488 493

+B 243 234

+C 123 128

193 192

0

0

6

474

252

121

200

0

0

4

449

264

141

195


To elaborate on the impact of the modelling of incoming direct radiation, simulations of summer comfort in an office room in the Unilin Flooring-Quickstep building are performed using TRNSYS and VOLTRA. Using the measurement data obtained in the summer of 2009, both simulation models are validated. Given the accuracy of the temperature sensors, the predicted operative temperature corresponds considerably well with the measurement data - as shown in Figure 19. Besides, since the time-invariant convective heat transfer coefficients mentioned in prEN ISO 13791, are used, the importance of the modelling of convective heat transfer should be mitigated - for this specific case at least. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

22

Deviation [°C]

Occurrence [%]

±0.1

17.97

±0.2

28.52

±0.3

39.71

±0.4

56.25

±0.5

63.93

±0.6

70.44

±0.7

75.39

±0.8

79.30

±0.9

82.42

±1.0

86.59

Figure 19. Comparison of measured and predicted operative temperature in the small office.

Hereafter, the impact of the approximation methods used in TRNSYS to model direct solar radiation is compared with the results obtained with VOLTRA, which is equipped with a solar processor. The best agreement is found for the time-dependent distribution of the solar radiation. Especially, the total absorbed solar radiation predicted by the simulation model with discretized surfaces comes close to the VOLTRA results - as shown in Figure 20. Further, a sensitivity analysis, similar to the above-mentioned study, is performed, resulting in similar conclusions.

Figure 20. Comparison of absorbed total solar radiation predicted by TRNSYS (time-dependent, discretized surfaces) and VOLTRA.

Finally, following the research on diffuser modelling in CFD (Goethals and Janssens 2009b), the applicability of correlations for a range of flow regimes will be studied. These simulations are based again on the work performed during the IEA Annex 20-project. For a given Reynolds number, results will be obtained in the range of Richardson number 0≤Ri≤10 and a fixed Prandtl number of 0.71. Correlations, extracted from literature, will be compared with the predicted CHTC values. Beforehand, however, CFD simulations of the two-dimensional case used in Annex 20 are performed to assess appropriate turbulence models. Furthermore, IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

23

the research will be extended with different configurations of inlet and outlet to optimize the design of night ventilation. Currently, however, no agreement between the CFD results and the experimental data is found yet. WP3.1.2 Experimental analysis of solar heating and intensive ventilation and its impact on summer comfort The experimental study will be performed in the PASLINK cells at Limelette. The results and conclusions drawn from this will provide necessary information for multi-zone models. During the last months, one PASLINK test cell, located at BBRI in Limelette, has been adapted into a testing infrastructure allowing a detailed monitoring aiming to a better understanding of the convective heat transfer between the ventilation air and the building surface. Originally the test cell was used to determine the thermal and solar properties of building facade components under real weather conditions in a highly standardised environment. A PASLINK test cell is basically a prefabricated, well-insulated structure, including a service room and a test room. The test room is equipped with both heating and cooling systems that allow the precise control of the indoor climate based on test schemes designed according to the component type. The PASLINK test site is equipped with a meteorological data acquisition system, continuously monitoring the outdoor climate (solar and long-wave irradiance, air temperature, relative humidity, etc.) and the indoor climate in the test cell. A full description of the original PASLINK test cell is available on www.paslink.org. As the ventilation unit is located in the original test room, a well-insulated wall has been constructed in the test room creating a second service room – which comprises the ventilation unit – and a new test room – as shown in Figure 21. By this, the geometrical characteristics of the test room are made simpler and the air inlet and outlet can be created more easily. The separation wall is made of 200 mm EPS and is well-sealed at all joints and borders in order to assure maximum air tightness. To be able to enter the new test room, an ‘openable’ element (door) is created in the separation wall.

Figure 21. Plan of the modified configuration of the PASLINK test cell .

Meanwhile, in the upper part of the wall, at 200 mm from the ceiling, two openings are foreseen, as shown in Figure 22 : one in the symmetry plane and one at 200 mm from the right side wall – seen from inside the test room. At the lower part of the wall, one opening in the symmetry plane is located at 200 mm above the floor. Each opening can be used as an extraction opening, as an inlet or can be closed. In the closed position, the opening is filled with an EPS block, which is perfectly sealed at the edges. In case of an extract or inlet, a grille diffuser, Trox Type AT-DG/225mmx125mm/A1, is installed in the opening. This type of diffuser is chosen because it can be used to study both displacement and mixing ventilation. Moreover, this simple type can be modelled with both the momentum and box model, i.e. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

24

simplified geometry descriptions to be used in CFD. The horizontal aerofoil blades are adjusted to a horizontal position. When the grille is used as an inlet, it is connected by an insulated duct with the fan exit. Moreover, a flow straightener, in front of the inlet grille, has been installed to obtain a representative, symmetric flow – as shown in Figure 23. In case of an extract, the air is sucked from the test room into service room 2 via an identical grille.

Figure 22. Location of the openings in the separation wall.

Figure 23. Detailed view of the grille located in the separation wall and of the flow straightener.

The measurement bay – where normally the façade component to be tested is installed – is filled with a well-insulated wooden frame construction. The wall is a copy of the current side walls and is equipped with a heating foil in order to be able to create a constant surface temperature. Meanwhile, in the test room the air temperature is measured at different positions by thermocouples type T (Co-Cu). As shown in Figure 24, in zone 2 and 4 of the test room, sensors are fixed on a vertical rope at three heights: at 200 mm above the floor, at mid height and at 200 mm from the ceiling. In zone 3, more detailed temperature profiles over the height of the room are measured: one sensor at mid height, four in the lower part at 20 mm, 40 mm, 100 mm and 200 mm from the floor and analogously in the upper part. In all zones, the above-mentioned configurations are installed at three horizontal locations: 150 mm away from the side walls and in-between. Also the air temperature at the inlet grille is measured by a thermocouple. Meanwhile, thermocouples, installed at the surface of the walls, measure the average surface temperature for a whole zone of a specific wall, corresponding to the zones defined in Figure 24.


25

Figure 24. Location of the sensors for the measurement of the air temperature and illustration of the vertical ropes.

Preliminary measurements have been carried out to check the airflow rates given a welldefined supply temperature: an air change rate of 1.53h-1 and 8h-1 and a supply temperature of 15°C while keeping the surface temperature of the wall constant at 20°C or 45°C. Finally, the air velocity profile near the grille has been measured for an air change rate of 8h-1 and a supply temperature of 15°C. However, the measured velocity profiles showed a strong asymmetric character – as shown in Figure 25. Therefore, a flow straightener has been incorporated. Further measurements are regarded necessary.

Figure 25. Velocity profile at a distance x=0.6m away from the grille for three horizontal locations z.

WP3.1.3 Numerical prediction of ventilation and local heating through solar irradiation inside buildings On the measurement equipment built in 2008 an outdoor experiment was carried out in August 2008 and September 2009. The 5-day measurement period from 24 until 28 September with clear sky and still wind conditions was selected for the experimental validation with the program VOLTRA with its solar processor. The boundary conditions to be used for the outdoor climate were the ones recorded by the climate station of the Laboratory of Building Physics on the site. However, as no diffuse solar radiation and no infrared sky radiation are recorded on this site, these data were obtained from the climate station at the BBRI in Limelette. This method was validated, for example by a comparison of the global solar radiation recorded at both sites. Generally spoken there is a good correspondence between measured and simulated temperatures. The differences can be IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

26

explained by the simplified empirical convection model, and by the inaccuracy of some of the boundary conditions. For example, VOLTRA uses a constant external (forced) convective surface heat transfer coefficient, while in reality a variable coefficient occurs due to variable wind speed and different orientations. The main conclusion is that the simulation of the transient 3D heat conduction, the infrared and solar radiation, and the convection using the program VOLTRA allows reliable results. A report (document PPB_Voltra_validation_SBO_box.pdf) with a full description of the validation tests (the internal power test carried out in June 2008 and the outdoors test mentioned above) is available. The report contains a detailed description of the box, the material properties as measured and as assumed in the simulation, the complete results (temperature courses for all thermocouple positions, isotherm snapshots and animations).

Site picture

Isotherms at 9h

Horizontal global solar radiation: Heverlee vs Limelette.

Isotherms at 14h

Air (Heverlee) and sky (Limelette) temperature.

Measured and simulated temperatures (3 positions) Figure 26. Test setup information and results. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

27

WP3.1.4 Validation of the numerical methods with data measured in projects realised by the industrial partners Data measured in projects realised by the industrial partners will be used for the validation of the numerical methods for the prediction and optimization of the summer comfort. From July 2008 to September 2009, Daidalos and UGent-A carried out a measurement campaign in the Unilin Flooring-Quickstep building, located in Wielsbeke, Belgium. The outdoor climate is measured at the roof top while the indoor climate is measured in both a north-oriented landscape office and a two-person office at the south – indicated in Figure 27 by respectively (1) and (2) – both located on the second floor.

Figure 27. Plan of third floor of Unilin Flooring-Quickstep building.

Figure 28. Adaptive temperature limits indicator for small office: building/climate type alpha.

In addition to some problems concerning the outdoor climate measurements, the cooled ceiling seemed to malfunction: the surface temperature of the cooled ceiling always approximates to the plenum temperature. Furthermore, the bypass of the heat exchanger did IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

28

not function, implicating too high supply temperatures. Nevertheless, good thermal comfort was guaranteed during the measurement period - as shown in Figure 28. In 2009, additional tracer gas measurements in the small office were performed to derive the ventilation/infiltration rates. As shown in Table 4, the measured results correspond reasonably well with the design values. As for mechanical ventilation, an air change rate of 0.63h-1, i.e. 84m³/h, corresponds to the foreseen air quality level IDA2. Furthermore, the infiltration rate, which corresponds to a v50-value of 20.14m³/(h.m²), approximates to the average result obtained in nine new Belgian apartments in the SENVIVV study (BBRI 1999). This average value also corresponds to the average measured air tightness in 12 office buildings in the United Kingdom (CMHC 2001). Table 4. Results of tracer gas measurements in the small office.

Ventilation/infiltration Mechanical ventilation Natural ventilation Infiltration

Ventilation/infiltration rate (h-1) 0.63 3.46 0.47

Given the correspondence between the design and actual airflow rates, the perceived air quality agrees very well with the foreseen IDA2 – as shown in Figure 29.

Figure 29. Obtained indoor air quality level in the small office.

Deliverables WP3.1.1 • Paper on sensitivity of thermal predictions to the modelling of direct solar radiation entering a zone. WP3.1.2 • The installation of the first PASLINK cell is completed. However, preliminary measurements indicate the need to further adapt the configuration. WP3.1.3 • The 3D solar processor is validated using measurement data obtained from the measuring equipment, which was developed last year. WP3.1.4 • The measurement data of Unilin Flooring-Quickstep building is available and has been analysed. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

29

Planning WP3.1.1 • The test setup of IEA Annex 20-project is again used to assess the uncertainty of the simulation parameters. Therefore, several simulations are performed using, amongst others, different turbulence models, discretization schemes and grid qualities. • The applicability of correlations for a range of flow regimes will be studied. In this research, the case E.2 of IEA Annex 20-project is again simulated using CFD. For a given Reynolds number, results are obtained in the range of Richardson number as 0≤Ri≤10 and a fixed Prandtl number of 0.71. Correlations, extracted from literature, are compared with the predicted CHTC values. • Simulations of the IEA Annex 20-test room are performed for different types of diffusers at several locations. This investigation is performed to optimize the room design for best night ventilation potential. • Based on the experiments in the PASLINK cells available at BBRI, studying the interaction between solar gains, thermal storage and ventilation, the results of dynamic simulations, using experimental and simulated convection algorithms, will be investigated. WP3.1.2 • During the winter of 2009-2010 steady-state experiments will be carried out in order to validate the CFD simulations of 3.1.1. Dynamic experiments will be performed in summer 2010: with and without thermal mass, with and without the outside box. WP3.1.3 • Will be discussed together with the other partners. WP3.1.4 • Will be discussed together with the other partners.


30

WP3.2 Development of CFD-HAM model Objectives In WP3.2, the emphasis goes to a correct and reliable implementation of moisture transport in CFD-calculations. The enrichment of classical CFD to a CFD-HAM model and the formulation of efficient solution strategies by the build in of UDF’s (User Defined Functions) necessitates an in depth study. WP3.2.1 In order to validate the CFD-HAM model, laboratory tests will be performed in a climate chamber where a conditioned air jet enters at the opposite site of a test sample. The flow pattern inside the climate chamber will be measured with a two-dimensional hotwire anemometer. Velocities near the wall and test sample are again measured with the hotwire anemometer. Temperature and relative humidity inside and around the test sample are also measured. This information is used to determine the convective transfer coefficients. The experiments consist in the moistening (drying) of samples by moist (dry) air. WP3.2.2 A HAM-model will be developed in the CFD-environment. Current state of the art CFD does not offer the possibility to describe the interaction between fluid and solid material for complex geometries in an efficient and satisfying manner. In these cases, the boundary layer problem can only be solved using very fine grids leading to unreasonably high calculation times. Therefore in this project adequate models using UDF’s will be developed and implemented in CFD: i.e. in the boundary cells (empirical) relations for the convective coefficients are built in. WP3.2.3 Validation of the numerical methods with data measured in projects realised by the industrial partners

Description of work WP3.2.1 Laboratory test for the validation of the CFD-HAM model The surface transfer coefficient for mass transfer is usually unknown in building simulation models. The standard procedure is using the analogy between heat and mass transport to calculate this coefficient. However, this analogy does not always apply. A coupled CFDHAM model is developed which uses mass transport equations to calculate the mass transfer from or to the porous material. Knowledge of transfer coefficients is no longer necessary in this approach. However these new models require validation. Therefore there is a need for an experimental setup which can be used to study mass surface transfer coefficients and can provide experimental data for the validation of newly developed models. Details of the test setup can be found in the previous annual report and in Van Belleghem et al. (2009). During this year the test setup has been further optimized and a test wall with test sample is installed in the climate chamber. A schematic representation of this test sample is shown in Figure 30.


31

Figure 30. Test sample.

This sample consists of a 200 mm by 200 mm by 100 mm block of calcium silicate. The material properties of this sample were measured by the KULeuven. The sample is placed in a wall of the climate chamber opposite to the air inlet (for details see the previous annual report). The test sample is sliced into 4 layers. The first layer has a thickness of 10 mm, the second is 15 mm, the third layer is 25 mm and the forth layer is 50 mm. between these layers thermocouples and RH-sensors are placed. This way, temperature and relative humidity at various depths in the material can be measured. The RH-sensors are meticulously calibrated using a chilled mirror resulting in an error on the relative humidity of 1.4% RH. The side walls of the test sample are insulated to ensure a one dimensional heat transfer. At the same time, the walls of the sample are sealed with paraffin so no moisture can pass through.

Figure 31. Changes in relative humidity inside the material at various depths when the air humidity changes from 50% (16 hours) to 70% (8 hours). Three cycles are shown here.

Figure 32. Changes in temperature inside the material when the humidity of the air changes.

Figure 31 and Figure 32 show some measurement results for the climate chamber. The temperature of the inlet air was kept constant at 25°C. The sample in the climate chamber was first preconditioned at 25°C and 50% RH by keeping the inlet conditions constant for a very long time until the changes inside the material were within the accuracy limits. Then a step change of the inlet relative humidity was imposed. First a change from 50% to 70% was imposed. This 70% was maintained for 8 hours. Then the relative humidity was lowered again to 50% and maintained at this level for 16 hours. This cycle was then repeated several times. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

32

Figure 31 shows the measured relative humidity at three depths in the test sample. The deeper in the material the less pronounced the humidity fluctuations are. At high environmental relative humidity, water vapour diffuses into the porous material where it condenses. This phase change is accompanied by a release of latent heat, which results in a temperature rise as can be seen on Figure 32. WP3.2.2 Development of a CFD-HAM-model A non-isothermal coupled CFD-HAM model has been developed and validated using forced convection benchmark experiments. The model was extended with a hysteresis model to further increase the accuracy. More details on the model and its first validation can be found in Steeman et al. 2009. Studies (Roels 2008) have shown that measurement results for material properties can differ a lot from laboratory to laboratory. These material properties serve as input data for the CFDHAM model and thus determine to a great extent the accuracy of the simulation output. To be able to estimate the impact of certain parameters and properties, a sensitivity analysis is performed. As a test case the same forced convection benchmark is used as for the validation of the model. Simulations were performed for different property values. The used values are tabulated in Table 5. Changes in density, porosity, thermal conductivity and heat capacity of 5% resulted in almost no changes in the simulation outcome. Table 5. Material properties.

property Density Porosity Thermal conductivity Heat capacity

unit kg/m³ W/mK J/kgK

standard 690 0.419 0.198 840

min 655.5 0.448 0.188 798

max 724.5 0.39 0.208 882

The effect of different sorption isotherms and vapour resistance factors is however more severe. Studies show large discrepancies in measured material data and this has its impact on the model outcome.


33

Figure 33. Sorption isotherm for gypsum board, from (Roels 2008).

Figure 34. Vapour resistance factor for gypsum board (Roels 2008).

Figure 35. Relative humidity and temperature at a depth of 12.5mm (left) and 25mm (right) for different sorption isotherms.


34

Figure 36. Relative humidity and temperature at a depth of 12.5mm (left) and 25mm (right) for different vapour resistance factors.

WP3.2.3 Validation of the numerical methods with data measured in projects realised by the industrial partners

Deliverables WP3.2.1 • A test facility was build and is now operational. • Test wall with test sample and calibrated sensors is installed. • First measurements are done. WP3.2.2 • The model is validated with small scale material tests. • Sensitivity analysis performed on the model. WP3.2.3 • No actions have been undertaken here.

Planning WP3.2.1 • An extensive measurement campaign is planned starting from August. WP3.2.2 • Further study of model sensitivity. • Validation of the model on room level using measurement from new test facility. WP3.2.3 • Will be discussed with the other partners


35

WP4 Towards an integrated approach Objectives The main objective of WP4 is the generation of a prototype software environment that will enable an integral approach of all relevant heat, air and moisture transfer processes of a building. This prototype environment will be based on externally run-time coupled distribution applications, i.e. different software packages will run in parallel and exchange simulation results at appropriate time intervals throughout the simulation period. The goal of WP4 is twofold: (1) to use the prototype for increasing our knowledge regarding the modelling and simulation aspects; (2) to use the prototype for solving real-world building related HAM-problems in order to demonstrate the practical application and benefits of this approach. The work package consists of 3 subtasks: WP4.1 The development of a prototype software environment is envisaged. ESP-r is used as starting point to develop an integrated system comprising run-time coupled distributed applications. Existing models and models developed in WP1-3 will be coupled to ESP-r, for which already some preliminary external coupling features have been developed. ESP-r itself will act as overall controller and integrator. WP4.2 The development of a coupling necessity decision procedure (CNDP). An important prerequisite for this is an investigation identifying for which practical cases and circumstances which level of integrated software is needed. In addition, guidelines for selection of the proper spatial and temporal resolutions have to be provided. WP4.3 Validation and verification. Validation and verification will be conducted to validate the developed integrated model and the coupling procedure assessment method.

Description of work Progress in WP4.1 The progress in WP4.1 is split into two parts (part A and part B shown in Figure 37) which are: (A) the external coupling between BES (ESP-r) and CFD (FLUENT); and (B) the external coupling between BES (ESP-r) and HAM (HAMFEM).

Figure 37. Schematic representation of external coupling between (A) BES and CFD; (B) BES and HAM.


36

DESCRIPTION OF THE WORK IN PART A – BES and CFD A new prototype software performing coupled simulations of Building Energy Simulation (BES) and Computational Fluid Dynamics (CFD) for the heat, air and moisture transfer in the indoor environment has been developed in the third year. A new loose coupling strategy has been proposed for the run-time coupled simulation. Figure 38 shows a schematic view of the new coupling strategy applied in the prototype. It allows calling CFD every K time steps.

Figure 38. Loose coupling strategy performed at every K time steps of BES.

The number K can be set by the user and can vary from 1 to n (n is the total number of time steps in the simulation). For situations in which the boundary conditions do not change rapidly with time, it might not be necessary to call CFD at each BES time-step. It is useful in cases where the user might prefer to call CFD at a different rhythm than every time step in BES, in order to avoid repetitive CFD simulations in case of similar boundary conditions. In Figure 38, Ts and xs are surface temperatures and surface mass fractions respectively provided by BES as boundary conditions for CFD calculation. The variables hc and hm are the heat and mass transfer coefficient calculated by CFD which are sent back to BES for the next time step. Since there was no HAM model in ESP-r to provide surface mass fraction xs, the Effective Moisture Penetration Depth (EMPD) model shown in Figure 39 (left picture) was implemented in ESP-r as a simplified HAM model. The right side of Figure 39 illustrates the EMPD integration into ESP-r. The implementation was tested by contrasting different relative humidity calculations with different penetration depths for the interior surface of a single zone model as shown in Figure 40Figure 40. As can be seen from this figure, the larger the penetration depth, the more the relative humidity fluctuations of the air node are damped.


37

Relative humidity (%)

Figure 39. Left: EMPD flowchart; Right: integration of EMPD into ESP-r.

60 50 40 30 20 10 0 1

2 d = 0 mm

3

4 Days

d = 2 mm

5 d = 5 mm

6

7

d = 10 mm

Figure 40. Air node relative humidity.

A case study using the newly develop BES-CFD prototype was performed for the BESTEST case 600 (Judkoff and Neymark 1995). The model in ESP-r (a) and FLUENT (b) is shown in Figure 41 and it was run for the climate file of Brussels. A BES stand-alone simulation for an entire year shows that the indoor relative humidity reaches a maximum on 27th of June. Therefore, this period was chosen to be simulated using the prototype. Typical output of the prototype is shown in Figure 42. These results correspond to 11:00 o’clock when the air node relative humidity reaches to its maximum value in the room.


38

North

a

b

Figure 41. (a) BESTEST geometry in ESP-r graphic interface; (b) Corresponding 3D computational grid in FLUENT.

Figure 42. (a) Contours of velocity close to the west wall; (b) Contours of velocity close to the surface of the floor; (c) Humidity ratio close to the west wall.

Figure 43 compares the variation of the relative humidity of the air node using ESP-r and using the prototype. As can be seen, the relative humidity calculated by the prototype before 6 h and after 12 h is less than the predicted values by ESP-r stand-alone. Between 6 h and 12 h, the relative humidity predicted by the prototype is higher than that of ESP-r. The maximum difference between these two curves occurs around 10 o’clock and it is equal to 6.5 (%). Further study on mould growth, surface discretization and the enhancement of the prototype is ongoing.


39

Relative humidity (%)

90 80 70 60 50 40 30 20 0

4

8

12

16

20

24

Hours ESP-r

Prototype

Figure 43. Predicted relative humidity of the air node.

DESCRIPTION OF THE WORK IN PART B A new prototype software performing the coupled simulation of Building Energy Simulation (BES) and Heat, Air and Moisture (HAM) building component simulation has been developed. The details of this prototype are described in Cóstola et al. (2009), which received the student Best Paper Award at the Building Simulation Conference 2009. The main results are: (i) the definition of the coupling variables (Figure 44), (ii) the new approach used to export flux values for surface nodes from BES as a function of the surface state, which combines several phenomena (Figure 45) in a simple linear equation, (iii) the verification protocol developed to test the implementation, (iv) the use of sockets as the communication protocol, enabling faster development and verification of the code.

Figure 44. Coupling variables in BES-HAM coupling.

Figure 45. Schematic representation of some parameters used in the flux equation.


40

Progress in WP4.2 The use of CNDP is strongly dependent on the knowledge about the uncertainty in different modelling levels. The work in WP4.2 was focused on the assessment of modelling uncertainties for two variables in the external domain: convective heat transfer coefficient (CTHCEXT) and wind pressure coefficients (CP). An extensive review of empirical correlations for CHTCEXT was produced and the comparison of results shows large discrepancies between them (Figure 46). CFD simulations generated in WP1 can now be evaluated in comparison with this review.

Figure 46. Prediction of CHTCEXT by different empirical correlation for the leeward façade.

The uncertainty in Cp was addressed in two studies, the first one dealing with surfaceaveraged Cp (Costola et al. submitted), and the second one comparing an extensive database of wind tunnel results with two empirical models, “AIVC” and “Swami and Chandra” (Figure 47).

Swami and Chandra model

AIVC

Figure 47. Errors found in the predictions of Cp by “AIVC model” and “Swami and Chandra model” when compared with an extensive database of wind tunnel results.


41

Progress in WP4.3 The work developed in WP4.3 was focused on two activities: validation of the heat transfer calculation in the coupled BES-CFD simulation (Mirsadeghi et al. 2008); and verification of the BES-HAM prototype software (Costola et al. submitted). These two activities were successfully performed.

Deliverables •

•

Software development o New BES-CFD prototype for heat, air and moisture transfer for the indoor environment. o BES-HAM development for the whole building. Presentations o Monthly public PhD presentations are organised at the home university (TU Eindhoven) to provide information concerning the WP4 activities to the academic and industrial community. o Presentations on the Building Physics PhD Symposium at Eindhoven University of Technology, 2009. o Presentation at the International Building Physics Conference, Istanbul, 2009. o Presentations at the Building Simulation Conference, Glasgow, 2009. o Presentation at the Building Physics Symposium, Leuven, 2008.

Planning •

•

Software development o Validation of BES-CFD and BES-HAM prototypes. o Towards the global coupling (BES-CFD-HAM coupling): coupling of developed BES-CFD and BES-HAM prototypes . Journal papers o CNDP concept and its application. o Comparison of models and reference data. o Validation of BES-CFD coupling by model intercomparison. o Validation of BES-HAM coupling by model intercomparison. o Coupling BES and HAM programs.


42

WP5.1 Strategic and integrated planning of research activities Objectives The main objective of this subtask is the strategic and integrated planning of research activities. Within the scope of the Intelligence Network, it is foreseen to set up a committee which will have as duties: (1) to identify priority themes for basic research, applied research and dissemination activities; (2) to set up strategic planning meetings with representatives of leading Flemish industries and/or industrial associations to identify the priorities for future research; (3) to evaluate the progress and outcome of research projects and to plan the required dissemination strategies; (4) to set up a electronic project centre for use by the network members and related organisations.

Description of work Structured collaboration During the first year, there were several formal and informal discussions about the possibilities for a structured collaboration between the present partners and on longer terms with other partners. On the short and medium term, it was agreed to start up a more structured collaboration without a specific legal structure (e.g. legal status of non-profit association) in order to promote common activities. If practice proves that there is a need for, one might consider in a later phase a more formal collaboration. One of the challenges for a structured collaboration is the achievement of an intelligent balance between collaboration and competition. In certain cases, potential customers have the choice between one of the network partners without the need to involve them all. Moreover, some studies have a confidential nature. The following collaborations have started up: • Assessment of innovative systems in the EPB context : active collaboration between BBRI, UGent en K.U.Leuven This collaboration started up in 2007 and is continuing. The formal framework for the assessment of such systems is now done within the framework of the BUtgb (Belgian Union for technical approval in construction). An active widening of the assessment team with Walloon partners is planned. • Project on thermal bridges (already started before start of the SBO project): active collaboration between Sint Lucas, UGent, K.U.Leuven, Physibel and BBRI. This collaboration has continued during the 3rd year. In September 2008, a first project involving BBRI, UGent, KUL, Sint Lucas, UCL and ULG has been started with support from the 3 regions. As a follow-up, there is in 2009 a new project with K.U.Leuven as leader. Brainstorming on projects and programs The project “post-insulation of existing walls” shows a large potential with respect to the insulation of existing cavity walls, whereby there are still some pending issues. In the meanwhile, external insulation of existing walls has become a mature technology with a whole range of solutions. Specific points of attention still remain. The other alternative, i.e. internal insulation, is from a buildings physics point of view not so evident but, in practice, quite often the only feasible solution.


43

The federal as well as the regional governments are strongly interested in improving the insulation of existing walls. In order to initiate a broad discussion on this issue, the SBO workshop on September 10th aims to report on the present status and the pending questions. It is expected that this will result in a series of actions with as purpose to come to pragmatic approaches for a wide-scale applications. Communication and dissemination In order to facilitate communication between the partners and with the external building community, a completely new website has been set up by BBRI. (www.infoham.be). Monitoring of website use is done using Urchin. Training as a mean of disseminating the results of the structured collaboration Workshops • 2007: CFD is becoming increasingly operational for use in daily practice. On September 20th 2007; and in order to show the potential of CFD, a workshop was organised in the framework of the SBO project. • 2008 : On September 4th 2008 a 2nd workshop was organised around the topic of ‘heat, air and moisture management in historic buildings’. • 2009 : On September 10th 2009, a 3rd workshop will be organised on the topic of insulation of existing walls. The interest is very wide, as is illustrated by the fact that there were on August 25th already some 120 requests for participation. Post-graduate course An advanced course on heat, air and moisture transfer in buildings is under preparation. As indicated in the proposal, it will be a higher course ‘Heat, air and moisture transfer: an integrated approach’. This course will be organised in collaboration with several organisations, including the Technical Institute of the KVIV, the Dutch-Flemish Buildings Physics Association, IBPSA (International Buildings Performance Simulation Association, ATIC, TVVL, …. The detailed planning has well progressed and a meeting was organised by K.U.Leuven.

Deliverables • • •

A TETRA-project ‘Post-insulation’ was obtained and several partners are involved in the structure for assessment of innovative systems in the EPB context. There is structural collaboration envisaged around the topic of insulation of existing walls. For 2009, the workshop on insulation of existing walls is another deliverable of this WP.

Planning • • •

Further attention will be paid to inscribe the collaboration between all partners in future research projects and about the structuring the collaboration practically in order to deal with demands of industry. The website www.infoham.be will be further expanded in the course of 2009-2010. The higher course will be held in 2010.


44

WP5.2 Strategic implementation of testing and simulation facilities Objectives The main objective of this subtask is the strategic implementation of testing and simulation facilities. The consortium has already a wide range of testing and simulation facilities.

Description of work In a first phase all partners have been demanded to make up a list of the testing facilities of which they dispose. The collection of information on software tools has started up. It is the intention to have a specific filter on the software tools database as developed by DOE (http://www.eere.energy.gov/buildings/tools_directory/subjects_sub.cfm ). The role of high quality laboratory infrastructure is of key importance for progress in basic research. The listing of the testing and simulation facilities is a useful tool for each partner to define his needs for missing infrastructure and to come to a priority list for investments in missing infrastructure. Based on the list of measurement utilities and the need for measurement utilities, the missing links that are useful for all partners can be defined.

Deliverables •

There is general information available on the website www.infoham.be.

Planning •

Will be discussed with the other partners


45

References BBRI (1999), Insulation, ventilation and heating in newly built dwellings: results of a survey, BBRI, Brussels, Belgium (in Dutch). CMHC (2001), Air leakage characteristics, test methods and specifications for large buildings, CMHC Research Highlights 01-123, www.cmhc-shcl.gc.ca. Cóstola D., Blocken B., Hensen J.L.M. (2009), External coupling between BES and HAM programs for whole-building simulation, Proceedings of the 11th IBPSA Conference, 27- 30 July, Glasgow: IBPSA. Cóstola D., Blocken B., Ohba M., Hensen J.L.M., Uncertainty in airflow rate calculations due to the use of surface-averaged pressure coefficients, submitted to Energy and Buildings. Goethals K., Janssens A. (2008), Sensitivity analysis of thermal performance to convective heat transfer at internal building surfaces, Proceedings of the Building Physics Symposium, Leuven, Belgium, pp. 147-150. Goethals K., Laverge J., Janssens A. (2009a), Sensitivity analysis of thermal predictions to the modeling of direct solar radiation entering a zone, Proceedings of RoomVent 2009, Busan, Korea, pp. 1179-1186. Goethals K., Janssens A. (2009b), Sensitivity analysis of CHT to diffuser modelling in CFD, Proceedings of Building Simulation 2009, Glasgow, Scotland, pp. 450-457. Judkoff R., Neymark J. (1995), International Energy Agency Building Energy Simulation Test (BESTEST) and diagnostic method, Report NREL/TP-472-6231, Golden: NREL. Mirsadeghi M., Blocken B., Hensen J.L.M. (2008), Validation of external BES-CFD coupling by inter-model comparison, Proceedings of the 29th AIVC Conference, 14-16 October, Kyoto: AIVC, 2008. Parmentier B. (2003), Les effets du vent sur les toitures inclinées – La recherche au CSTC et ses enseignements, CSTC-Magazine, Bruxelles, pp 3 -17. Roels S. (2008), IEA Annex 41 - Whole Building Heat, Air , Moisture response. Subtask 2: Experimental Analysis of Moisture Buffering, Technical report, International Energy Agency. Steeman H. J., Van Belleghem M., Janssens A., De Paepe M. (2009), Coupled simulation of heat and moisture transport in air and porous materials for the assessment of moisture related damage, Building and Environment 44 (10), 2176-2184. Van Belleghem M., Steeman H.-J., Janssens A., De Paepe M. (2009), Heat and moisture transfer between air and porous materials: a test setup for benchmark experiments, 4th International Building Physics Conference, Istanbul.


46

1.2 Bijsturingen in het project Onderzoeksinhoud Er zijn tijdens het derde projectjaar geen bijsturingen van het project nodig gebleken wat betreft onderzoeksinhoud.

Onderzoeksbegeleiding Er zijn tijdens het derde projectjaar geen bijsturingen van het project nodig gebleken wat betreft onderzoeksbegeleiding.

1.3 Beheer van het project Het beheer van het project bestaat uit verschillende componenten. Vooreerst is er het algemene projectbeheer dat de strategische en structurele aspecten van het project behelst. Het wetenschappelijke beheer betreft de organisatie, opvolging en evaluatie van het onderzoekswerk in de deelnemende onderzoeksgroepen en hun onderlinge communicatie. Tot slot moet ook de interactie met de gebruikersgroep beheerd worden. De ontwikkelde website is voor deze componenten een belangrijk instrument.

Algemeen projectbeheer Bij het project zijn 9 partners betrokken, waarvan 3 industriële partners: • Katholieke Universiteit Leuven, Laboratorium Bouwfysica: Staf Roels (KUL) • Universiteit Gent, vakgroep Mechanica van Stroming, Warmte en Verbranding: Erik Dick (UG-FHC), Michel De Paepe ((UG-FHC) • Universiteit Gent, vakgroep Architectuur en Stedenbouw: Arnold Janssens (UG-AS) • Technische Universiteit Eindhoven, Unit Building Physics & Systems: Jan Hensen (TU/e) • Wetenschappelijk en Technisch Centrum voor het Bouwbedrijf, departement Geotechniek en Structuren: Benoit Parmentier (WTCB-GS) • Wetenschappelijk en Technisch Centrum voor het Bouwbedrijf, departement Bouwfysica en Uitrustingen: Peter Wouters (WTCB-BU) • Daidalos Bouwfysisch Ingenieursbureau: Filip Descamps (DAI) • Physibel: Piet Houthuys (PHYS) • Ingenieursbureau Stockman: Piet Delagaye (STO) Tussen deze negen partners werd bij het begin van het eerste projectjaar een consortium overeenkomst afgesloten, welke de contractuele aangelegenheden van de samenwerking bevestigt. Deze betreffen de achtergrondkennis van de partners, de reeds bestaande software ontwikkeld door de partners en de bescherming van de projectresultaten. Het Project Coordination Commitee (PCC) wordt gevormd door Peter Wouters(WTCB-BU), Benoit Parmentier (WTCB-GS), Piet Delagaye (STO), Jan Hensen (TU/e), Michel De Paepe (UG-FHC), Arnold Janssens (UG-AS), Filip Descamps (DAI), Piet Houthuys (PHYS), Hugo Hens (KUL) en Staf Roels (KUL), dat instaat voor het algemene beheer van het project.

Wetenschappelijk projectbeheer


47

Binnen iedere deelnemende onderzoeksgroep neemt de werkpakketleider het dagelijkse projectbeheer op zich. Hij evalueert de wetenschappelijke vooruitgang van de onderzoekers van de onderzoeksgroep en rapporteert halfjaarlijks dienaangaande aan het PCC. Het wetenschappelijk beheer beoogt verder een goede samenwerking en uitwisseling tussen de verschillende onderzoekers. De onderzoeksresultaten en -plannen worden steeds gepresenteerd op de halfjaarlijkse vergaderingen met de stuurgroep. Daarenboven zijn er gedurende het afgelopen jaar verschillende contactenmomenten geweest tussen de onderzoekers.

Gebruikersgroep projectbeheer Zie 2.2 Overzicht van de uitgevoerde valorisatieacties, oprichting en vergaderingen gebruikersgroep.

1.4 Haalbaarheid van het project Het project verloopt goed, zowel voor onderzoek als valorisatie. Ten gevolgen van enkele personeelswissels en laattijdige start van enkele doctoraatsstudenten in de eerste twee projectjaren is er in enkele deelpakketten wat achterstand opgelopen. Daarom werd er een projectverlenging aangevraagd van 6 maanden. Er zijn immers nog voldoende financiele middelen voorhanden om dit te bekostigen. Indien deze goedgekeurd wordt, worden er geen problemen verwacht inzake de haalbaarheid van het project. De overige deelpakketen zijn op schema of liggen voor op schema. Alle zeven de onderzoeksfuncties zijn ingevuld op dit moment. De haalbaarheid van het project wordt niet in vraag gesteld. Zie 2.2 Overzicht van de uitgevoerde valoriatieacties voor een overzicht van de reeds ondernomen valorisatiereacties

1.5 Te beschermen resultaten De uit dit projectjaar resulterende software wordt nog niet publiekelijk verspreid wat bescherming nog niet noodzakelijk maakt.


48

2 Utilisatieverslag 2.1 Valorisatiepotentieel: geactualiseerde visie Toepassingsgebieden Dit project heeft als doel het verenigen van verschillende onderzoeksdomeinen om zo te komen tot een geïntegreerde benadering van warmte-, lucht-, en massatransport in gebouwen. Deze benadering dient in eerste instantie om kennis te verzamelen omtrent het koppelen van verschillende numerieke modellen in een geïntegreerd model. Deze integrale benadering moet leiden tot een optimalisatie van gebouwen, zowel wat betreft economische besparingen als duurzame ontwikkeling. Dit maakt dat het project verscheidene toepassingsgebieden heeft: • Bij het ontwerp en de constructie van nieuwe hoogtechnologische gebouwen proberen de ontwerpers de gebouwrespons inzake warmte-, lucht- en vochtgedrag te voorspellen en te regelen. Hierbij kan de door het project ontwikkelde kennis bijdragen tot een inzicht in de interactie tussen onder andere HVAC systemen en de gebouwschil. Dit kan leiden tot de optimalisatie van HVAC controlesystemen. • Om kleine gebouwen duurzaam en energiezuinig te maken, worden er verschillende innovatieve systemen ontwikkeld, zoals gevels met stalen of houten frames waartussen hygroscopisch bufferende materialen worden geplaatst met dampopen binnen- en buitenbekleding. Een geïntegreerde aanpak laat een gedetailleerde analyse van de duurzaamheid van deze systemen toe. • De geïntegreerde aanpak kan ook van nut zijn bij de renovatie en restauratie van het Vlaams cultureel erfgoed. Aangezien er hierbij meestal ingrijpende veranderingen worden doorgevoerd, is een goede evaluatie van de respons van het gebouw op deze nieuwe situatie van belang. Daarnaast kan de methodologie ook leiden tot een geoptimaliseerde strategie voor de bescherming van cultureel erfgoed (musea, monumentale orgels, schilderijen, …). • De geïntegreerde aanpak kan meer inzicht bieden in de invloed van de buitencondities op de luchtstroming binnen voor de analyse van natuurlijke ventilatiestrategieën. Ook voor koeling d.m.v. nachtventilatie kan dit nuttig zijn. Uiteraard kan dit project ook van nut zijn in andere toepassingsgebieden, waarvan er enkele aangehaald worden verderop in de tekst.

Valorisatie- en absorptiepotentieel Dit project heeft als doel de ontwikkeling van een geïntegreerd model wat moet toelaten om het hygrothermisch gedrag van gebouwen gedetailleerd te evalueren. Er zullen verscheidene programma’s gebruikt worden op verschillende niveaus en, afhankelijk van de toepassing, al dan niet gekoppeld. De belangrijkste zijn CFD, gebouwenergiesimulatieprogramma’s en gekoppelde warmte-, lucht- en vochttransportmodellen. Op lange termijn wordt de commerciele ontwikkeling van een geïntegreerd model beoogd. Omwille van de complexiteit van de programma’s is het wat ambitieus om deze ontwikkeling op korte termijn te zien. Deze ontwikkelingen zullen later dus vooral tot nut zijn voor studiebureaus en software ontwikkelaars. Op korte termijn is echter de verspreiding en toegankelijkheid van de opgebouwde kennis naar de bouwsector toe van belang. Dit laatste komt het utilisatiepotentieel zeker ten goede aangezien elke begunstigde de verworven kennis kan aanwenden om in zijn werkgebied vooruitgang te boeken. De strategie die hiervoor ontwikkeld werd, wordt in de volgende paragraaf besproken. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

49

Valorisatieplan en acties voor de verspreiding van kennis Opdat de bouwsector de ontwikkelde kennis kan aanwenden is het belangrijk dat deze kennis door de projectpartners op een duidelijke wijze wordt overdragen. Dit is één van de hoofddoelstellingen van WP5. Om het valorisatie en absorptiepotentieel van het project te vergroten werd er een gebruikersgroep opgericht. De leden van deze gebruikersgroep hebben niet alleen als functie om de kennis over te dragen. Zij worden ook verwacht om tijdens het project feedback te geven over de resultaten. De gebruikersgroep werd samengesteld uit een zo breed mogelijk publiek uit verschillende subgroepen in de bouwnijverheid: 1) de sector van productontwikkeling en de producenten van bouwmaterialen; 2) architecten en aannemers samen met professionele klanten; 3) ingenieursbureaus en gebouwbeheer (building management offices); 4) de wetenschappelijke onderzoekswereld; 5) gebruikers die zich bezighouden met duurzame ontwikkeling in de bouwnijverheid. Deze opdeling in subgroepen werd gemaakt opdat de overdracht van kennis zou kunnen gerealiseerd worden op een gepaste wijze voor elke subgroep. Door middel van aangepaste sessies voor één of verschillende subgroepen kan de verworven kennis toegankelijk gemaakt worden. Voorbeelden hiervan zijn de CFD workshop (Het gebruik van CFD bij het ontwerp van gebouwen en installaties) en de workshop over historische gebouwen (Warmte-, lucht- en vochtproblematiek bij historische gebouwen) aansluitend bij de tweede (september 2007) en derde plenaire (september 2008) vergadering van de gebruikersgroep respectievelijk. Waar de eerste workshop vooral bedoeld was om subgroepen 1, 3 en 4 aan te spreken, was de tweede workshop eerder toegankelijk voor praktisch alle subgroepen. Ook de geplande workshop (Na-isolatie van muren – Wat zijn de mogelijkheden?) aansluitend bij de vierde plenaire vergadering (september 2009) van de gebruikersgroep heeft als doel kennis over te dragen aan de gebruikersgroep en is toegankelijk voor praktisch alle subgroepen. In het verdere verloop van het project zullen er nog zulke sessies gehouden worden die toegankelijk zijn voor meerdere subgroepen. Een ander initiatief wat bijdraagt tot de verspreiding van de kennis van de partners is de oprichting van InfoHAM (www.infoham.be), wat dient als een informatie netwerk omtrent onderzoek over warmte-, lucht- en massatransport. Daarenboven zal InfoHAM ook cursussen en lezingen organiseren, zoals reeds vermeld werd in de vorige jaarverslagen onder WP5. De goede samenwerking tussen de verschillende onderzoeksinstellingen is ook belangrijk aangezien deze zorgt voor een uitwisseling en uitbreiding van kennis en expertise in de verschillende vakgebieden. Hierbij is tevens de bijdrage van de industriële partners van groot belang.

Verdere toepassingsgebieden Aangezien dit project een integratiemethodologie zal aanreiken, kan dit in vele andere onderzoeksdomeinen ook toepassingen hebben welke evenwel niet beperkt zijn tot de bouwsector. Hieronder worden enkele mogelijke toepassingsgebieden aangehaald. Een uitgebreide beschrijving ervan kan gevonden worden in de projectaanvraag. • Optimisatie van productieprocessen voor materialen • Slagregen als een randvoorwaarde voor onderzoek in bouwfysica en aardwetenschappen • Schadeanalyse van onderdelen van het cultureel erfgoed in historische gebouwen • Optimalisatie van 3D (thermische) simulatieprogramma’s • Optimalisatie van binnenomgevingen van auto’s, vliegtuigen en treinen IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

50

• •

Computer gestuurd ontwerp van bio-thermische processen van landbouwproducten Optimalisatie van koeling van elektronische componenten en temperatuurmanagement van PCB’s door gebruik te maken van de VLES techniek


51

2.2 Overzicht van de uitgevoerde valorisatieacties Dit onderdeel geeft aan welke valorisatieacties er ondernomen zijn tijdens het derde projectjaar.

Oprichting en vergaderingen gebruikersgroep Er werd een gebruikersgroep opgericht bij de aanvraag van het project dewelke momenteel 29 leden telt: • CIR • CIR-Styfabel • Febe • IsoproC • Renson • Reynaers Aluminium • Verozo • Artex/Matexi • Brussels Office for Architecture • NAV, de Vlaamse Architectenorganisatie • Vlaamse Huisvestingsmaatschappij • Zonnige Kempen • 3E • Bureau Bouwtechniek • Cenergie bvba • Decysis bvba • Grontmij Atenco nv • Ingenium • REUS • Studiebureau R. Boydens bvba • VK Engineering • K.U.Leuven, Labo Agrarische Bouwkunde • UGent, Onderzoeksgroep Biosysteemtechniek • VITO • Centrum Duurzaam Bouwen • Dialoog vzw • Kamp C • Passiefhuis-Platform vzw • Technologisch Instituut vzw Tijdens de startvergadering (8 september 2006) werd hen het project voorgesteld: doelstellingen, strategie en onderzoeksplanning. De daaropvolgende vergaderingen voor de gebruikersgroep waren op 20 september 2007 en 4 september 2008. De komende vergadering met de gebruikersgroep is gepland op 10 september 2009. Na elke vergadering is er ruimte voor feedback voorzien. Na elke vergadering krijgen de leden van de gebruikerscommissie ook een verslag van de vergadering toegestuurd.


52

Publicaties in tijdschriften en presentatie op conferenties Er zijn reeds verscheidene papers ingediend en aanvaard voor publicatie in een internationaal tijdschrift. De projectresultaten zijn ook reeds voorgesteld op meerdere internationale conferenties, waarvan de desbetreffende papers zijn opgenomen in de proceedings: Journal papers ingediend Defraeye T., Blocken B., Carmeliet J. (2009), Convective heat transfer coefficients for exterior building surfaces: Existing correlations and CFD modeling, Energy and Buildings, Submitted. Köse D., Dick E., Prediction of the pressure distribution on a cubical building with implicit LES, Journal of Wind Engineering and Industrial Aerodynamics. Cóstola D., Blocken B., Ohba M., Hensen J.L.M., Uncertainty in airflow rate calculations due to the use of surface-averaged pressure coefficients, submitted to Energy and Buildings. geaccepteerd Defraeye T., Blocken B., Carmeliet J., CFD analysis of convective heat transfer at the surfaces of a cube immersed in a turbulent boundary, International Journal of Heat and Mass Transfer, Accepted for publication in International Journal of Heat and Mass Transfer. Abuku M., Blocken B., Roels S., Moisture response of building facades to winddriven rain: field measurements compared with numerical simulations, Accepted for publication in Journal of Wind Engineering and Industrial Aerodynamics. Vereecken E., Roels S., Janssen H., Inverse characterisation of the hygric inertia of building enclosures, Accepted for publication in Journal of Building Physics. gepubliceerd Blocken B., Defraeye T., Derome D., Carmeliet J. (2009), High-resolution CFD simulations for forced convective heat transfer coefficients at the facade of a low-rise building, Building and Environment 44 (12), 2396-2412. Abuku M., Janssen H., Poesen J., Roels S. (2009), Impact, absorption and evaporation of raindrops on building facades, Building and Environment 44 (1), 113-124. Abuku M., Janssen H., Roels S. (2009), Impact of Wind-Driven Rain on historical brick wall buildings in a moderate cold and humid climate: numerical analyses of mould growth risk, indoor climate and energy consumption, Energy and buildings 41 (1), 101-110. Janssen H., Roels S. (2009), Qualitative and quantitative assessment of interior moisture buffering by enclosures, Energy and buildings 41, 382-394. Abuku M., Blocken B., Nore K., Thue JV., Carmeliet J., Roels S. (2009), On the validity of numerical wind-driven rain simulation on a rectangular low-rise building under various oblique winds, Building and Environment 44 (3), 621-632. IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

53

Steeman H. J., Janssens A., Carmeliet J., De Paepe M. (2009), Modelling indoor air and hygrothermal wall interaction in building simulation: Comparison between CFD and a well-mixed zonal model, Building and Environment 44 (3), 572-583. Steeman H. J., Janssens A., De Paepe M. (2009), On the applicability of the heat and mass transfer analogy in indoor air flows, International Journal of Heat and Mass Transfer 52 (5-6), 1431-1442. Steeman H. J., Van Belleghem M., Janssens A., De Paepe M. (2009), Coupled simulation of heat and moisture transport in air and porous materials for the assessment of moisture related damage, Building and Environment 44 (10), 21762184. Costola D., Blocken B., Hensen J.L.M. (2009), Overview of pressure coefficient data in building energy simulation and airflow network programs, Building and Environment 44 (10), 2027-2036.

Proceedings gepubliceerd Defraeye T., Blocken B., Carmeliet J. (2009), CFD analysis of the convective heat transfer coefficient at the facades of a cubic building, Proceedings of the 4th International Building Physics Conference, Istanbul, Turkey. Defraeye T., Blocken B., Carmeliet J. (2009), Computational modelling of convective heat and moisture transfer at exterior building surfaces, Proceedings of the 7th International Conference on Urban Climate, Yokohama, Japan. Defraeye T., Blocken B., Carmeliet J. (2009), CFD analysis of convective heat transfer coefficients on the exterior surfaces of a cubic building, Proceedings of the 7th International Conference on Urban Climate, Yokohama, Japan. Goethals K., Laverge J., Janssens A. (2009), Sensitivity analysis of thermal predictions to the modeling of direct solar radiation entering a zone, Proceedings of RoomVent 2009, Busan, Korea, pp. 1179-1186. Janssen H., Roels S. (2009), Qualitative and quantitative assessment of interior moisture buffering, Proceedings of Building Simulation 2009, University of Strathclyde, Glasgow, UK. Vereecken E., Janssen H., Roels S. (2009), In situ determination of the moisture buffer potential of room enclosures, Proceedings of Building Simulation 2009, University of Strathclyde, Glasgow, UK. Abuku M., Roels S., Janssen H., Poesen J. (2009), Towards a reliable prediction of moisture response of walls to wind-driven rain, Proceedings of the 4th International Building Physics Conference (4thIBPC), Istanbul, Turkey.


54

Abuku M., Janssen H., Roels S. (2009), An onset to whole building simulation: winddriven rain impact on mould growth risk, indoor climate and energy consumption, Proceedings of the Building Simulation 2009 (BS2009), Glasgow, UK. Abuku M., Blocken B., Poesen J., Roels S. (2009), Spreading, splashing and bouncing of wind-driven raindrops on building facades, Proceedings of the 11th Americas Conference on Wind Engineering (11th ACWE), San Juan, Puerto Rico. Abuku M., Blocken B., Roels S. (2009), Field measurement and numerical analysis of wind-driven rain absorption and evaporation on building facades, Proceedings of the 5th European & African Conference on Wind Engineering, Florence, Italy. Van Belleghem M., Steeman H.-J., Janssens A., De Paepe M. (2008), Local heat and moisture transfer between indoor air and building materials: a benchmark experiment, Proceedings of the Building Physics Symposium BPS 2008, Leuven, Belgium. Steeman H.-J., Janssens A., De Paepe M. (2008), On the different definitions of mass transfer coefficients, Proceeding of the Building Physics Symposium BPS 2008, Leuven, Belgium. Steeman H.-J., Janssens A., De Paepe M. (2008), A coupled CFD-material model for the prediction of heat and moisture fluxes to hygroscopic porous materials, Proceedings of the 19th International Symposium on Transport Phenomena, ISTP-19, Reykjavik, Iceland. Van Belleghem M., Steeman H.-J., Janssens A., De Paepe M. (2009), Heat and moisture transfer between air and porous materials: a test setup for benchmark experiments, Energy efficiency and new approaches, Proceedings of the Fourth International Building Physics Conference, Istanbul, Turkey. Van Belleghem M., Steeman H.-J., Huisseune H., T’Joen C., Janssens A., De Paepe M. (2009), Heat and mass transfer between air and porous materials: a benchmark experiment, Proceedings of the 7th World Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics, Krakow, Poland. Köse D., Dick E. (2009), ILES of airflow around buildings, Proceedings 8th National Congress on Theoretical and Applied Mechanics, Brussels, Belgium, 10pp. Cóstola D., Blocken B., Hensen J.L.M. (2009), External coupling between BES and HAM programs for whole-building Simulation, Proceedings of the 11th IBPSA Conference, Glasgow. Mirsadeghi M., Blocken B., Hensen J.L.M. (2009), Application of externally-coupled BES-CFD in HAM engineering of the indoor environment, Proceedings of the 11th IBPSA Conference, Glasgow. Cóstola D., Blocken B., Hensen J.L.M. (2009), A comparison of generic pressure coefficient for indoor air flow studies, Proceedings of the 4th International Building Physics Conference, Istanbul.


55

Cóstola D., Mirsadeghi M., Blocken B., Hensen J.L.M. (2008), Towards external coupling of BES and HAM envelope programs for whole-building HAM simulation, Building Physics Symposium, Leuven. ingediend Goethals K., Janssens A. (2010), Sensitivity analysis of convective heat transfer to the diffuser type and its location using computational fluid dynamics, abstract submitted to Clima 2010, Antalya, Turkey. Desta T. Z., Roels S. (2010), Experimental and numerical analysis of heat, air and moisture transfer in a light weight building wall, Thermal Performance of Exterior Envelopes of Whole Buildings XI International Conference, Florida, USA, Abstract accepted. Andere tijdschriften (professionele journals) Dit projectjaar zijn er geen publicaties in professionele journals uitgebracht.

Interne rapporten en meetings Publicaties in internationale tijdschriften en voorstellingen op internationale conferenties worden in de loop van het project aangevuld met interne technische rapporten en software handleidingen, om de uitwisseling van kennis tussen de verschillende onderzoekers te vergemakkelijken. Deze rapporten zullen ook ter beschikking gesteld worden aan de gebruikersgroep. Dit projectjaar zijn er echter geen interne rapporten opgesteld. Daarenboven zijn er ook in het derde projectjaar twee stuurgroepvergaderingen geweest (6 februari en 27 augustus 2009) waar alle onderzoekers hun resultaten voorstelden. Daarna volgde een collectieve bespreking van de verdere onderzoeksstrategie en planning.

Cursussen, workshops, conferenties en aanverwante activiteiten De uit het onderzoeksprogramma voortvloeiende kennis en expertise worden bekendgemaakt op studiedagen, cursussen, conferenties en workshops gericht naar de belanghebbende actoren uit zowel de bouwsector als de wetenschappelijke wereld. Daarenboven wordt de verworven kennis reeds aangewend in aanverwante onderzoeksprojecten en in industriële opdrachten. Hier volgt een overzicht van deze activiteiten: Cursussen en workshops • PhD Summer Course: Heat and Mass Transport in Building and Urban Physics, (Blocken B. (2de week in cursus gecoördineerd)), Zurich, Switzerland, 29 juni-10 juli, 2009. Zomercursus waarop de basisprincipes maar ook een aantal van de laatste ontwikkelingen worden gedoceerd aan PhD-studenten, postdocs en mensen uit de praktijk. • Workshop ivm warmte- en vochtproblematiek in historische gebouwen (4 september 2008): Workshop in het kader van het SBO project. Deze workshop werd georganiseerd door de SBO projectpartners. • Maandelijkse PhD “progress” meetings aan Technische Universiteit Eindhoven: Meetings georganiseerd in de tweede helft van elke maand, waarop academische en industriële partners aanwezig zijn om informatie te bekomen over de nieuwe ontwikkelingen in WP4. De nauwe band met de industrie en praktijk waarborgt de praktische relevantie van het onderzoek (gecoördineerd door Jan Hensen). IWT SBO project 050154 – Heat, air and moisture performance engineering - A whole building approach Derde jaarlijks rapport

56

•

Cursus Energietechniek in gebouwen (IVPV-KVIV): Lezingen door A. Janssens en M. De Paepe. Post-academische opleiding waarin de gebruikte onderzoeksresultaten worden aangewend.

Conferenties en symposia • Building Physics Symposium (29-31 oktober 2008, Leuven): Symposium ter ere van Prof. H. Hens georganiseerd door het Laboratorium Bouwfysica aan de KULeuven (S. Roels). Aanverwante onderzoeksprojecten ter ondersteuning van of resulterend uit het project • Steeman H.-J. (2009), Modelling Local Hygroscopic Interaction between Airflow and Porous Materials for Building Applications, PhD Thesis, Ghent University, Ghent, Belgium • IWT specialisatiebeurs – SB-81322, Studie van vloeistoftransport en inwendige condensatie in gebouwen, (Bursaal Marnix Van Belleghem, Promotor Michel De Paepe) • EPICOOL – Voorstel tot wijziging van de energieprestatieberekeningensmethode van gebouwen met betrekking tot koeling Varia • Gebruik van de ontwikkelde modellen in industriële opdrachten door Vakgroep Mechanica van Stroming, Warmte en Verbranding (UGent): o Testen van de thermische prestatie van PCM houdend textiel, EOC Belgium, Industriepark De Bruwaan 24, 9700 Oudenaarde, België, verslag nr. 09015, Universiteit Gent. o Performance analysis of air curtains, NV. DeWeerdt, Lumbeekstraat 89, 1700 Sint-Ulriks-Kapelle, België, verslag 08031, Universiteit Gent. o Luchtdoorlatendheid test op textile, Dienst gebouwen en facilitair beheer Universiteit Gent, verslag nr. 09016, Universiteit Gent. • Samenwerking met Tokyo Polytechnic University voor de berekening van onzekerheden in modellering bij eenvoudige modellen voor winddruk coefficienten (Costola et al. 2009).

Opstellen jaarverslagen Het wetenschappelijk-technisch deel van het jaarverslag vormt een belangrijk onderdeel in de kennisoverdracht naar de gebruikersgroep betreffende de behaalde projectresultaten.

Ontwikkeling website Er werd een website ontwikkeld in het eerste projectjaar waar externen de verslagen van vergaderingen met de gebruikerscommissie kunnen vinden alsook de jaarrapporten. De site (www.infoham.be) werd in het voorbije projectjaar verder uitgebreid. Zo bevat deze site nu ook informatie over de partners, geplande activiteiten (workshops e.d.), aanverwante projecten, inventarissen van de beschikbare meetapparatuur en simulatietools van de projectpartners, etc. Deze site is zo een belangrijk instrument om de interne werking en uitwisseling van verslagen en voorstellingen te vergemakkelijken en om externe geïnteresseerden te informeren over de activiteiten in het kader van het project.


57

2.3 Bescherming projectresultaten De in dit project ontwikkelde software wordt nog niet publiekelijk verspreid wat bescherming nog niet noodzakelijk maakt. Acties ter bescherming van de projectresultaten zijn daarom ook nog niet ondernomen.


58

3 Financieel verslag 3.1 Prestatietabel De prestatietabellen voor de negen partners voor het projectjaar 2008-2009 worden bezorgd aan het IWT door K.U.Leuven LRD.


59

3.2 Prognose voor komende projectjaar De inzet van mensen voor het projectjaar 2009-2010 wordt als volgt ingeschat. Partner KUL UG-FHC UG-AS WTCB-GS WTCB-BU

TUE PHYS DAI STO

Medewerker Thijs Defraeye Tadiwos Zerihun Desta Hendrik-Jan Steeman Arnout Willockx Demir-Ali Köse Kim Goethals Benoit Parmentier Peter Wouters Gilles Flamant Xavier Loncour Didier L’heureux Philippe Voordecker Brieuc Meurisse Mohammad Mirsadeghi Daniel Costola Piet Houthuys Piet Standaert Filip Descamps Piet Delagaye

barema bursaal wet.mw. post-doc. wet. mw. bursaal bursaal ir. tech. ir. ir. ir. tech tech. tech bursaal bursaal dr.ir. dr.ir. dr.ir.-arch. ir.

maanden 12 12 1 4 12 12 4 1 1 5.9 2 3 4 1.2 12 12 0.25 0.25 ntb ntb

periode 01/09/09-31/08/10 01/09/09-31/08/10 01/09/09-31/08/10 01/09/09-31/08/10

01/09/08-31/08/09 01/09/08-31/08/09

De inzet van middelen wordt niet ingeschat, er zijn geen grote onderaannemingen of aankopen gepland.


60

3.3 Financiële verantwoording De kostenstaten voor de negen partners voor het tweede projectjaar worden bezorgd aan het IWT door K.U.Leuven LRD. Hierbij dienen enkele opmerkingen gemaakt te worden: •

•

Voor taken 3.2.1 en 3.2.2 was bij het begin van het derde projectjaar een achterstand opgelopen doordat het niet mogelijk was bij aanvang van het project de voorziene doctoraatsbursaal aan te werven. In het derde projectjaar is de achterstand weggewerkt door gedeeltelijke inzet van een twee doctoraatsstudenten waarvan het loon niet betaald is op het project en door gedeeltelijke inzet van twee postdoctorale onderzoekers waarvan het loon wel op het project is betaald. Er is zelfs voorsprong bereikt op de planning. Wegens problemen inzake personeel (een vervanger van de persoon van het WTCB die in het begin van het project in dit werkpakket betrokken was is nog niet gevonden), zijn de geplande manmaanden voor het derde jaar enkel gedeeltelijk gebruikt. De testen in de Paslink testcellen zullen tijdens het vierde jaar verder uitgevoerd worden. Er wordt voorgesteld om deze manmaanden naar het vierde jaar te verplaatsen. Er wordt ook aan IWT voorgesteld om 2 manmaanden (voor het WTCB) te verplaatsen naar UGent (met overdracht van budget) voor het vierde jaar voor de analyse van metingen. WP3.1 Ingenieur Technieker

Derde projectjaar Gepland Gerealiseerd 11 1.14 11.5 3.33

Vierde projectjaar Voorzien Voorgesteld 1 10.9 0 8.2


61

SBO project IWT Derde jaarlijks rapport

Recommend Documents