Conference Agenda

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Please note that all times are shown in the time zone of the conference. The current conference time is: 7th July 2022, 16:44:57 CEST

Session Overview
Session T1.4: Improving indoor environmental quality
Thursday, 02/Sept/2021:
8:30 - 10:00

Session Chair: Dariusz Heim, Lodz University of Technology
Session Chair: Hayder Alsaad, Bauhaus-University Weimar
Location: Cityhall (Belfry) - Room 4

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8:30 - 8:48

Development of a 3D and high resolution dynamic thermal model of a room with sun patch evolution for thermal comfort applications

Teddy Gresse1, Lucie Merlier2, Jean-Jacques Roux1, Frédéric Kuznik1

1Univ Lyon, INSA Lyon, CNRS, CETHIL, UMR5008, 69621 Villeurbanne, France; 2Univ Lyon, UCBL, INSA Lyon, CNRS, CETHIL, UMR5008, 69622 Villeurbanne, France

Aim and Approach

(max 200 words)

Rapidly varying environmental phenomena, such as solar radiation or airflows can significantly affect thermal comfort. Hence, this contribution presents the development and validation of an efficient dynamic thermal model designed to simulate a room for thermal comfort applications, using a 3D and high-resolution description of heat conduction in the envelope and surface balances. In particular, the model can handle short-time steps and calculates the sun patch, which corresponds to the projection of solar radiation through a window onto interior walls.

The model is validated using detailed experimental data of a low energy building called BestLab [1]. Surface temperature and indoor air temperature are especially compared, and the discrepancies are quantified.

Scientific Innovation and Relevance

(max 200 words)

Building thermal models generally aim to predict the energy consumption of buildings. Thus, they consider thermal loads over a long period such as a year, and neglect or simplify some features of thermal transfers. Conduction in the building envelope is typically considered 1D, short-wave radiation is projected on the floor and typical hourly weather data are used.

Yet, buildings and indoor environmental conditions are exposed to rapid environmental variations. As a response, surface temperature distribution, indoor airflows and room air temperature may substantially but locally vary, which can affect the thermal comfort of inhabitants [2] [3]. Thus, relevantly addressing thermal comfort requires higher resolution simulations able to manage locally rapid environmental variations. In particular, the use of a 3D model that includes the calculation of the sun patch and relevant convective effects can significantly improve thermal comfort prediction thanks to a better prediction of the different indoor environmental quantities [4] [5].

Preliminary Results and Conclusions

(max 200 words)

The developed model is already able to simulate the three-dimensional heat conduction in a typical cubic room with a refined mesh. The sun patch detection is also successfully implemented.

Regarding the reference validation case, the complex geometry and mesh of the test case are well reproduced. To complete this validation study, current developments focus on the implementation of varying boundary conditions using weather data that vary over short time-steps.

Next step is to couple this thermal model with Computational Fluid Dynamics (CFD) to improve the description of indoor convective transfers at the walls and obtain an accurate and detailed operative temperature map for thermal comfort prediction.

Main References

(max 200 words)

[1] A. Rodler, "Modélisation dynamique tridimensionnelle avec tache solaire pour la simulation du comportement thermique d'un batiment basse consommation," 2014.

[2] E. Arens, H. Zhang and C. Huizenga, "Partial- and whole-body thermal sensation and comfort—Part II: Non-uniform environmental conditions," Journal of Thermal Biology, 2006.

[3] Y. Zhang and R. Zhao, "Relationship between thermal sensation and comfort in non-uniform and dynamic environments," Building and Environment, 2009.

[4] A. Rolder, J. Virgone and J.-J. Roux, "Sun patch impact for the evaluation of operative temperatures distributions," Engineering and Architecture (SCEA), 2014.

[5] A. Rodler, J.-J. Roux, J. Virgone, K. Eui-Jong and J.-L. Hubert, "Are 3D heat tranfer formulations with short time-step and sun patch evolution necessary for building simulation?," Conference paper, 2013.


8:48 - 9:06

Impact of building thermal inertia in different climates using energy dynamic simulation through a simplified description model

Roberto Rugani1, Marco Bigazzi1, Fabio Fantozzi1, Marco Marengo2, Marco Picco2, Giacomo Salvadori1

1University of Pisa, Pisa, Italy; 2University of Brighton, Brighton, United Kingdom

Aim and Approach

(max 200 words)

This study is part of a wider research aimed at creating building type databases for simplified dynamic thermal models of buildings. Among all the factors that influence energy consumption and comfort, the control of internal temperature is undoubtedly the crucial issue [1][2]. The environment temperature variations caused by all the heat exchanges mainly depend on several parameters related to the way the building is designed [3]: the thermal-physical properties of the building materials are surely the main parameters. For many years the quality of building envelopes has been assessed only on the reduction of thermal transmittance [4]; however, recent researches have shown that, especially in order to reduce the need for cooling energy, not only thermal transmittance but also heat capacity should be carefully considered [5]. Thermal inertia causes temporal variations in the heat transfer of external conditions inside the building, and vice versa; although standards such as EN-ISO-13786 allow its impact to be evaluated using semi-stationary methods, the only way to correctly understand its effect is to use dynamic tools. The aim of this project is to evaluate the thermal inertia of the building envelope under different weather conditions, using a simplified dynamic building energy simulation screening tool [6].

Scientific Innovation and Relevance

(max 200 words)

Several building envelopes have been conceived and compared in order to analyse the impact of thermal inertia. Therefore, a database regarding envelope’s constructions and transparent surfaces has been developed to be exhaustive, flexible and modular. This database has then been implemented in a simplified dynamic simulation tool that has been used to evaluate the impact of thermal inertia of different building solutions in the internal comfort of an edifice and in its energy consumption. The tool is based on the well-known building performance simulation program EnergyPlus; and the associated simplified model used has been defined in previous studies by assessing the impact of simplifications on simulation results [7].

The goal of this study is to evaluate the behaviour of different envelopes in two significantly different climate conditions representative of the European climate (London and Brindisi) and for two end uses: residential and office. In order to do so, four comparisons have been identified: envelope with similar transmittance values, but different areal heat capacity; different insulation position in heavyweight envelopes; envelope with similar periodic transmittance values, but different internal heat capacity; and the impact of using PCM boards in lightweight envelopes.

Preliminary Results and Conclusions

(max 200 words)

In order to compare the results of the dynamic energy simulations, a standard building have been defined at geometric level, conceived as a parallelepiped.

Comparisons are based on both thermal comfort and consumption. In particular, in order to evaluate the occupants' internal comfort, operative temperature has been chosen as a suitable parameter (EN-ISO-15251)[8].

From the results can be concluded that thermal inertia has a great relevance, especially in warm climates where energy savings achieved up to 8%. The important role of the internal heat capacity is highlighted by the results of the second and third comparisons, in which, assuming the same periodic transmittance, the envelope with the highest heat capacity has 12% less discomfort levels and 5% less cooling need than the others. In addition, a passive strategy such as a good night-time ventilation during summer has a much more positive impact on high-inertia envelopes, with energy savings up to 17%. However, lightweight envelopes have several advantages, ensuring an adequate level of transmittance with lower thicknesses. Therefore, the analysis has been extended to PCM boards as a solution to improve the dynamic behaviour of lightweight structures, with a tested result of only 1% higher cooling need than the heavyweight envelope.

Main References

(max 200 words)

1. European Parliament Directive 2010/31/EU on the energy performance of buildings. Off. J. Eur. Union 2010.

2. European Parliament Directive (EU) 2018/844 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency. Off. J. Eur. Union 2018.

3. Pacheco, R.; Ordóñez, J.; Martínez, G. Energy efficient design of building: A review. Renew. Sustain. Energy Rev. 2012, 16, 3559–3573, doi:10.1016/j.rser.2012.03.045.

4. Stazi, F. Thermal Inertia in Energy Efficient Building Envelopes; Stazi, F.B.T.-T.I. in E.E.B.E., Ed.; Butterworth-Heinemann, 2017; ISBN 978-0-12-813970-7.

5. Leccese, F.; Salvadori, G.; Asdrubali, F.; Gori, P. Passive thermal behaviour of buildings: Performance of external multi-layered walls and influence of internal walls. Appl. Energy 2018, 225, 1078–1089, doi:10.1016/j.apenergy.2018.05.090.

6. Picco, M.; Marengo, M. A Fast Response Performance Simulation Screening Tool in Support Of Early Stage Building Design. Proc. 16th IBPSA Conf. 2019, 1296–1303, doi:10.26868/25222708.2019.210252.

7. Picco, M.; Marengo, M. Energy simulation in early stage building design: Simplified models and impact on results. Build. Simul. Appl. 2015, 2015-February, 119–126.

8. EN 15251:2007 Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics; 2007;


9:06 - 9:24

Bedroom environmental discomforts, occupant behaviors, and sleep quality based on an online survey

Chenxi Liao1,2, Jelle Laverge1, Mizuho Akimoto3, Chandra Sekhar4, Pawel Wargocki2

1Research group Building Physics, Construction and Climate Control, Department of Architecture and Urban Planning, Ghent University, Belgium; 2International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark; 3Department of Architecture, Waseda University; 4School of Design and Environment, National University of Singapore

Aim and Approach

(max 200 words)

The purpose of this study was to examine the association between discomfort in bedrooms caused by noise, stuffy air, “too warm”, “too cool” conditions, and sleep quality, and the association between occupant behaviors and environmental discomfort in bedrooms, as well as the association between occupant behaviors and sleep quality. An online questionnaire survey was conducted in the summer to investigate the sleep quality of people living in Belgium (temperate climate). It investigated the level of discomfort, if any, and sleep quality. Last but not least, the situation of bedroom environmental discomforts can be used for defining indoor environmental quality in building simulation.

Scientific Innovation and Relevance

(max 200 words)

Bedroom comfort affects sleep quality, which is vital for humans health and next-day performance (Hirshkowitz et al., 2015; Opp, 2009). An increasing number of studies showed the importance of thermal comfort (Imagawa and Rijal, 2015; Lee and Shaman, 2017; Lei et al., 2017), air quality (Laverge and Janssens, 2012; Mishra et al., 2018; Strom-Tejsen et al., 2016), and acoustic comfort (Caddick et al., 2018) for good sleep quality. However, previous studies mainly focused on the effect of only one factor of bedroom environment on sleep quality, although thermal comfort, air quality, and acoustic comfort may influence sleep quality interactively, where at least for thermal comfort and indoor air quality (Xiong et al., 2020). In this study, the frequencies of bedroom environmental discomforts of “too warm”, too cool”, noise and stuffy air, sleep quality (the Pittsburgh Sleep Quality Index (PSQI)), as well as occupant behaviors, were investigated, via an online questionnaire survey in Belgium (temperate climate), from July to August 2020.

Preliminary Results and Conclusions

(max 200 words)

A total of 83 responses was received. The respondents were 43 males and 40 females aged 27 – 32 years. Almost half of the respondents (47.7 %) had a PSQI score greater than 5, which was indicated as poor sleepers. A total of 87.8%, 68.9%, 32.4% and 18.9% of respondents were disturbed regularly or occasionally during sleep by “too warm” conditions, noise, stuffy air and “too cool” conditions, respectively. Responses of people who were disturbed by “too warm” conditions were significantly associated with poor sleep quality; 67.4% of PSQI scores were higher compared to those who were not disturbed (p < 0.05). The PSQI scores increased with the increasing number of bedroom environmental discomforts, the effect being close to significance (p-trend < 0.066). It was concluded that “too warm” conditions were the major bedroom environmental discomfort in summer in Belgium. People experienced poor sleep quality if they were disturbed by more than one of the bedroom environmental discomforts. This study investigated to what extent were people disturbed by thermal discomfort, noise and stuffy air during sleep in summer. More similar studies are required to be conducted in the other three seasons or regions.

Main References

(max 200 words)

Caddick, Z. A., et al., 2018. A review of the environmental parameters necessary for an optimal sleep environment. Building and Environment. 132, 11-20.

Hirshkowitz, M., et al., 2015. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 1, 40-43.

Imagawa, H., Rijal, H. B., 2015. Field survey of the thermal comfort, quality of sleep and typical occupant behaviour in the bedrooms of Japanese houses during the hot and humid season. Architectural Science Review. 58, 11-23.

Laverge J., Janssens A., 2012. Analysis of the influence of ventilation rate on sleep pattern. Indoor Air Conferences. Austin, TX: ISIAQ.

Lee, W. V., Shaman, J., 2017. Heat-coping strategies and bedroom thermal satisfaction in New York City. Science of the Total Environment. 574, 1217-1231.

Lei, Z. P., et al., 2017. Effect of natural ventilation on indoor air quality and thermal comfort in dormitory during winter. Building and Environment. 125, 240-247.

Mishra, A. K., et al., 2018. Window/door opening-mediated bedroom ventilation and its impact on sleep quality of healthy, young adults. Indoor Air. 28, 339-351.

Opp, M. R., 2009. Sleeping to fuel the immune system: mammalian sleep and resistance to parasites. Bmc Evolutionary Biology. 9.



9:24 - 9:42

Phase-change materials selection: numerical study based on design of experiments.

Gilles Baudoin, Geoffrey van Moeseke

Université catholique de Louvain, UCLouvain, Belgium

Aim and Approach

(max 200 words)

Researchers have shown an increased interest in phase-change materials (PCM) to modify thermal mass in buildings. PCM offer an opportunity to increase the thermal mass effect on a given temperature range. A key aspect of PCM selection is the melting temperature but the optimised melting temperature may significantly vary in the literature.

The melting temperature selection could be affected by the properties of the PCM-enhanced component, by the climate and by the building under investigation. To the best of our knowledge, the influence of the building under investigation has never been systematically studied. Therefore, this study aims to quantify the influence of the building parameters on the PCM selection, and more specifically on the optimal melting temperature.

Dynamic simulations of a test-cell in a temperate climate are currently being conducted with EnergyPlus. Various combinations of the building parameters were selected based on design of experiments. For each combination, a case with and without PCM were compared to determine the potential gains of using PCM on energy needs, both for cooling ΔEcool and heating ΔEheat. A metamodel was then constructed to link the energy savings ΔEcool and ΔEheat., with the building parameters in the form of a second order polynomial function.

Scientific Innovation and Relevance

(max 200 words)

To our knowledge, it is the first time that optimal melting temperature is systematically studied for different building parameters. While previous studies were focusing on specific cases, this investigation will allow to generalise the results to a larger set of building configurations.

Knowing the effect of the building parameters on the PCM selection would also allow (i) to facilitate PCM selection in early design phase and (ii) to evaluate the impact of operational conditions on PCM selection. Moreover, this study will provide some support for the original idea of using two different melting temperatures to optimise thermal mass in the building sector. It would allow to identify the best PCM for heating and the one for cooling. In further investigations, combinations of these two PCMs could be compared with the addition of one PCM only.

Preliminary Results and Conclusions

(max 200 words)

Initial results were obtained with eight different building parameters, e.g. wall insulation, and three different PCM-panels. They indicated that: (i) the achievable savings could be higher for cooling than for heating and (ii) an inadequate melting temperature selection could even lead to negative effect for heating. However, these results were not sufficient to identify the different influences of each building parameter on the PCM selection.

The next step is to add the melting temperature in the metamodel. The solution being investigated is to calculate the optimised melting temperature for each combination of parameters, and to build a metamodel for the optimised melting temperature. This metamodel would directly link the optimised melting temperature with the building parameters.

Main References

(max 200 words)

S. E. Kalnæs, B. P. Jelle, Phase change materials and products for building applications: A state-of-the-art review and future research opportunities, Energy and Buildings 94 (2015) 150–176.

P. C. Tabares-Velasco, C. Christensen, M. Bianchi, Verification and validation of EnergyPlus phase change material model for opaque wall assemblies, Building and Environment 54 (2012) 186–196.

M. Saffari, A. de Gracia, S. Ushak, L. F. Cabeza, Economic impact of integrating PCM as passive system in buildings using Fanger comfort model, Energy and Buildings 112 (2016) 159–172.

G. Evola, L. Marletta, F. Sicurella, A methodology for investigating the effectiveness of PCM wallboards for summer thermal comfort in buildings, Building and Environment 59 (2013) 517-527.

M. Mäkelä, Experimental design and response surface methodology in energy applications: A tutorial review, Energy Conversion and Management 151 (2017) 630–640.

S.-G. Yong, J. Kim, J. Cho, J. Koo, Meta-models for building energy loads at an arbitrary location, Journal of Building Engineering 25 (2019) 100823.

P. Westermann, R. Evins, Surrogate modelling for sustainable building design – A review, Energy and Buildings 198 (2019) 170–186.


9:42 - 10:00

Study of the influence of temperature on the moisture buffering capacity of bio-based concretes

Igue Fathia Dahir1, Anh Dung Tran Le1, Alexandra Bourdot2, Promis Geoffrey1, Sy Tuan Nguyen3, Omar Douzane1, Laurent Lahoche1, Thierry Langlet1

1University of Picardie Jules Verne, France; 2Ecole normale supérieure Paris-Saclay, France; 3University of Science and Technology – the University of Danang, Viet Nam

Aim and Approach

(max 200 words)

The aim of this article is investigate the hygric performances of bio-based materials. The MBV value characterizes the ability of a material or multi-layer component to moderate the variation of indoor relative humidity (RH). In the literature, the moisture buffer value was determined at a constant temperature, normally at 23°C. However, in reality, the indoor temperature of the buildings is variable. Therefore, this study will examine the influence of temperature on the moisture buffer value (MBV). First, the physical models are presented. Second, the numerical models have been implemented in the Simulation Problem Analysis and Research Kernel (SPARK) suite to the complex problems. Then, the simulation tools are validated with the experimental results found in the literature. The study will be carried out on a building envelope made of palm and sunflower concretes (bio-based concretes). The boundary conditions of the studied wall are chosen according to the protocol proposed in the NordTest to calculate MBV value as function of temperature. The results showed that the increase in temperature induces an increase in the MBV value. Using this numerical model presented in this paper can predict and optimize the hygric performance of bio-based materials designed for building application.

Scientific Innovation and Relevance

(max 200 words)

Bio-based concretes (such as hemp concrete, flax concrete…) are dedicated to natural construction which is a mean of achieving sustainable construction over time.

In the literature, the moisture buffer value (MBV) was determined at constant temperature, 23°C. However, in reality, the indoor temperature of the buildings is variable. The experimental results showed that the MBV value is impacted by the temperature. For example, MBV values of palm concrete measured at 23°C and 10°C are 2.96 and 2.03 (g.m-2. % RH-1) respectively (with a percentage deviation of 31.42 %). Therefore, it is necessary to carry out an in-depth study on the impact of temperature on the MBV value of bio-based materials.

The use of the presented numerical model which has been validated experimentally can predict and optimize the hygric performance of bio-based materials designed for building application.

Preliminary Results and Conclusions

(max 200 words)

The numerical model to study the influence of temperature on the MBV value has been validated by comparing with the results found in the literature.

The preliminary results showed that the increase in temperature induces an increase in the MBV value and using the numerical model presented in this paper can predict and optimize the hygric performance of bio-based materials.

Main References

(max 200 words)

Chennouf, N., Agoudil, B. 2018. « Hygrothermal characterization of a new bio-based construction material: Concrete reinforced with date palm fibers ». Construction and Building Materials (192): 382-394.

Janssen, H., Roels, S. 2009. « Qualitative and quantitative assessment of interior moisture buffering by enclosures ». Energy and Building 41 (4): 382-394. doi: 10.1016/j.enbuild.2008.11.007.

Philip, J.R., De Vries, D.A. 1957. « Moisture movement in porous materials under temperature gradients ». Transaction of American Geophysical Union 38 (2): 222–232.

Rode, C., Peuhkuri, R., Lone, H., Time, B., Gustavsen, A., Ojanen, T., Ahonen, J., Svennberg, K. « 2005. Moisture buffering of building materials ». Nordic Innovation Centre Report: BYG-DTU R-126: 1601–2917.

Tran Le, A.D. 2010. « Etude des transferts hygrothermiques dans le béton de chanvre et leur application au bâtiment (sous-titre: simulation numérique et approche expérimentale) ». Thèse de doctorat, Reims : Université de Reims Champagne-Ardenne.

31084_Fathia Dahir_Igue.pdf

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