Online & Oslo, Norway
21-23 June 2021
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Please note that all times are shown in the time zone of the conference. The current conference time is: 29th July 2021, 03:30:41am CEST
Session 12: Numerical simulation
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10:30am - 10:42am
Can we measure buildings' affordance?
TU Wien, Austria
The term affordance is used in this paper to denote the capacity of buildings to provide occupants the possibility to control the indoor-environmental conditions so as to meet their needs and requirements. This is typically facilitated via buildings’ various control devices and systems meant to control ambient conditions. In this paper, we discuss recent progress in developing a building affordance evaluation method. The idea is to evaluate buildings’ control devices and elements based on their availability as well as their effectiveness. We critically examine the strengths and weaknesses of the proposed affordance measurement method and discuss its future potential to be used as a performance assessment tool by professionals and stakeholders in building design and operation.
10:42am - 10:47am
CFD simulation of non-isothermal ventilation flow in a generic enclosure: Impact of inlet velocity boundary conditions
Building Physics and Services, Department of the Built Environment, Eindhoven University of Technology, P.O. box 513, 5600 MB Eindhoven, The Netherlands
Computational fluid dynamics (CFD) simulations are widely used in the prediction of indoor airflow in enclosed spaces. In most past studies, due to the absence of experimental data at air supply openings or for the sake of simplification, uniform hypotheses of inlet boundary conditions for velocity, temperature, and turbulence parameters were commonly applied. However, when aiming for an accurate simulation of indoor ventilation flows with buoyancy effects and complex geometry of the air supply system, the uniform settings at the inlet boundaries can be insufficient, even with a highly accurate simulation approach such as large eddy simulation (LES).
In this study, CFD simulations of non-isothermal ventilation flow in a generic closure are performed. To find the proper settings of inlet boundary conditions, a high-quality indoor ventilation experiment with detailed information of all relevant parameters near the air supply openings is used. Three different methods of generating inlet boundary quantities from the experimental data are tested, which are the methods of (1) uniform quantities, (2) fitting profiles, and (3) prescribing values. Simulation results demonstrate that for the definition of the velocity at the inlet only the last method, i.e. using available experimental data to prescribe detailed values at the inlet, can provide a good agreement between numerical results and experimental results throughout the studied enclosure. In addition, the current work shows that the inlet boundary conditions of turbulence quantities can also have significant effects on the simulation results of room airflow.
It is recommended that for future CFD validation studies the measured data near the air supply opening, if available, is directly applied as the inlet boundary conditions, especially when the geometry of air supply system is complex. In addition, special care should be taken when imposing the inlet turbulent parameters since these can strongly affect the comparison with experimental data. Finally, if possible, experimental data sets generated for CFD validation should include detailed measurements of all relevant quantities near the inlet to avoid a biased conclusion on the performance of turbulence models and other computational settings.
10:47am - 10:59am
Numerical simulation and field survey research of indoor thermal comfort for healthy building: A case study of Lingnan residential building
1School of Architecture, South China University of Technology; 2Architectural Design & Research Institute Co., Ltd, South China University of Technology; 3State Key Laboratory of Subtropical Building Science, South China University of Technology; 4Department of Urban Planning and Design, Faculty of Architecture, The University of Hong Kong; 5Tsinghua Shenzhen International Graduate School, Tsinghua University; 6Faculty of Architecture and the Built Environment, Delft University of Technology
Due to COVID-19, people spend more and more time indoors. Healthy buildings, therefore, become more attractive to people than ever before. By summarizing specific requirements on relevant standards for healthy indoor thermal condition, this paper adopts numerical simulation and field survey to study indoor thermal comfort with a Lingnan residential building as a study case. After optimizing by building design strategy, the research results show that (1) The numerical simulation method could be used for evaluating indoor thermal comfort based on Ladybug and Honeybee plugins. The results have the same trend as the field survey. (2) Yuedao Courtyard did not meet healthy indoor thermal environment requirements under natural ventilation. It is hot indoors, whatever during the whole year simulation or on the measurement day. (3) The optimization measures could be considered by adding sunshades on the windows under the passive building context. It can be universally used for the standard building which entrance faced west. (4) Numerical simulation is almost not restricted by working conditions, especially for buildings under design, which can evaluate whether the indoor thermal comfort condition is healthy or not. It is useful for designers to solve practical problems for better design.
10:59am - 11:11am
Numerical Simulation of Double Skin Facade used to produce Energy in Buildings
1FCT – University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; 2CINTAL, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; 3School of Construction Management & Engineering, University of Reading, Reading, RG6, 6AW, United Kingdom
This article introduces a numerical model to project and construct a Double Skin Facade (DSF) in windows facing south, in order to be used on thermal energy generation in winter conditions. The DSF system is applied to a virtual chamber similar to a real experimental chamber and it is connected to a mixing ventilation system. The thermal energy generated by this DSF system is used to further indoor air quality and thermal comfort for occupants. The numerical simulation is done by a software that simulates the virtual chamber and the DSF thermal response. This software uses energy and mass balance integral equations for the opaque surfaces, transparent surfaces and internal air. It also considers the solar radiation simulator, the glass radiative properties and the assessment of radiative and convective coefficients. The results show that the proposed DSF system, using solar radiation, contributes to having acceptable conditions of thermal comfort, during most of the occupation cycle, and indoor air quality.
11:11am - 11:16am
Numerical study of the influence of balconies on indoor environment in winter: A case study of college dormitories in Jinan, China
1School of Thermal Engineering, Shandong Jianzhu University, Jinan 250101, China; 2Shandong GRAD Built Environment Design and Research Institute Co., Ltd, Dezhou, 253000, China
The ventilation rate of dormitory in winter affects the living quality and learning state of students, while the balcony will affect the indoor ventilation of dormitory. In order to explore the influence of different locations, floor heights and building types on the ventilation rate and indoor environment of the dormitory in winter, this paper used the computational fluid dynamics software PHOENCIS and the multi-area network model software CONTAM coupling calculation method to simulate the indoor ventilation conditions of the dormitory in a university with or without balconies under three building types. The results show that the average ventilation volume with balcony is 44.04 m3/h lower than that without balcony. When there are balconies, the room ventilation rate of the first floor of ordinary rectangular building, the second floor of L-type building and the first floor of rectangular-ambulatory-plane building are the largest. The room ventilation rate of different positions on the same floor of ordinary rectangular building is the lowest. Considering comprehensively, it is better to choose rectangular-ambulatory-plane dormitory buildings when there is a balcony.
11:16am - 11:28am
INCHEM-Py: A new open source model for investigating indoor air chemistry
University of York, United Kingdom
The new INdoor CHEMical model (INCHEM-Py) is a python refactor and development of the internationally recognised INdoor Detailed Chemical Model (INDCM). It is an open source and accessible 1D box model that examines the complex air chemistry of indoor environments. The unique element in this model is the incorporation of an explicit chemical mechanism that considers the step by step degradation of around 150 common volatile organic compounds. The model also considers indoor photolysis (combination of attenuated outdoor plus artificial lighting), exchange with outdoor air, and emissions from/deposition to surfaces. The chemical detail allows the user to understand key reaction pathways and identify the species that accumulate to high concentrations for a range of conditions that are commonly encountered indoors.
The methods used and assumptions made within INCHEM-Py will be described alongside a walkthrough of the solution process. Benchmarking results will be examined and compared to published work. Additional features that were not implemented in the INDCM will also be discussed and linked to the comprehensive documentation designed to aid users and enable efficient scientific progress. Preset scenarios (e.g. cooking and cleaning events) will be demonstrated with outputs compared to available experimental data.
Due to the nature of open source models, INCHEM-Py provides a solid base for future work in the indoor air community, for users of all abilities. Confident users can edit the model to run their own tailored scenarios, but there is also the option to use pre-set scenarios for which only slight modifications are required. We also hope that users will make or suggest future improvements, so INCHEM-Py continues to be relevant. We look forward to continuing our collaboration with a growing community of indoor air scientists, nurturing a collaborative model development environment.
11:28am - 11:40am
Identification of most important factors (Building factors: artificial lights and window materials; External factors: cloud factors, season, latitude) affecting indoor photolysis rates
University of York, United Kingdom
The importance of photolysis for outdoor air chemistry is well established, but the role of indoor photolysis is less well studied and hence quantified. Although photolysis is diminished indoors (e.g.by glass in windows and coverings on light sources), it still occurs, particularly for reactions that occur at longer wavelengths. Indoor lights include artificial lights and attenuated sunlight that can move into indoor environments through windows and skylights. The amount of light that can penetrate indoors is influenced by many factors, including the type of window, meteorological conditions and the building alignment and location. The aim of this paper is to investigate the impacts of cloud, latitude, season, window material and artificial light on indoor air chemistry. The model used in this work is the INDCM (INdoor Detailed Chemical Model), a near explicit box model which uses a comprehensive chemical mechanism. This mechanism has approximately 20,000 reactions and 5,000 species and represents the degradation of ~143 volatile organic compounds in the gas-phase. The degradation of each VOC is initiated by the reaction with radicals, including NO3, OH and O3, and photolysis where relevant. The process continues until H2O and CO2 are formed as the final oxidation products. The INDCM also includes terms that consider exchange with outdoors, internal emissions, photolysis and deposition to surfaces.
This paper compares the impacts of two building factors (different artificial lights indoors and window materials) and three external factors (cloudiness, time of year and latitude) on indoor photolysis rates, in order to find out the most important controls for the resulting indoor air chemistry. The results show that latitude and time of year are the most important factors affecting indoor radical concentrations, followed by cloudiness and window material. Different artificial lights typically have a smaller impact, although fluorescent lighting can impact radical concentrations under some conditions. Our results show that depending on where a building is situated and the time of year, indoor air chemistry may be quite different.
11:40am - 11:45am
Development of an underground space using to produced cold energy in summer conditions in the building thermal conditions performance
1FCT - University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; 2CINTAL, Campus de Gambelas, 8005-139 Faro, Portugal;; 3School of Construction Management & Engineering, University of Reading, Reading, RG6, 6AW, United Kingdom
The aim of this numerical work is the application of underground spaces and Dual Skin Facades (DSF) to improve comfort conditions in a virtual chamber. This virtual chamber, similar to a real experimental chamber, is equipped with an underground space and three DSF installed in front of windows located in the southern surroundings. A numerical model that simulates the Building Dynamic Response is used. This model considers an energy and mass balance integral equations system used to estimate the air temperature and the mass of contaminants inside the virtual chamber and DSF and the temperature in the different elements of the virtual chamber and DSF. The evolution of the air temperature of the virtual chamber, DSF and spaces are obtained and indoor air quality and thermal comfort level are evaluated. The indoor air quality level is acceptable and the thermal comfort level is acceptable according to the international standards recommendations.
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