Comfort and discomfort criteria
1. Introduction
Thermal comfort in the building is an essential requirement. What differentiates modern architecture in terms of the energy problem from the architecture of any era is not only the reduction in the availability of energy resources but rather the demand for thermal comfort.
Energy optimization in buildings is considered a major area of interest in the modern era of scientific research. Energy consumption in buildings has increased from \(24\%\) to \(40\%\) in developed countries. A significant amount of this energy is used to provide a sufficient level of comfort for the building’s occupants. Moreover, given recent increases in global temperatures due to climate change and the associated decrease in comfort levels, it is increasingly important to provide adequate levels of comfort in indoor spaces. However, finding a balance between reducing the energy consumption of buildings and providing adequate levels of comfort is a major challenge (cf.[Gilani2015])
According to ASHRAE Standard 55, thermal comfort is defined as the condition of mind that expresses satisfaction with the thermal environment and is estimated by subjective evaluation. The World Health Organization (WHO) also defines thermal comfort as the condition when people are satisfied with the thermal environment. There are two well-known thermal comfort models that are used internationally to establish the thermal comfort conditions in a building(cf.[Sarah2015]):
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Fanger Model
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Adaptive model .
During our internship, we became interested in the Fanger Model which is a static approach based on the thermal equilibrium of the human body by introducing two indices: the predicted mean Vote (PMV) and the predicted percentage of dissatisfied (PPD). To get more informations about the comfort thermique, you can follow the link.
2. Model
Within the framework of our internship we are interested in the study of thermal comfort of the building located in Illkirch studied in 4 fastsim-ibat project.
2.1. Validation
The first step of our study consists in implementing a general thermal comfort model, in which we have calculated the PPMV and pdd indices whose parameter values are given according to the norm ISO 77033.
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\(M\) [\(\text{W}/\text{m}^2\)] : the metabolic rate.
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\(W\) [\(\text{W}/\text{m}^2\)] : the effective mechanical power ( W=0).
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\(I_{cl}\) [\(\text{m}^2\text{K}/\text{W}\)] : the clothing insulation
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\(f_{cl}\) [–] : the clothing surface area factor :
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\(T_a\) [°C] : the air temperature
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\(T_{mr}\) [°C] : the mean radiant temperature
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\(v_{ar}\) [m/s] : the relative air velocity
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\(p_a\) [Pa] : the water vapor partial pressure
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\(h_c\) [\(\text{W}\,\text{m}^{-2}\text{K}^{-1}\)] : the convective heat transfer coefficient with :
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\(T_{cl}\) [°C] : the clothing surface temperature
To verify the efficiency and performance of the previous model we will compare the results we have obtained with the results of the table given according to the norm ISO 77033.
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| Run no. | \(T_a\) (°C) | \(T_{mr}\) (°C) | \(v_{ar}\) (m/s) | RH (%) | M (met) | \(I_{cl}\) (clo) | PMV | PPD | Calculated PMV | Calculated PPD | Verify |
|---|---|---|---|---|---|---|---|---|---|---|---|
1 |
22.0 |
22.0 |
0.1 |
60 |
1.2 |
0.5 |
-0.75 |
17 |
-0.75 |
16.85 |
correct value |
2 |
27.0 |
27.0 |
0.1 |
60 |
1.2 |
0.5 |
0.77 |
17 |
0.76 |
17.17 |
correct value |
3 |
27.0 |
27.0 |
0.3 |
60 |
1.2 |
0.5 |
0.44 |
9 |
0.43 |
8.86 |
correct value |
4 |
23.5 |
25.5 |
0.1 |
60 |
1.2 |
0.5 |
-0.01 |
5 |
-0.02 |
5.01 |
correct value |
5 |
23.5 |
25.5 |
0.3 |
60 |
1.2 |
0.5 |
-0.55 |
11 |
-0.56 |
11.57 |
correct value |
6 |
19.0 |
19.0 |
0.1 |
40 |
1.2 |
1.0 |
-0.6 |
13 |
-0.61 |
12.80 |
correct value |
7 |
23.5 |
23.5 |
0.1 |
40 |
1.2 |
1.0 |
0.5 |
10 |
0.36 |
7.70 |
incorrect value |
8 |
23.5 |
23.5 |
0.3 |
40 |
1.2 |
1.0 |
0.12 |
5 |
0.11 |
5.25 |
correct value |
9 |
23.0 |
21.0 |
0.1 |
40 |
1.2 |
1.0 |
0.05 |
5 |
0.05 |
5.05 |
correct value |
10 |
23.0 |
21.0 |
0.3 |
40 |
1.2 |
1.0 |
-0.16 |
6 |
-.17 |
5.60 |
correct value |
11 |
22.0 |
22.0 |
0.1 |
60 |
1.6 |
0.5 |
0.05 |
5 |
0.04 |
5.03 |
correct value |
12 |
27.0 |
27.0 |
0.1 |
60 |
1.6 |
0.5 |
1.17 |
34 |
1.17 |
33.79 |
correct value |
13 |
27.0 |
27.0 |
0.3 |
60 |
1.6 |
0.5 |
0.95 |
24 |
0.95 |
24.06 |
correct value |
|
For the case 7, we did not find the same results, it could be a typing error in the results of the table given by the nome ISO 77033. |
2.2. Application
To calculate the comfort of the building we will proceed as follows: use the values obtained by the captors installed in the building and for the parameters not calculated by the captors we will modify their value so that they are consistent with the building configuration.
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Metabolic rate (\(M\))
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Effective mechanical power (W=0).
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Clothing insulation (\(I_{cl}\)) equal to \(0.5\) clo in summer and \(1.0\) clo in winter.
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Clothing surface area factor (\(f_{cl}\))
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Air temperature (\(T_a\)) (calculated by captors)
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Mean radiant temperature (\(T_{mr}\))
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Relative air velocity (\(v_{ar}\))
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Water vapor partial pressure (\(p_a\))
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Convective heat transfer coefficient(\(h_c\) )
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Clothing surface temperature (\(T_{cl}\))
References
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[Allab17] Allab, Yacine. Building ventilation performance assessement : ventilation efficiency and thermal comforT. PhD thesis, École nationale supérieure d’arts et métiers, 2017
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[ASHRAE2004] ANSI/ASHRAE Standard 55. Thermal Environment Conditions for Human Occupancy, 2004.
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[Candas2000] Candas, V., Traité Génie énergeétique, Techniques de l’Ingénieur, Doc. BE 9 085, 2000.
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[Cannistraro1992] Cannistraro, G., Franzitta, G., and Giaconia, C., Algorithms for the calculation of the view factors between human body and rectangular surfaces in parallelepiped environments, Energy and Buildings, 19(1992) 51-60
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[Djongyang2010] Djongyang, N., Tchinda, R., and Njomo, D. Thermal comfort: A review paper, Renewable and Sustainable Energy Reviews 14 (2010) 2626–2640.
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[Gilani2015] Syed Ihtsham ul Haq Gilani, Muhammad Hammad Khan and William Pao, Thermal comfort analysis of PMV model Prediction in Air conditioned and Naturally Ventilated Buildings,2015.
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[Hensen1991] Hensen J. L. M., On the thermal interaction of building structure and heating and ventilating system, PhD thesis, Technische Universiteit Eindhoven; 1991. Download PDF
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[ISO-7730] Ergonomics of the thermal environment — Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria
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[Sarah2015] Sarah Benharkat and Djamila Rouag-Saffidine, Approche adaptative du confort thermique dans les espaces d’enseignement universitaire à Constantine,2015