COMPARISON OF INDOOR AIR TEMPERATURE AND OPERATIVE TEMPERATURE -DRIVEN HVAC SYSTEMS BY MEANS OF THERMAL COMFORT AND ENERGY CONSUMPTION

Öz

The main purpose of Heating, Ventilating and Air-Conditioning (HVAC) systems is to satisfy thermal comfort for the occupants. Conventionally, HVAC systems adjust set-temperature to achieve thermal comfort by continuously measuring indoor air temperature of the environment. However, ASHRAE 55, a standard of acceptable thermal environments, offers to use acceptable ranges of operative temperatures in air-conditioned buildings. Considering operative temperature is a function of indoor air temperature and mean radiant temperature, set-temperature of HVAC system can be controlled by using operative temperature to satisfy neutral thermal comfort for the occupants. This study compares thermal comfort and energy consumption of two exactly same HVAC systems which are operated based on indoor air temperature and operative temperature, respectively. Two office rooms with same architectural configurations -which are located in a university-Ankara-Turkey- were selected as a case study. The HVAC systems were operated based on indoor air temperature and operative temperature, respectively, at the same time and occupancy schedules. The results showed that operative temperature driven controlled HVAC system achieves better thermal comfort while slightly increasing energy consumption. The main findings of this study would be useful not only to design energy-efficient HVAC systems but also create more comfortable environments.

Anahtar Kelimeler

• Thermal Comfort,Operative Temperature,HVAC System Control,Energy Consumption

Kaynakça

1. [1] ASHRAE 55, Thermal Environment Conditions for Human Occupancy, 2017.
2. [2] ISO 7730, Moderate Thermal Environments- Determination of the PMV and PPD indices and Specification of the Conditions for Thermal Comfort, International Standards Organization, 1995.
3. [3] Fanger, P., Thermal Comfort, Danish Technical Press, Copenhagen, 1970.
4. [4] Calvino, M., Gennusa, M.L., Morale, M., Rizzo, G. and Scaccianoce, G., “Comparing Different Control Strategies for Indoor Thermal Comfort Aimed at the Evaluation of the Energy Cost Quality of the Building”, Journal of Process Control, 24 (6), 703-713, 2014.
5. [5] Oktay, H., Argunhan, Z., Yumrutaş, Y., Işık, M.Z. and Budak, N., “An Investigation of the Influence of Thermophysical Properties of Multilayer Walls and Roofs on the Dynamic Thermal Characteristics”, Muğla Journal of Science and Technology, 2 (1), 48-54, 2016.
6. [6] Wu, Z., Li, N., Wargocki, P., Peng, J., Li, J. and Cui, H., “Adaptive Thermal Comfort in Naturally Ventilated Dormitory Buildings in Changsha, China”, Energy and Buildings, 186, 56-70, 2019.
7. [7] Becchio, C., Corgnati, S.F., Vio, M., Crespi, G., Prendin, L., Ranieri, M. and Vidotto, D., “Toward NZEB by optimizing HVAC system configuration in different climates”, Energy Procedia, 140, 115-126, 2017.
8. [8] Kwok, A.G. and Chun, C., “Thermal Comfort in Japanese Schools”, Solar Energy, 74 (3), 245-252, 2003.

9. [9] Nicol, F. and Humpreys, M., “Derivation of the Adaptive Equations for Thermal Comfort in Free-Running Buildings in European Standard EN15251”, Building and Environment, 45 (1), 11-17, 2010.
10. [10] Wong, N.H. and Khoo, S.S., “Thermal Comfort in Classrooms in the Tropics”, Energy and Buildings, 35 (4), 337-351, 2003.
11. [11] Atmaca, I., Kaynaklı, Ö. and Yiğit, A., “Effects of Radiant Temperature on Thermal Comfort”, Building and Environment, 42 (9), 3210-3220, 2007.
12. [12] Turhan, C., Simani, S., Zajic, I. and Gökçen Akkurt, G., “Performance Analysis of Data-Driven and Model-based Control Strategies Applied to a Thermal Unit Model, Energies, 10 (1), 67, 2017.
13. [13] Kusiak, A., Tang, F. and Xu, G., “Multi-objective Optimization of HVAC system with an Evolutionary Computational Algorithm”, Energy, 36, 2440-2449, 2011.
14. [14] Jain, V., Garg, V., Mathur, J. and Dhaka, J.,”Effect of Operative Temperature Based Thermostat Control as Compared to Air Temperature Based Control on Energy Consumption in Highly Glazed Buildings”, Proceedings of Building Simulation, 1, 2687-2695, 2011.
15. [15] Olesen, B.W., Wang, H., Kazancı, O.B. and Coakley, D., “The Effect of Room Temperature Control by Air- or Operative Temperature on Thermal Comfort and Energy Use” Proceedings of Building Simulation, 1, 1-8, 2019.
16. [16] Wang, H., Olesen, B.W. and Kazancı, O.B., “Using Thermostats for Indoor Climate Control in Offices: The Effect on Thermal Comfort and Heating/Cooling Energy Use, Energy and Buildings, 188, 71-83, 2019.
17. [17] Niu, J.I. and Burnett, J., “Integrating Radiant/ Operative Temperature Controls into Building Energy Simulations”, ASHRAE Transactions, 104 (2), 210-217, 1998.
18. [18] Turhan, C. and Gökçen Akkurt, G., “Assessment of Thermal Comfort Preferences in Mediterranean Climate: A University Office Building Case”, Thermal Science, 22 (5), 2177-2187, 2018.
19. [19] Köppen-Geiger Climate Classification, 2009.
20. [20] Turkish State Meteorological Service, 2019.