Using Thermostats for Indoor Climate Control in Offices: The Effect on Thermal Comfort and Heating/Cooling Energy Use

Haiying Wang*, Bjarne W. Olesen, Ongun Berk Kazanci

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

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Abstract

The most commonly used thermostat control variable in heating, ventilating and air-conditioning systems is air temperature. However, people's thermal comfort responds to operative temperature more directly than air temperature. Will the adoption of operative temperature based control lead to better thermal comfort and how will this affect the energy use? To get a better understanding about these questions, simulations have been performed based on three heating and cooling systems in three different geographical locations (Copenhagen, Paris and Rome). The three system are fan-coil system representing convective system and two radiant systems: floor heating/cooling system and radiant ceiling heating/cooling panel system.The results showed that air temperature based thermostat control and operative temperature based thermostat control had different impacts on fan-coil system and radiant systems. For fan-coil system, the use of operative temperature based thermostat control had better thermal comfort conditions and higher energy use than that of air temperature based thermostat control. For the two radiant systems, the results were the opposite. The results were almost the same in different locations. Besides, the thermal comfort difference between the two controls of north office was smaller than that of south office. For fan-coil system, in south office, compared with air temperature based thermostat control, the hours of Cat. I (-0.2≤PMV≤0.2) increased 8.3% for building in Copenhagen, 8.8% for Paris and 14.2% for Rome and hours of Cat. IV (PMV<-0.7 or PMV>0.7) decreased 2.5%, 3.9% and 7.1% respectively when operative temperature based thermostat control was used. Meanwhile, total energy supply increased 13.7% in Copenhagen, 14.3% in Paris and 12.7% in Rome. For radiant systems, the total energy use reduced 3.3% to 8.3% depending on location and type of system when operative temperature based control was used. With this reduction of energy use, thermal comfort in south office was still within recommended criteria in international standards in most cases. Based on the results, it is suggested that air temperature based thermostat control be used in fan-coil system and operative temperature based thermostat control be used in radiant system in north office. For south office, operative temperature based thermostat control was considered better for fan-coil system and could be more energy efficient when utilized in radiant heating and cooling systems.
Original languageEnglish
JournalEnergy and Buildings
Volume188-189
Pages (from-to)71-83
ISSN0378-7788
DOIs
Publication statusPublished - 2019

Keywords

  • Room temperature contro
  • Air temperature
  • Operative temperature
  • Energy use
  • Thermal comfort
  • Heating/cooling system
  • Convective system
  • Radiant system

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