Feasibility study of indoor temperature setting at 25.5 oC for energy saving

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Feasibility study of indoor temperature setting at 25.5 oC for energy saving


Author: Wang, Rui
Title: Feasibility study of indoor temperature setting at 25.5 oC for energy saving
Degree: M.Eng.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Buildings -- Energy conservation.
Air conditioning.
Human comfort.
Department: Dept. of Building Services Engineering
Pages: viii, 93 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2303477
URI: http://theses.lib.polyu.edu.hk/handle/200/4786
Abstract: Nowadays, energy saving is a worldwide issue. In an education institution, HVAC system energy consumption takes up a large portion of the whole institute's energy consumption. In Hong Kong, about one-third of the electricity consumed is used for air-conditioning. It is very common to find that people need to wear extra clothing in air-conditioned premises in summer because the temperature is set too low, which is consumptive obviously. Consequently, the Electrical and Mechanical Services Department (EMSD) advocate "setting air-conditioned room temperature to 25.5 oC". The government admits that 25.5 oC might not be everyone's preferred temperature, but it is high enough to save a substantial amount of cooling energy. This study presents the findings of an investigation into the feasibility of maintaining room temperature at 25.5 oC in buildings in education institutions by measuring thermal comfort sensation of the occupants. Therefore, this study had a practical purpose: to investigate whether the thermal comfort can be achieved when the indoor room temperature is set at 25.5 oC by reviewing the related fundamental knowledges about thermal comfort and by survey occupants' perception. Relevant data were collected by means of site measurement and questionnaire survey of 30 participants who were studying at PolyU. Moreover, the PMV-PPD model and ASHRAE Thermal Comfort tool program software were also put into use to link up the questionnaire survey results. Finally, it was found that the majority of the respondents could accept the environmental thermal condition when the room temperature was set at 25.5 oC if their clothing value was adjusted to 0.5 more or less. From the sample calculation for energy saving, it could be concluded that the energy saving of 7% for air conditioning system can be achieved if the setpoint of indoor room temperature was changed from 24 oC to 25.5 oC. Considering that most occupants felt slightly cool when they were wearing normal summer clothes at 24 oC, it is suggested that the room temperature should be set at a higher point for energy conservation. However, due to the small sample size and short period of the site measurement and so on, further study will be considered carefully.

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