Abstract
Recently accepted revisions to ASHRAE Standard 55—thermal environmental conditions for human occupancy, include a new adaptive comfort standard (ACS) that allows warmer indoor temperatures for naturally ventilated buildings during summer and in warmer climate zones. The ACS is based on the analysis of 21,000 sets of raw data compiled from field studies in 160 buildings located on four continents in varied climatic zones. This paper summarizes this earlier adaptive comfort research, presents some of its findings for naturally ventilated buildings, and discusses the process of getting the ACS incorporated into Standard 55. We suggest ways the ACS could be used for the design, operation, or evaluation of buildings, and for research applications. We also use GIS mapping techniques to examine the energy-savings potential of the ACS on a regional scale across the US. Finally, we discuss related new directions for researchers and practitioners involved in the design of buildings and their environmental control systems.
Highlights
The purpose of ASHRAE Standard 55—thermal environmental conditions for human occupancy, is ‘‘to specify the combinations of indoor space environment and personal factors that will produce thermal environmental conditions acceptable to 80% or more of the occupants within a space’’ [1]
While ‘‘acceptability’’ is never precisely defined by the standard, it is commonly agreed within the thermal comfort research community that ‘‘acceptable’’ is synonymous with ‘‘satisfaction’’, and that ‘‘satisfaction’’ is associated with thermal sensations of ‘‘slightly warm’’, ‘‘neutral’’, and ‘‘slightly cool’’. ‘‘Thermal sensation’’ is the question most commonly asked in both laboratory and field studies of thermal comfort
Influences peoples’ thermal sensations? ASHRAE Standard 55 is currently based on the heat balance model of the human body, which assumes that thermal sensation is exclusively influenced by four environmental factors, and two personal factors
Summary
The purpose of ASHRAE Standard 55—thermal environmental conditions for human occupancy, is ‘‘to specify the combinations of indoor space environment and personal factors that will produce thermal environmental conditions acceptable to 80% or more of the occupants within a space’’ [1]. While the heat balance model is able to account for some degrees of behavioral adaptation such as changing one’s clothing or adjusting local air velocity, it ignores the psychological dimension of adaptation, which may be important in contexts where people’s interactions with the environment (i.e. personal thermal control), or diverse thermal experiences, may alter their expectations, and their thermal sensation and satisfaction One context where these factors play a important role is naturally ventilated buildings—the focus of this paper. People who live or work in naturally ventilated buildings where they are able to open windows, become used to thermal diversity that reflects local patterns of daily and seasonal climate variability Their thermal perceptions— both preferences as well as tolerances—are likely to extend over a wider range of temperatures than are currently reflected in the old ASHRAE Standard 55 comfort zone. For greater detail about the background research, previous papers describe the results of our literature search on thermal adaptation [3], the specific procedures for developing the database [4], and our analysis methods and findings [5,6]
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