TY - JOUR
T1 - Mixed-mode buildings
T2 - A double standard in occupants' comfort expectations
AU - Deuble, Max Paul
AU - de Dear, Richard John
PY - 2012/8
Y1 - 2012/8
N2 - This paper investigates how mixed-mode (MM) ventilation affects occupant comfort by presenting results from a longitudinal field study within an academic office building from a tertiary educational institution in sub-tropical Sydney, Australia. The building automatically switches into air-conditioned (AC) mode whenever indoor temperatures exceed 25 °C. Coincident indoor and outdoor climate measurements along with 1359 subjective comfort questionnaires were collected. Thermal sensations during natural ventilation did not conform to those predicted using Fanger's PMV-PPD [1]. Differences in thermal perception were also apparent between these two modes. Within AC mode, a PMV = +1 environment elicited much 'warmer-than-neutral' thermal sensations than the same PMV = +1 environment within naturally-ventilated (NV) mode, suggesting thermal subjective perceptions were affected by the building's mode of operation over and above the objective indoor climatic conditions. These discrepancies emphasize the complexity of thermal perception and the inadequacy of using PMV models to describe occupant comfort in MM buildings. ASHRAE's Standard 55 [2] currently classifies MM buildings as AC buildings, and as such, limits the operation of these buildings to the more restrictive PMV-PPD range of indoor thermal conditions. In contrast, EN15251 [3] permits the more flexible adaptive comfort standard to be applied to buildings operating under NV mode. Results from this study favour EN15251's application of the adaptive comfort model instead of PMV-PPD to MM buildings when they are operating in NV mode.
AB - This paper investigates how mixed-mode (MM) ventilation affects occupant comfort by presenting results from a longitudinal field study within an academic office building from a tertiary educational institution in sub-tropical Sydney, Australia. The building automatically switches into air-conditioned (AC) mode whenever indoor temperatures exceed 25 °C. Coincident indoor and outdoor climate measurements along with 1359 subjective comfort questionnaires were collected. Thermal sensations during natural ventilation did not conform to those predicted using Fanger's PMV-PPD [1]. Differences in thermal perception were also apparent between these two modes. Within AC mode, a PMV = +1 environment elicited much 'warmer-than-neutral' thermal sensations than the same PMV = +1 environment within naturally-ventilated (NV) mode, suggesting thermal subjective perceptions were affected by the building's mode of operation over and above the objective indoor climatic conditions. These discrepancies emphasize the complexity of thermal perception and the inadequacy of using PMV models to describe occupant comfort in MM buildings. ASHRAE's Standard 55 [2] currently classifies MM buildings as AC buildings, and as such, limits the operation of these buildings to the more restrictive PMV-PPD range of indoor thermal conditions. In contrast, EN15251 [3] permits the more flexible adaptive comfort standard to be applied to buildings operating under NV mode. Results from this study favour EN15251's application of the adaptive comfort model instead of PMV-PPD to MM buildings when they are operating in NV mode.
KW - Adaptive comfort standards
KW - Adaptive model
KW - Mixed-mode ventilation
KW - Thermal comfort
UR - http://www.scopus.com/inward/record.url?scp=84857516602&partnerID=8YFLogxK
U2 - 10.1016/j.buildenv.2012.01.021
DO - 10.1016/j.buildenv.2012.01.021
M3 - Article
AN - SCOPUS:84857516602
SN - 0360-1323
VL - 54
SP - 53
EP - 60
JO - Building and Environment
JF - Building and Environment
ER -