WORLD – A recent study carried out by scientists Boris Kingma and Wouten van Marken Lichtenbelt has suggested that a gender bias exists when companies calculate the thermal comfort of house occupants. The study is one that could have far-reaching consequences for the HVAC industry.
The study states that indoor climate regulations are based on an empirical thermal comfort model that was developed in the 1960s and that one of its primary variables, metabolic rate, is based on that of an average male, and may overestimate female metabolic rate by up to 35%. This discrepancy may result in buildings being intrinsically non-energy-efficient in providing comfort for females. The study used a biophysical analysis to illustrate the effect of miscalculating metabolic rate on female thermal demand.
The premise of the study was that today there is an ever-greater focus on the design of energy-efficient buildings which aims to deliver an indoor climate which satisfies the thermal demands of all occupants. If the indoor climate is not adapted to all the occupants, then those occupants are liable to change their behaviour in order to optimise their own personal comfort which can, in turn, negate the effects of supposedly energy-efficient building designs.
The study states that in general women prefer warmer temperatures at home or in the workplace (with men opting for an average temperature of 22°C while women choose 23°C). The study also states that the thermal design of buildings is a function of metabolic rate and clothing insulation, with the metabolic rate usually being the metabolic rate of an active young man. The results of the study show that the building design should take into account the gender and age of its occupants as the metabolic rates of women and senior citizens can vary greatly from the metabolic of a normal, healthy, active male.
The conclusions of the report state that an accurate representation of the thermal demand of all occupants leads to actual energy consumption predictions and real energy savings of buildings that are designed and operated by the buildings services community. The report also states that occupant behaviour contributes to 80% of the variation in energy consumption, so if designers used more accurate metabolic rates in their initial thermal comfort calculations, the behaviour of the occupants could more easily be predicted, once more leading to more accurate energy consumption predictions and greater energy savings.