Gender and muscularity decisive – women feel the cold more than men
Because people in developed countries spend about 90% of their time indoors,
their sense of warmth becomes one key comfort factor for interior spaces. VTT
Technical Research Centre of Finland has developed a new method for assessing
the individual thermal comfort experienced by different user groups. The
design of energy efficient buildings – such as day care centres, schools,
offices and homes for the elderly – should pay more attention in future to the
thermal comfort of user groups according to real needs.
The new method developed for assessing thermal comfort (Human Thermal Model,
HTM) is based on modelling of individual anatomy and physiology. The method
can be used to assess the impact of individual characteristics – gender, age,
body mass index and muscularity – on the volumes of various tissue types
(bone, muscle, fat and skin).
The heat and moisture transfer between a person's anatomy, clothing and the
environment determine the local temperature of body tissues. These temperature
values can be used to calculate the local thermal comfort of different parts
of the body.
An adequately precise identification of the various body tissues is important
because muscle tissue, for example, when at rest produces heat at a basal
metabolic rate of 0.67 W/kg, while the heat produced by fat tissue is at a
rate of 0.004 W/kg. Light office work produces just over 2W of thermal power
per kilo of muscle, while cleaning work produces 5W and strenuous sporting
performance momentarily over 20W.
When comparing the thermal comfort of women and men using same values for all
other individual characteristics (body mass and muscle indexes), the indexes
for male thermal comfort were on average 0.39 units higher than for women in
the case of 20-year-olds and 80-year-olds, and 0.48 units higher for
Several previous researches have shown men to have statistically more muscle
tissue on average than women. People also lose muscle mass as they grow older.
Because the thermal output of muscle tissue per kilogram is several orders of
magnitude higher than that of fat tissue, it is important to be aware about
individual amount of muscle tissue. Thus gender and individual muscularity in
particular out of the various characteristics have a considerable impact on
metabolic rate and tissue temperature – and in the end on the person's thermal
One mega trend in the coming years will be continuous improvement in the
energy efficiency of existing and new construction. From occupant point of
view it will important to be able to estimate thermal comfort of different end
user groups, so that relevant design and maintenance solutions would ensure
simultaneous fulfilment of both energy efficiency and satisfaction with
The impact of individual human characteristics on thermal comfort will be
presented in June at the Building Simulation and Optimisation 2014 conference
in London, as well as at other venues.