Cramer,
ASHRAE's GRP 158 Cooling and Heating Load Calculation Manual indicates heat gain from a child is taken as 75% of adult male, see attached.
Mark

In the Ashrae fundamentals handbook there is a table of heat gains from
people at different activity levels in the non residential heating and
cooling loads chapter( Chapter 18 of the 2009 version). Children should be
calculated at 75% of the adult male heat gain value per that table, it has
been in the ASHRAE handbook for years.

Cramer, from my old days of studying thermal comfort I seem to remember
a correlation between heat output and body area. I seem to remember that
average adults have a body area of 1.68m2 that produce 70W of sensible
heat. So if the body area of a child is less than the 1.68m2 then the
heat output can be reduced proportionally. I think this is report in
Thermal Comfort by Fanger, 1972

It seems to me that correlating a child's body area with heat loss as a
direct ratio of an adults heat loss would not account for the significantly
higher metabolic rate that children have. Remember there are various heat
loss values published for adults depending on their activity level.

Agreed, but the metabolic rate can be adjusted in proportion to the body
area. If you use the new ASHRAE 55 thermal comfort you can run all the
different metabolic scenarios and adjust these for different body areas.

Cramer,

ASHRAE's GRP 158 Cooling and Heating Load Calculation Manual indicates heat gain from a child is taken as 75% of adult male, see attached.

Mark

In the Ashrae fundamentals handbook there is a table of heat gains from

people at different activity levels in the non residential heating and

cooling loads chapter( Chapter 18 of the 2009 version). Children should be

calculated at 75% of the adult male heat gain value per that table, it has

been in the ASHRAE handbook for years.

cid:image003.png at 01C9AB43.F0BEE290

Robert Gengelbach, PE, LEEDR AP BD+C

Cramer, from my old days of studying thermal comfort I seem to remember

a correlation between heat output and body area. I seem to remember that

average adults have a body area of 1.68m2 that produce 70W of sensible

heat. So if the body area of a child is less than the 1.68m2 then the

heat output can be reduced proportionally. I think this is report in

Thermal Comfort by Fanger, 1972

Peter Simmonds, Ph.D.

It seems to me that correlating a child's body area with heat loss as a

direct ratio of an adults heat loss would not account for the significantly

higher metabolic rate that children have. Remember there are various heat

loss values published for adults depending on their activity level.

cid:image003.png at 01C9AB43.F0BEE290

Robert Gengelbach, PE, LEEDR AP BD+C

Agreed, but the metabolic rate can be adjusted in proportion to the body

area. If you use the new ASHRAE 55 thermal comfort you can run all the

different metabolic scenarios and adjust these for different body areas.

Peter Simmonds, Ph.D.

A 5' 8" tall 154 lb male surface area is 19.6 s.f. (Du Bois) and

produces about 400 Btu/hr (117 W) at seated at rest.

Maybe you can do the math

Nader V. Chalfoun, Ph.D., LEED AP, CEA