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SIGNIFICANT PROOF | 4
Professor
Jarek Kurnitski:
Thermal mass and
energy efficient
heating
In case of
fast-reacting
radiator heating
systems with small
thermal mass, heat
gains elevate room
temperature not
more than 0.5 ° C
The research of Professor Jarek Kurnitski shows that the
thermal mass of heat emitters has a huge influence on
heating system performance. Even during the coldest
Winter period, rapidly changing heat output is needed to
keep room temperature in the optimal comfort range.
The principle of the room temperature response to heat
gains and losses is shown in Fig.4.1, where two systems
are compared. In the case of fast-reacting radiator heating
systems with small thermal mass, the heat gains elevate
room temperature not more than 0.5˚C, keeping room
temperature close to the setpoint of 21˚C. Traditional
underfloor heating with high thermal mass fails to keep
room temperature constant. Research showed that the
setpoint had to be increased to 21.5˚C to keep the room
temperature above the lower comfort limit of 21°C. The
sheer size of the heat emitter meant its output was lagging
behind the heat demand, resulting in strongly fluctuating
room temperature and wasted energy.
Fig. 4.1.
Room temperature
response to
thermal mass of
the heat emitter in
the Winter season
when heat gains
typically do not
exceed 1/3 of the
heating demand
Room temperature
o C
22.5
22.0
21.5
21.0
UFH
Radiator
Set point
UFH
Set point
radiator
Lowest
comfort limit
20.5
0 6 12 18 24 30 36 42 48
Hours
62
63