Condensing boilers: still the most cost-effective technology for domestic space heating and hot water By Jean Schweitzer
Sixty million gas boilers are installed in the
high lifetime are making the technology even
EU and represent one of the major space
more attractive.
heating technologies. Studies have shown that once users are confronted with a situation
Is the gas boiler a technology of the past?
where they need to replace their boilers, the
Not at all, on the contrary the replacement of
majority of them would prefer to invest in a
old gas boilers by condensing boilers can bring
gas boiler again.
cost-effective energy savings and CO2 reduc
Is this a good option? Knowing that
tions. Furthermore, the gas boiler combined
“decarbonisation” of space heating is becoming
with a small electrical heat pump (EHP) will
part of the EU heating strategy, this question
help a smooth “decarbonisation” of space
is relevant.
heating for the benefit of the end user and
However, the EU electrification of space
the society.
heating with electrical heat pumps is proving to be more difficult than planned: Prices of appli
Introduction
ances are high and the extensive electrification
In the context of the energy transition dis
of heating will require costly power infrastruc
cussion, gas boilers are often considered a
ture investments (production and distribution).
technology of the past that should be replaced
In this context, the gas boiler still has an
by highly-efficient new technologies. However,
important role to play.
the condensing boiler is still the most cost-
This paper presents in detail the
effective solution to space heating and offers a
performances of gas boilers so the technology
smart road to energy transition when coupled
can be fairly assessed in comparison with other
to a small EHP (hybrid technology).
space heating technologies. Detailed data measured over the last 25
Due to the high costs of competing tech nologies (heat pumps, micro-CHP etc.), the
years by the Danish Gas Technology Centre
consumer’s first choice is still the gas boiler.
(DGC) on about 200 boilers give a rather
At the same time, hybrid solutions and the
accurate picture of the performances of gas
development of green gases have contributed
boilers for efficiency, emissions and electricity
to making the gas boiler an interesting option
consumption. The data of the investigations are
for preparing the energy transition, and
valid for many of the EU countries as the
decision makers’ opinions on gas boilers have
appliances are the same.
recently started to change.
When combining the performances with
The heating market, however, is entering
the appliance and maintenance cost in
into tough battles and figures used to calculate
Denmark, it appears that the condensing boiler
performances of heating systems are being
is still the most cost-effective technology for
discussed and challenged by the different
space heating. The present low gas cost and
stakeholders involved. This has given rise to
68 C o n d e n s i n g b o i l e r s : s t i l l t h e m o s t c o s t - e f f e c t i v e t e c h n o l o g y f o r d o m e s t i c s p a c e h e a t i n g a n d h o t w a t e r
