Passive Houses do
not need a completely different construction method. In fact, all
new construction can be realized in Passive House standard as well.
It is a series of small steps, each resulting in a better quality
of one component, which will lead beginning with an average new
construction to a passive house. This will be illustrated using
The Passive House settlement
"Lummerlund" sited at the Kronsberg-site in Hannover has
been an important guiding project in the European demonstration
(fig. 1). These houses are ordinary
row houses with tilted roofs. Extrinsicly they do not differ from
ordinary new construction. But they are passive houses - the differences
are small improvements in the details of the construction: more
insulation, better windows, high
air tightness and a heat recovery
from exhaust air.
Each improvement requires a slightly higher investment: The insulation
more insulation material and workmanship, the windows one more pane
with a low-e coating and an insulated frame, the heat recovery a
duct system and the air tightness a pressurization test. The extra
investment costs were documented in this project; they are given
in fig. 2 and added up step by step in fig.
4. At the end the sum of the extra investment adds up to 8200
These measures result
in a reduced heat requirement, see fig. 3. Step
by step the better efficiency reduces the heat demand. In the end,
the improvements add up to a consumption that is less than one seventh
of the original one. One may follow the improvement of the energy
balance in the animation,
too. All steps do not change the character of the building: It stays
an ordinary single family house. The only thing changed is the requirement
for heating energy, but that is changed manifestly. By the way -
the consumptions measured in the realised settlement very well coincide
with the requirements calculated. The energy savings are actually
The extra costs for better
construction and better HVAC-systems pay off. The investment costs
broken down to "one Kilowatthour" (kWh) energy saved are
shown in fig. 5. For insulation these are between
2,5 and 4,5 Cent each kWh. Already in 2001 the costs of the purchased
heating energy were higher - and nowadays, in 2005, heat from heating
oil costs some 6 Cent each kWh. The heat recovery ammounts to some
5 Cent, the Passivs House windows deliver "Saved Energy"
by 7,5 Cent each kWh - but to realize a Passive House, the windows
are needed, anyhow. All measures together result in 5 Cent/kWh -
and that is definitly lower than the contemporary costs of energy
on the market. These Passive Houses pay off - and so far we did
not take into acount the extra benefits like good indoor air quality
and extraordinary good thermal comfort. The energy sources of the
future will be even more expensive - that holds for wind, solar
and biomass energy. It makes sense, to utilize these renewable sources
- at the other hand, it makes sense to utilize the improved efficiency
as well, like it can be done with Passive Houses.
A comprehensive documentation
is available on the Passive Houses settlement for free download:
Houses Kronsberg ( pdf,
english, 4.5 MB). The project was realized in the frame of CEPHEUS.
The builder was the company Rasch&Partner /faktor
10/ (German link).
.5: The economy of the measures: The
investment costs for each single measure (fig .4) and the energy
saved by the measure (fig. 3) are known, as well as the life cycle.
From this the equivalent costs of a kWh saved energy by each measure
have been calculated (including interest). Passive Houses pay back,
already with contemporary energy prices.
is a link to the basic facts about Passive Houses.
Dr. Wolfgang Feist
© Passive House Institute;
unchanged copy is permitted, please give reference to this page)