Passive House Insulation - The principle
In low-energy buildings the entire building envelope is
highly insulated. The building envelope consists of all the building elements which separate the inside from the
outside. Its main purpose is to provide for a comfortable indoor climate – irrespective of the outdoor climate
which is determined by the weather.
During cold periods (typically from the middle of October to the end of April in Central Europe)
the temperature inside the building envelope is usually higher than it is outside. As a result, heat is lost
through the envelope and, unless this heat is replaced, the inside of the building cools down adjusting to the
outdoor temperature. The inverse applies for hot climates (or during hot periods) with excessive heat entering the
building through its envelope. Therefore, it makes sense to restrict the heat flow in any building
irrespective of the climate – and this is where thermal protection comes in.
→ Good thermal protection can be achieved for all construction methods and has
already been successfully implemented in solid construction, timber construction, prefabricated building elements,
formwork element technology, steel construction and all types of mixed constructions.
→ A high level of insulation can also be applied to existing buildings at any
given point of time.
An important principle has been derived from experience with new low-energy constructions:
“If you do it, do it right!” - Don’t save on the insulation when it comes to thermal protection
measures. This principle is taken very seriously in Passive Houses – because quality insulation is a very
affordable way of saving energy.
As a matter of fact, it is thermal insulation and not heat storage which is important (see
insulation or storage). A high level of insulation has always proven to be effective; to learn more please go to
the following page: Thermal protection works.
Heat losses through external walls and roofs account for more than 70% of the total heat losses
in existing buildings. Therefore, improving thermal insulation is the most effective way to save energy. At the
same time it will help improve thermal comfort and prevent structural damage (see further
information about thermal insulation). Financial support such as low-interest loans, as currently available
in a number of countries, reduces the initial investment for improved thermal insulation; yet, even without such
incentives, the investment will pay off in the long term, as shown by a careful analysis.