The biggest energy hogs in a home are an antiquated heating system and heat losses through windows, roof, basement and (the largest interface to the outside) the outside walls. Their design and composition is significant for energy consumption (heating requirement).

Ever more, energy consumption is a determinant of the value of your property. Since 2008 the Energy Performance Certificate has been required for new construction; this certifies the energy consumption (energy index) of your house. This value in turn decides the amount of subsidy to which you are entitled.

Do not forget:

• Check your local and regional construction code. Some set minimum requirements for each heat conducting construction component.
• Building materials are labeled with a U-value (measure of heat loss of components). This simplifies a comparison: the lower the value, the less energy loss.
• Example: Subsidies for private homes in Upper Austria are now available only up to an effective heating energy index of at most 50 kWh/m²a. Your selection of building materials is significant for such subsidies.
• Bays and other projections increase energy consumption.
• In addition to thermal insulation, air-tightness is also important, because if the wind blows the warm air outside next to the thermal insulation, then even the best insulation cannot help.

Conventional building shells

• Single-layer facade: based on today’s standard, highly insulating building stones with a wall thickness up to 50 cm, no additional insulation layer required. Otherwise the economically optimal insulation thickness is currently about 16 cm. Depending on wall thickness, this achieves thermal insulation (U-value from 0.20 W/m²K) for construction to the low-energy house standard.
• Single-layer masonry with façade insulation such as heavy-duty thermal insulation or mounted facade. Depending on insulation thickness, this yields insulation values that meet the passive house standard (U-values under 0.15 W/m²K). 
• Wood frame construction (especially prefabricated homes): 20 cm insulation between the studs as well as inside and outside lining deliver good insulation values. Ensure wind-tightness and vapor barrier. Compared to wood block homes (log cabins), this prefabricated construction form has the advantage of less wood required and better thermal insulation options.
• For both new construction and renovation, a suitable option is ventilated facades, which provide less condensation and comfortable room climate.

Caution on renovation

If you consider that up to 75% of the heat in an unrenovated house escapes via outside walls, then retrofit insulation certainly makes sense and saves enormous energy costs. Heavy-duty thermal insulation comes to the rescue.

In principle it is also possible to retrofit inside insulation. This absolutely requires a vapor barrier on the inside of the insulation to avoid the danger of condensation and mold in corners and at thermal bridges.

In general, to optimize the success of renovation, we suggest thermographic imaging. A special infrared camera measures the thermal quality of the building shell and detects its weaknesses. this enables targeted renovation.