Low-Energy Houses and Passive Houses
Particularly energy-efficient buildings offer economic benefits in the face of rising energy prices, help combat climate change and provide a very pleasant room temperature.
In Germany, buildings that meet the low-energy house standard have an annual energy requirement of between 30 and 70 kilowatt hours per square metre. The term "passive house", meanwhile, refers to particularly efficient buildings that do not require an active heating system to achieve a comfortable room temperature. To meet this standard, the annual energy requirement per square metre for room heating must be reduced to less than 15 kilowatt hours, while the building must also be equipped with ultra-efficient ventilation and heat recovery systems.
To achieve these values, renovation of the building envelope and the heating and ventilation systems must be planned and executed by professional experts. Energy-efficient optimisation of the building envelope includes doors and windows, as well as insulation of the exterior walls and basement, roof, roofspace and floor slab. Thermal bridges, in particular around windows and in entrance areas, are to be avoided as far as possible. Savings can be made in the building's HVACR (heating, ventilation, air conditioning and refrigeration) through efficient heat generation and distribution, a large proportion of passive solar energy utilisation and sophisticated ventilation technology.
The "Energy-Optimised Construction" (EnOB) programme of the Federal Ministry of Economics and Technology and the "Low Energy Standards for Existing Buildings" project of the German Energy Agency (dena) provide impressive demonstrations of how, through best practices in energy-efficient renovation, existing buildings can meet the same standards as a low-energy house (see www.enob.info).