Together with the development of building construction as well as increasing level of human awareness concerning ecology, the regulations defining energy consumption (during building exploitation) were also changing. Nowadays, the building classified as energy-efficient has become a standard.
The building which meets passive regulations is becoming more and more popular solution because it is characterized by lower energy demand than the energy-efficient building and it equals up to 15 kWh/m2/year.
In comparison, the same indicator for an energy-efficient building is up to 70 kWh/m2/year.
Because of using several solutions, energy demand has been minimalized.
So, which factors influence on gaining the passivity of the building?
- A passive building should have simple and compact body of as small A/V shape factor (ratio of external partitions to cubage) as possible. Energy-efficient buildings, in contrast, provide more possibilities while designing.
- South wall of the building should have as many glazed areas as possible in order to gain energy from solar radiation as efficiently as possible. The north wall of the building should not have any glazed areas or they ought to be considerably reduced.
- All external partitions (walls and roof) should be additionally insulated so as the heat transfer coefficient for each partition does not exceed 0,15 kWh/ (m2*K). slab foundation must be additionally insulated as well.
- Elimination or reducing the occurrence of thermal bridges by additional, well-made insulation will also allow to reduce energy demand.
- Window and door frames should be characterized by low heat transfer coefficient, and they should be assembled well.
In passive buildings, using mechanical ventilation with heat recovery is an essential requirement because bigger part of heat, necessary to heat the building, comes from solar radiation and from energy which is given back by devices and building occupants.
Operation of mechanical ventilation with heat recovery allows to regain up to 95 % heat, which comes from exchanged air. Because of lower heat demand, traditional heat sources are not used in passive buildings. Instead of them, devices using renewable energy sources such as heat pumps, photovoltaic panels etc. are applied.