Low-energy houses
Low-energy houses refer to a building that uses a lower amount of energy than what today’s building code requires (BBR for the Swedish market). The interest in building a low-energy house is increasing.
Passive house Classic
Passive houses are buildings that are “passively” heated by the sun, internal heat gains and the heat recovered from the ventilation system. This causes heat energy savings of up to 75% compared to buildings that meet the upcoming requirements.
This is achieved by the two basic principles of the passive house:
- Minimize heat losses
- Optimize heat gains
The passive houses are divided into 3 classes:
Classic, Plus & Premium.
Criteria for Passive House Classic:
- Specific annual heating requirement of max. 15 kWh/m2year or maximum heating power requirement of 10 W/m2.
- Air exchange at test pressure n50 maximum 0.6 air-turnovers/h.
- Consumption of renewable primary energy a maximum of 60 kWh/m2year
- Production of renewable primary energy 0 kWh/m2year
With a well-insulated building envelope, triple glazing windows with insulating frames and unbroken airtightness layers you can ensure that the heat stays in the house. A passive house also receives heat gains through solar radiation, individual heating from inhibitants and domestic appliances.
A passive house gets its supply air from a HRV system with high recovery. The heat exchanger recovers at least 75% of the heat from the extract air and transfers it to the fresh outdoor air which gives a very low need for additional heating.
In Germany thousands of passive houses have been built. In Sweden, the most famous example is the so-called Lindås houses south of Gothenburg. These townhouses just have a small additional heat source for heating. The installed power is less than 10W/m2.
To cope with heating using passive heat sources it is necessary to minimize all heat losses from the house. The Lindås houses minimizes heat leakage through an especially well-insulated building construction. Windows and doors are also using maximum insulation and finally almost all the heat in the efficient ventilation system is recovered.
Passive house Premium & Plus
The passive house classes Plus & Premium are based on the house producing its own primary energy, for example, using solar cells.
Criteria for Passive House Plus:
- Specific annual heating requirement of max. 15 kWh/m2year or maximum heating power requirement of 10 W/m2.
- Air exchange at test pressure n50 maximum 0.6 air-turnovers/h.
- Consumption of renewable primary energy a maximum of 45 kWh/m2year
- Production of renewable primary energy 60 kWh/m2year
Criteria for Passive House Premium:
- Specific annual heating requirement of max. 15 kWh/m2year or maximum heating power requirement of 10 W/m2.
- Air exchange at test pressure n50 maximum 0.6 oms/h.
- Consumption of renewable primary energy a maximum of 30 kWh/m2year
- Production of renewable primary energy 120 kWh/m2year
For more information about passive houses: www.igpassivhus.se