How it functions
The main strategy of a passive building is reusing the “free” energy in order to heat the house.
This “free” energy is produced by all the electrical appliances, like stoves, refridgerators, computers, lamps etc. The building shell of a passive house has to be really well insulated and airtight, so that this “free” energy does not leave the interior of the house unused.
- 1 Thermal insulation
- A correctly insulated shell, during the winter, maintains the heat inside the building, while during the summer it prevents the heat to enter the house.
- 2 Passive House windows
- The correctly designed, insulated and installed frames participate in the best usage of solar gains.
- 3 Ventilation heat recovery
- The ventilation systems of passive buildings offer clean air, free of pollen and dust, with maximum energy efficiency through heat recovery and humidity control.
- 4 Airtightness of the building
- Passive buildings are designed to avoid air leaks in the building shell, thus increasing energy efficiency and preventing the occurrence of drafts and damage from moisture.
- 5 Absence of thermal bridges
- Minimising thermal bridges and weaknesses in the building shell, contributes to creating a pleasant and constant temperature and eliminates damage from moisture while increasing energy efficiency.
Shading, natural night ventilation, air geothermal systems and correct design of thermal mass contribute to better performance of passive buildings in Mediterranean climates.
As a result, we can describe what is happening as follows:
- A mechanical ventilation system with an air to air heat exchanger is installed so that it can simultaneously bring fresh air and remove a corresponding amount of stale air.
- The warm stale air that leaves the house, “carries” the “free” heat, which through the exchanger moves to the fresh air which enters the house.
- The cool external fresh air enters the exchanger, receives the heat of the rejected stale air and enters the house during the winter months, while during the summer the rejected stale air cools the – warmer – incoming fresh air.
- The cost of an expensive conventional heating/cooling system can be avoided and economic benefits can be attributed to better insulation, improved airtightness, window frames, ventilation system and an economic backup heating system.