The construction of a passive building is to some extent more expensive than the construction of a standard building but in the long term such a building is worth the initial investment because it saves energy from the property’s heating and cooling.
It is believed that passive houses spend around four times less energy than standard houses.
When the costs for designing, building, and installing the specific equipment and the costs for heating, cooling, ventilation and hot water, and electricity in a passive house for a period of 15 years are less then the same costs incurred in a newly-built standard house, the passive house is considered cost effective.
The system for heating and cooling in passive houses is constructed on the basis of air ducts through which fresh air comes in. While passing through the ducts the air is heated or cooled so that it enters the rooms at the desired temperature.
Most often the system that is built is one that supplies fresh air through openings with louvers placed close to the ceiling. The air moves slowly and the fact that the air ducts are placed high means there is no possibility for a draft that could make the inhabitants ill or create any discomfort.
Passive houses and buildings have windows like all standard homes and buildings but it is advisable they be opened only when necessary so that the microclimate in the rooms is not upset. In principle, the cooling and heating system always supplies fresh air which is filtered only to remove the dust and pollen that are part of the environment.
From this point of view passive houses are especially suitable for people with respiratory problems, asthma and allergies. The air in the rooms is cleaner, without dust particles, pollution or pollen.
On very cold days, when one cannot sleep with a window that is even slightly open, the inhabitants of standard homes often wake up with a headache due to the lack of oxygen in the room.
This just shows another of the advantages of the passive homes – during the night there is constant supply of heated fresh air and in the morning the inhabitants wake up rested and refreshed.
The air filters must be changed once a year but this is a simple procedure which the inhabitants can do themselves.
In order for a house or a building to be passive many rules and requirements are observed in its insulation. In practice, all elements of the building are insulated as well as the links between them. The windows must have triple-glass panes as the middle pane is low-emission. The walls, floors and ceilings are also insulated. Most often after the insulation is installed the thickness of the walls reaches and exceeds 30 cm so that the heat transfer standard is reached – less than 0.15 W/m2. The doors are also well insulated and packed from all sides.
With passive houses the annual cost of heating, cooling and ventilation should not exceed in total 15 kWh/sq.m. living area.
On the other hand the cost of the energy used for heating, hot water and electric appliances must not exceed 120 kWh/sq.m. per annum.
Only when all of the abovementioned conditions are met can a house or a building be classified as passive.
