Specification for a Passive House

One of the key features is the use of available energy; i.e. the basic principles are the minimising of heat loss and maximising of heat gain. To qualify for the passive house building standard, it is not enough merely to put together passive house-appropriate components; the whole is more than the sum of its parts. Because of the interaction of individual components, integrated planning is essential so that the completed building fulfills three following requirements:

• Heating output requirement < 15 kWh/m²a
• Primary energy requirement (heating/hot water/household appliances) < 120 kWh/m²a
• Pressure test air change n50 < 0,6 h-1, i.e. in a pressure differential of 50 Pascal, the air current must come to less than 60% per hourof the volume of the building .

Raising the comfort factor

Because of effective insulation heat stays within the building, and all surrounding areas are equally warm. Consequently there is no radiation assymetry (heat-loss radiation) through the outside walls of a passive house, nor any resulting draughts. Conversely, the heat in summer stays outside and this prevents overheating inside. Because of these factors the room temperature in a passive house remains constant and comfortable throughout the year, ensuring a high standard of comfort and cosiness for the occupier. In addition, passive houses have super-efficient ventilation systems which prevent a build-up of mould and dust and their resultant allergies.

Cost-effectiveness and environmental protection

The CO2 emissions and heating costs of a passive house can be vastly reduced, because energy consumption is lowered by up to 90%. Compared with a conventionally-built house, the passive house saves on average 4,000 kg. per year of greenhouse gas (carbon dioxide)emissions. That equates roughly to a 27,000 km. journey in a 6 litre car. As a further illustration: the daily heating load in a passive house is 10 W/m². 300 watts are required for a room of 30 m², roughly equivalent to the heat generated by 10 tea-lights. Effectively, a living area of 30 m² can be heated with only 10 tea-lights as opposed to the almost 100 tea-lights which would be needed to heat a similar area in an older building.