Passive energy building provides an opportunity for designer since both the design and the building materials can be freely chosen. Although the orientation of buildings towards the south produces energy benefits, experience proves that the concept is also functional on building sites facing north. The heating energy need is affected by the shape of the building; simple square and cube shaped buildings are the most efficient.
Observing the cooling need in architectural design
The reduction of the heating need using passive solar heating depends on the direction of the house and windows. The cooling need early in the spring may constitute a problem. Large windows facing south may be part of habitability but they require sufficient solutions for controlling the indoor temperature and preventing overheating. Balconies, wide cornices, canopies and shades outside the house are efficient means of fighting against solar heat in the summer.
Envelope: Designing thermal performance
When you design a low- or passive-energy building, you must recognise that all aspects of the building are inter-related:
- the building envelope (heat, air and moisture movement)
- the mechanical systems (HVAC)
- the inhabitants
Understanding the relationship between these three factors is critical for a successful design. For instance, higher insulation levels mean that the house will require a smaller heating system, and a more airtight house requires mechanical ventilation.
In the design of thermal performance of the building envelope, three main factors must be considered:
- Thermal transmittance including windows and doors
- Airtightness against infiltration
- Wind protection against the intrusion of cold air