Passive House Design

Passive Houses are well sealed. The building envelope creates a solid barrier with no air leaks, providing full control over the internal environment and significantly improving thermal comfort, (windows can still be opened though).

The entirety of the building must be sufficiently insulated to minimise heat loss or gain. This requirement helps to maintain a consistently comfortable indoor temperature and reduces the risk of condensation.

An airtight building needs a  reliable source of fresh air for both human comfort and building longevity.

Good ventilation is essential as it prevents the accumulation of harmful contaminants, such as carbon dioxide, volatile organic compounds (VOCs), and excess moisture, which can lead to mould growth.

In traditional buildings, fresh air enters via vents and through infiltration or draughts. This system is uncontrolled and cannot guarantee uniform ventilation throughout the building.

In a Passive House, various approaches, including Mechanical Ventilation Heat Recovery (MVHR), Heat Recovery Ventilation (HRV), and Heat Ventilation and Air Conditioning (HVAC), use thermal energy within the building to pre-heat or pre-cool (depending on the season) incoming fresh air, ensuring clean, filtered air is provided regardless of outdoor conditions.

Windows in a Passive House must be well insulated with low-emissivity double or triple glazing. Only thermally broken or non-metal frames can be used.

High-performance windows are crucial as they are the key element in controlling heat flow into and out of the building. Windows must also be appropriately shaded.

Thermal bridges are weak points in the building envelope where heat transfers in and out.

They reduce your home's energy efficiency, leaving it cold and damp in winter and too hot and humid in summer.

More critically, they create the conditions for condensation to form, potentially leading to mould and moisture-related structural damage.

Thermal bridge-free construction results in a healthier, more comfortable home with lower energy costs and greater structural durability.

To achieve this standard, insulation must be continuous to keep thermal penetration to an absolute minimum.

Where it is unavoidable, as in the case of windows and doorways, thermal bridges can be eliminated by incorporating thermal breaks or using materials that are poor heat conductors (eg. timber instead of metal).