What is a 'Passivhaus' building?
'Passivhaus', or "passive house in English", is an international building standard for energy efficiency that results in ultra low energy buildings requiring very little heating or cooling.
It is achieved through a combination of super insulation, airtight construction, high-performance triple-glazed windows, elimination of thermal bridges, and a mechanical ventilation with heat recovery (MVHR) system to maintain fresh air quality. This "fabric first" approach dramatically reduces the need for conventional heating and cooling, leading to significant energy savings and increased comfort.
Key principles and characteristics
Super insulation:
Thick layers of insulation are used in the walls, roof, and floor to minimise heat loss in the winter and heat gain in the summer.
Airtight construction:
The building is sealed to prevent drafts and unwanted air leakage, which is critical for maintaining a consistent temperature.
High-performance windows:
Triple-glazed windows with low-emissivity glass are used to prevent heat from escaping. Windows are also strategically placed to maximise passive solar gains in the winter.
Elimination of thermal bridges:
The design ensures that there are no weak points in the building's thermal envelope where heat can easily escape.
Mechanical ventilation with heat recovery (MVHR):
An MVHR system continuously supplies fresh, filtered air to the building while recovering heat from the outgoing stale air to pre-warm the incoming air. This ensures excellent indoor air quality, without creating drafts.
Passive and internal heat sources:
Buildings are designed to make efficient use of the sun's heat, lighting, and internal heat generated by occupants, reducing the need for active heating.
Benefits of a Passivhaus building
Energy savings
Passivhaus buildings can use up to 90% less energy for space heating and cooling compared to conventional buildings.
Increased comfort
Occupants experience a consistent, comfortable indoor temperature year-round, with no drafts.
Superior air quality
The MVHR system provides constant fresh, filtered air, which is beneficial for occupants with allergies or asthma.
Quieter interiors
The airtight and well-insulated nature of the buildings results in reduced noise from outside.
Reduced carbon footprint
The focus on energy efficiency leads to a substantially reduced carbon footprint for the building.
