Passivhaus


The Passivhaus standards’ strengths lie in the simplicity of its approach; build a house that has an excellent thermal performance, exceptional airtightness with mechanical ventilation! This robust approach to building design allows the designer to minimise the 'Heating Demand' of the building and in some residential buildings only specify a heated towel rail as means of conventional heating, this heat can then be recovered and circulated by a Mechanical Ventilation and Heat Recovery (MVHR) unit. Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. They are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany, and can be certified through an exacting quality assurance process.

Why Passivhaus?

 

Passivhaus buildings achieve a 75% reduction in space heating requirements, compared to standard practice for UK new build. The Passivhaus standard therefore gives a robust method to help the industry achieve the 80% carbon reductions that are set as a legislative target for the UK Government. Passivhaus also applies to retrofit projects, achieving similar savings in space heating requirements.

Evidence and feedback to date shows that Passivhaus buildings are performing to standard, which is crucial, given that the discrepancy between design aspiration and as-built performance for many new buildings in the UK can be as much as 50-100%

 

How to achieve the Passivhaus Standard in the UK To achieve the Passivhaus Standard in the UK typically involves:

 

  • very high levels of insulation

  • extremely high performance windows with insulated frames

  • airtight building fabric 

  • 'thermal bridge free' construction

  • a mechanical ventilation system with highly efficient heat recovery

  • accurate design using the Passive House Planning Package (PHPP)

“The heat losses of the building are reduced so much that it hardly needs any heating at all. Passive heat sources like the sun, human occupants, household appliances and the heat from the extract air cover a large part of the heating demand. The remaining heat can be provided by the supply air if the maximum heating load is less than 10W per square metre of living space. If such supply-air heating suffices as the only heat source, we call the building a Passive House”

 
Univ. Prof. Dr Wolfgang Feist Head of Energy Efficient Construction/ Building Physics at the University of Innsbruck, Austria and Director of the Passive House Institute, Darmstadt, Germany.