adpractice Ltd Hertfordshire architects
What is Passivhaus?
Passivhaus explained in 90 Seconds
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 (Passivhaus Trust).
The basic principle of a Passivhaus is to reduce the heat losses of a building to the point that it hardly needs any heating at all. The sun, occupants, household applicants and the warmth from extracted air cover most of the heating demand. The standard relies on good levels of insulation with minimal thermal bridges and well-designed uses of solar and internal gains.
The buildings are made as airtight as possible which results in the installation of mechanical ventilation heat recovery (MVHR) systems which provide excellent air quality and heat recovery efficiencies in excess of 80%. All of this means that a traditional heating system is no longer required and the shortfall can be covered with a small unit, such as a wood burning stove.
Despite the name, its not just houses that can be Passivhaus certified, there are a growing number of non-domestic Passivhaus buildings in the UK, particularly schools.
Passivhaus certification is also possible for very low energy retrofit projects. EnerPHit is a slightly relaxed standard for retrofit projects, where the existing architecture and conservation issues mean that meeting the Passivhaus standard is not feasible.
Passivhaus Benefits
Building Performance
What Passivhaus achieves in terms of a building’s energy demand, performance gap, comfort & quality.
• Low energy demand
• Reduces performance gap
• High levels of comfort
• Effective and healthy ventilation
• Higher performance building components
• Better site QA procedures resulting in better construction quality
• Lower risk of building fabric damage
• Resilient and future-proofed building
Climate Emergency
Decarbonisation is acritical part of our journey to net zero. Passivhaus enables the levels of demand reduction that we will need to achieve net zero.
• Lower carbon emissions
• Lowers peak demand
• Lowers the overall requirement for renewables
• More economical to save energy than to generate it
• Gives us the best chance of achieving net zero in buildings
• Enables decarbonisation without increasing fuel bills
• Robust in the face of short-term extremes and longer-term climate changes
• Ability to support demand response
• Lower cooling requirement in a future warmer climate
Health and Wellbeing
Decarbonisation is acritical part of our journey to net zero. Passivhaus enables the levels of demand reduction that we will need to achieve net zero.
• Eliminates cold homes & associated health impacts
• Guarantees good levels of ventilation
• Reduces internal pollutants such as VOCs
• Deals with internal humidity – eliminates condensation and mould
• Improves quality of life for people with chronic illness or disabilities
• Protects against external air pollutants
• Reduces risk of airborne infection
• Reduces the impact of external noise
• Reduces risk of buildings becoming too hot in
summer
• Improves health of people in schools & office
People On Performance
The improved living and working environments offered by Passivhaus can improve productivity, learning outcomes and reduce absenteeism.
• Reduced absenteeism
• Improved productivity
• Improved learning out comes
• Attract and retain staff
Financial
Affordable to run, Passivhaus can also offer lower maintenance costs, reduce fuel poverty, and open access to green finance or better rates on mortgages.
• Low energy bills
• Fewer & shorter rental void periods
• Reduces extent & depth of fuel poverty
• Higher capital value 5-7%
• Lower maintenance & management costs
• Access cheaper time of day tariffs
• Lower whole life costs
• Lower borrowing costs. Green mortgages
• Ability to access cheaper green finance
• Holds value in the event of future carbon or efficiency legislation
• Lower risk of defects litigation
• Lower risk of repetition on al damage due to quality issue
Social
Improved well being and productivity reduce the load on health & social care and provides better life chances. These are potentially far-reaching benefits. Often difficult to quantify - they cannot be ignored.
• Improved health & wellbeing of communities
• Reduced demand on health and social services
• Improved learning out comes for children
• Economic stimulus of construction
• Upskilling of the construction workforce
• Clear statement of intent for transition to a net zero economy
• Demonstrates compliance with social value policies & targets
• Aligns with several UN Sustainable Development Goals
Why Choose 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%. (Passivhaus Trust).