Passivhaus retrofit
Refurbishing your home using the Passivhaus approach
For retrofits it is harder to reach the exacting requirements of the Passivhaus standard. The Passivhaus Institut has now offers the EnerPHit standard for refurbishment projects which illustrates that it is still possible to achieve vastly reduced fuel bills and minimal heating demand using the Passivhaus methodology with retrofits.
1. Find an architect or builder with experience of Passivhaus design and construction
If you live in the Huddersfield/ West Yorkshire area you can contact Green Building Company, builders of the Denby Dale Passvhaus. We work closely with Huddersfield architect Derrie O’Sullivan and can offer design, build, training and consultancy services for your project.
The Passivhaus Trust is an invaluable source of information and its members are the leading Passivhaus practitioners in the UK.
2. Get planning permission
Passivhaus retrofit projects will probably need planning permission as they might require external insulation or changes to the roof etc. Your architect can help with this – low energy Passivhaus projects should be looked on favourably by planning departments – especially now that Passivhaus is becoming better known in the UK.
3. Design your retrofit using PHPP software
Even if you aren’t aiming for he EnerPHit/ Passivhaus standard, it is still important that a retrofit project is modelled using Passivhaus Planning Package software (PHPP). PHPP modelling needs to go in tandem with architectural designs as it will allow the architect to see what is and isn’t possible within the parameters of the Passivhaus methodology.
4. Fund your project
The Ecology Building Society offers mortgages at preferential rates for houses built to the Passivhaus standard. www.ecology.co.uk
5. Find Passivhaus products
Passivhaus buildings can be built using many conventional building materials found in any builders’ merchant. For the specialist Passivhaus elements such as windows, MVHR systems (mechanical ventilation with heat recovery ) and airtightness products, 21 Degrees offers a specialist range of Passivhaus products.
6. More information
EnerPHit standard
The EnerPHit Standard has been developed by the Passivhaus Institut for retrofits where the existing architecture and conservation issues mean that meeting the Passivhaus standard is not feasible. EnerPHit recognises the difficulty of achieving a full Passivhaus standard in existing buildings and has slightly relaxed requirements for airtightness and space heating demand.
Key criteria
Space heating demand: 25 kWh/m2/ year
Primary energy demand: 120 kWh/m2/ year
Airtightness n50: 1.0 air changes/ hour
Useful links
Passivhaus Refurb Diaries – Rob Prewett’s renovation of an Edwardian house using the Passivhaus methodology
EnerPHit refurbishment, Hereford – Simmonds Mills architects
West Bridgford Retrofit – homeowners’ blog during refurbishment
Retrofit for the future – low energy building database
Passivhaus Trust – the UK Passive House organisation
EnerPHit criteria – Passivhaus Institut
