Clients Peter and Penny were looking to build a home to retire to in Wales and were keen to keep energy bills to a minimum. While exploring the selfbuild option they discovered the Passivhaus low energy standard, which appealed because of its fabric first approach to energy efficiency. After failing to find a suitable plot of land in an area that they wanted to live in, they started to look for an existing house which they could refurbish using Passivhaus principles. They eventually found Rectory Cottage which fitted the bill as it seemed suitable with a rectangular form, large roof overhang and external cement render making external wall insulation easier.
The project has recently been certified to the EnerPHit standard (via the component route) and has a predicted space heating requirement of 25 kWh/m2/year. Green Building Store windows, doors, MVHR and airtightness products were specified for the Passivhaus retrofit project
EnerPHit – Passivhaus retrofit
Rectory Cottage originally comprised a stone-built cottage, with 18 inch thick walls, which had been extended using block-work cavity construction in the 1960s. The house also needed extensive re-modelling to make more effective use of internal space.
The initial refurbishment design was by Patrick Thomas and the PH details were developed by architect Simon Brown with consultant Alan Clarke and the building work was undertaken by Craig Morgan with Peter effectively acting as Project Manager. As the house is off mains gas it is being heated using LPG gas cylinders using a heating strategy developed by Alan Clarke. The retrofit strategy involved digging out the floors and installing 150mm insulation. This was a major undertaking as the floors had to be hand dug out with spades, pick-axes and wheelbarrows, undertaken by Peter’s cheerful and uncomplaining building contractor, an ex-miner. 200mm of external insulation was applied to the walls with a K-Rend outer finish. The roof was removed and reconstructed to incorporate the airtightness barrier and insulation, thereby providing a warm loft space.
Before construction started Peter attended the Construction Module of the AECB Passive House Designer Course which was delivered by Bill Butcher (of the Green Building Store) and Mark Siddall.
Triple glazed timber windows & doors
Green Building Store’s ULTRA triple glazed timber windows and PERFORMANCE doors (with insulated frame) were key components of the project.
Peter commented: “Green Building Store’s ULTRA insulated frame range was recommended to us as meeting the requirements for the EnerPHit component route. We are really pleased with the windows and doors, which have been crucial in achieving EnerPHit certification.”
MVHR mechanical ventilation with heat recovery
Alan Clarke also designed the MVHR system for the home, using the PAUL Novus 300 MVHR system and rigid steel ducting from Green Building Store. Installing the ducting system has been unproblematic, due to being able to be housed in the space created by the warm roof.
Peter added: “The MVHR system seems to be working really well, is quiet in operation, helping dry out the building and delivering great air quality. It was also good to get practical advice in using the system from Green Building Store’s Steve Clarke, when he came to commission the system”.
Pro Clima airtightness products
Green Building Store also supplied Pro Clima airtightness tapes and membranes for the project. Peter added: “It was great to be able to phone Green Building Store from up on the scaffolding to order extra airtightness products and for them to arrive the next morning.”
Green Building Store
Overall Peter commented on Green Building Store’s service: “We found everyone at Green Building Store to be very helpful throughout the project. They gave great advice and support, which was invaluable to novice self-builders like ourselves.”