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Low energy retrofit, Dumfries & Galloway

A low energy retrofit has been undertaken on a Victorian property in Dumfries & Galloway. The house is in the traditional vernacular cottage style of the area and built from local sandstone and is divided into two flats with the upper flat, the subject of the case study, visible from the road. The retrofit has been project-managed by the clients, with building work undertaken by personnel from Nithsdale Stove Centre and Alan and Scott Nicholson, joiners, Lockerbie.

21°supplied the PERFORMANCE triple glazed timber windows and doors for the project, which were finished in a striking pink colour to complement the pink sandstone


The house has been stripped back to its 500mm stone walls and a 100mm breathable IWI insulation system has been applied. Insulation was also added under the floor. Heating is provided by underfloor heating system with an air source heat pump, which also supplies the hot water for the flat. The retrofit is still ongoing but plans are underway to add loft insulation into the cold roof as well as an MVHR ventilation system.

Triple glazed windows & doors

PERFORMANCE triple glazed timber tilt and turn windows were chosen for the project, with paint finishes in RAL 4009 on the outside and RAL 9016 on the inside. Stone bed connector sills were chosen for the project. One set of PERFORMANCE triple glazed timber double doors with glazing bars, were also selected for the entrance door, finished in  RAL 9016 inside and outside.

The clients chose large picture windows which they felt would suit the house well and were keen to have Tilt & Turn windows because they would be easy to clean from inside, something especially needed due to the lack of all-round external access to the windows.

We originally came to an Open Day and talks at 21°s Huddersfield base. We chose the Performance range because of the care that went into the design of the windows and the attention to detail to maximise their efficiency. We also liked the fact that there was a lot of flexibility in the design of the windows. Everyone at 21° was very helpful during the process. Since the windows have been installed, we have had a lot of positive comments. Even when it is windy outside the weather definitely stays outside and it is an ocean of calm inside. People working on the house have noticed how warm it is inside and the contribution the windows are making to that. We’re very happy with the windows and are pleased with how they look.

The client

Life changing homes