Energy Efficient Wooden Door

A client wanted an energy efficient wooden door for his Victorian property.  But he was unable to find a suitable U-rated hardwood door so he approached us to make an insulated back door.

Improving Property Energy Rating

Like many landlords, our client faced the headache of trying to improve the energy rating of his rental property.  He planned a series of upgrades to raise the EPC rating of his Victorian terraced house in Cherry Orchard from a band D to C band, to comply with the proposed rules changes. This included replacing the single glazed softwood backdoor for a wooden energy efficient hardwood door.

Low U-Rating of Wooden Doors

After an extensive online search, however, he couldn’t find a hardwood door in a particular style that had a good u-rating – he only found softwood doors or uPVC doors. According to Part L of the building regulations (p.25), the thermal efficiency of a door in an existing dwelling needs to have a minimum U-value of 1.8W/(㎡K). (Note this value will decrease to 1.4 from June 2023 and the lower the rating, the higher the energy performance). He wanted a comparable energy efficient rating. Regular hardwood doors have a U-rating of around 3.

Energy Efficient Door Design

The client’s solution was to design a hard wooden door with a thermal lining. The thermal lining that he chose had a U-rating of 1.497. The double glazing had an energy efficiency rating of 1.2. We are not qualified to energy rate our doors. He was advised that he didn’t need to comply with building energy regulations as he only replaced the leaf of the door and not the frame. But this data could be provided to an EPC assessor as evidence of its energy efficiency. 

Constructing An Energy Efficient Wood Door

We made the energy efficient paneled door in our workshop from Sapele, a hardwood.  We used mortice-and-tenon joints and constructed a wooden frame to the back of the door. We fixed the reflective thermal lining inside the frame.  We covered the lining with a wooden ply and painted the door leaf. It was then fitted to the old door frame with new draft proof strips.  Upon completion, we issued a certificate stating the u-values of the thermal door lining and double glazing. This will be submitted to an EPC assessor.

This energy efficient wooden door was not our design.  We will need to see what an energy performance assessor makes of the door and about its durability.  But it is an interesting solution to the problem of finding a u-rated hardwood door. It also shows the bespoke work that we can do to improve a property’s energy performance.

Upgrading your doors

If you are looking for energy efficient or u-rated wooden doors, do get in touch to discuss your design and get a free quote. Oliver Gibbs Carpentry and Joinery provides carpentry and joinery services to Shrewsbury and within Shropshire. With energy prices set to continue to increase next year, commissioning energy saving work is increasingly cost effective.

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