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Insulate the roof first for energy efficiency: here's how and why

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Matt Loader

Start at the top for an energy efficient building, says Matt Loader, with a breakdown of two of Loader Monteith's projects

Making an energy efficient building, is, at its heart, a fairly simple affair. Insulate the envelope well to minimise heat loss, cut openings, add site-specific technology to provide heating and power. Of course, as you get into the detail it becomes more complex, but this is the driving principle of making a building which is comfortable to live in and affordable to heat.

Since heat rises, a roof that works really hard will have a more positive impact than heavily insulated walls and floor; a roof light with a U-value of 0.7W/m²K is roughly equivalent to a window the same size of 1.2W/m²K. Having a constant line of insulation that is not disrupted by the structure is a fundamental principle we apply to all of our projects.

We’ve shown two drawings which focus on the roof – one for our newbuild Manser Medal shortlisted Ceangal House in South Lanarkshire, the other for our retrofit of the category A-listed house High Sunderland in the Scottish Borders.

  • Credit: Dapple Photography
  • Credit: Dapple Photography
  • Credit: Dapple Photography

While we have the above guiding principles underpinning both details, we’re always keen to ensure the desire to make a warm envelope doesn’t compromise the quality of the space inside or out. At High Sunderland, we had to respect the eaves line, which was critical to the house’s external character, while the timber ceiling was absolutely essential inside. For this reason, as we turned the house into a ‘warm roof’ we came up with the stepping profile. This took the U-value of the roof from 0.2 W/m²K to 0.16 W/m²K.

At Ceangal House, we wanted to expose the roof structure to provide a warmth and texture to the living spaces, and although it was a pitched roof, we also used a warm roof. This decision to wrap the structure in a thick line of insulation with no penetration of the primary structure allowed us the autonomy to expose the structure, and control the internal look and feel. 


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