Case Study - Extension

The project

Our client wished to add an extension to the rear of their property, however there was a significant amount of glazing in the current design in order to reduce energy bills.

What we did

As the existing dwelling was built in the late 1960’s, we assessed the impact of three potential changes on the existing dwelling’s SAP score:

  • Cavity walls injection filled with insulation.
  • Add to the current insulation in the loft approx 100mm with another 200mm mineral wool cross laid to meet current requirements.
  • Replace the gas boiler, which was over 20 years old, along with the hot water cylinder.


The final enlarged dwelling had the extension as designed, with some minor adjustments to the fabric where necessary to meet the requirements, and the customer decided they would implement all three changes to the existing dwelling.

The extension calculations produced showed that incorporating these changes meant that the CO2 emissions of the dwelling reduced by a third.

Elmhurst Energy Services Ltd. 16, St Johns Business Park, Lutterworth, Leicestershire, LE17 4HB

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