New build: near Ilminster, Somerset — completed 2015

Originally planned as an extension, the decision was made to demolish the existing dwelling and start fresh — giving a clean opportunity to build the fabric, airtightness and MVHR in from the ground up rather than work around an existing structure.

As-built results:

• Airtightness: 0.80 m³/h.m² @ 50Pa — 2.5x tighter than the design target, ATTMA certified

• EPC rating: A (94) — a rating very few UK homes achieve

• Primary energy use: 14 kWh/m² per year

• CO2 emissions: ~0.4 tonnes/year (national average: 6 tonnes)

• Dual air source heat pump system with solar PV and wood-burner backup