For Kindle readers, check out final gallery from the e-book Why Most People Don't Build Energy-Efficient Homes.
These photos show some successful UK retrofit projects.
Grove Cottage, Simmonds Mills. Externally insulated, this project is certified to EnerPHit standard.
Lena Gardens, Green Tomato Energy. This house has been certified to Passivhaus standard.
Totnes Passivhaus, Passivhaus Homes. This award-winning project was a full Passivhaus retrofit.
Princedale Road, Paul Davis + Partners and Octavia Housing. Internally insulated, this is also certified to Passivhaus standard.