Last weekend was Open House London, when some of the capital's most fascinating buildings and homes open their doors and invite nosy members of the public like me to have a good sniff around. This year, several eco-dwellings were open to the public, including Donnachadh McCarthy's pretty cottage in Camberwell, the architect Alex Michaelis's stunning underground eco-palace with indoor swimming pool, and Will Anderson's stylish "tree house".
Not knowing whether five or 500 would turn up, Donnachadh asked me and S to help steward on Saturday. To our surprise, the place was heaving with a polite crowd (more Kefalonia than Costa del Sol), many of whom arrived on bikes.
Having spent a happy hour shuffling through the house, they ended up in the garden where Donnachadh held court for hours without even a loo break. (He wouldn't have been able to get into the bathroom anyway as it was crammed with punters examining the low-flush loo (thank heavens it was nailed down!), which uses rainwater from the harvester on the roof.)
Many of the questions were about the wind turbine, which, on that windless day, was motionless. It has turned out to be Donnachadh's least successful eco-buy.
Most UK residents live in old houses and feel this is a hindrance to greening up, but Donnachadh's cottage shows what can be done by super-insulating, and installing solar panels and a wood-burning stove.
But for those fortunate enough to build their house from scratch, the possibilities for green initiatives are limitless. As we discovered when we visited Will Anderson's tree house in Clapham on Sunday.
Readers may have followed Will's progress in this paper as he found a plot of wasteland and transformed it into an oasis of light, glass, wood and water. I felt alternately uplifted and disheartened as we looked around. Will my eco-conversion look this good (or be this tidy)? I confessed to a pang of eco-envy as we shuffled out of paradise on to the street.
My own project is ready to begin now, but I'm in a lather of indecision about who should do the work: Vince, my trusted builder; or S, my long-suffering inamorato who, most conveniently, is a builder, too. On one level, I feel it will be better and more fun to keep it in the family, so to speak, but I fear the opportunities for falling out could be limitless. Maybe I should just make an offer for the tree house instead. I know I'd be very happy living there, even if it is in Clapham. I wonder whether Will is open to offers.
'Green Up! - an A-Z of Environmentally Friendly Home Improvements' by Will Anderson, Green Books, £7.95