It looks as though this small scale wind power will not only not generate much electricity, but will never pay back the energy costs of its own production. To add to which, a nice drag like that attached to your house in a gale will sooner or later cost you a new chimney stack and roof.

Direct solar water heating- low tech, unobtrusive, cheap and easy to make at home- is one of the better ways to "make a contribution". But like most of these things, you only really get much hot water when it's a bright sunny day, which is when you least need it.

It's a bit like growing beans or tomatoes: when yours are ready, they are practically free in the shops.

You can use low energy light bulbs- OK in many cases, we can put up with the weird light and the warm-up time- but the typical saving not overwhelming. If you have 3 rooms, 3 60W lights in each, on for an average 5 hours a day 365 days a year, that's 800kWHr saved by replacing them with 11W low energy bulbs. According to this web page, each kWHr gives about 170g CO2, that's a saving of 136kg CO2.

Assuming petrol's chemical formula approximates to -CH2-, burning petrol produces 3.142 (*) times its weight of CO2. The density of petrol is about 0.8 times that of water, so each (UK) gallon of petrol produces about 11kg of CO2. Your 136kg saving could be as well produced by using 12 gallons less petrol, or driving just 8.5 miles a week less at 35mpg.

I don't know where the big savings are to come, and rather despairingly think it may be only by people becoming gooder, in which case it won't happen.