Not only is it socially responsible, but R/E portfolios are going to be some of the hottest tickets going, with great returns. Talk to an investment counselor about getting in on these investments. Ask about "white hat" mutual funds, which are heavy on R/E stocks, along with other socially responsible stocks. Check Sustainable Business for some great R/E investing tips<
http://www.sustainablebusiness.com>.
Also be aware that some of the companies you invest in will be owned by the evil oil companies. Shell and other petro companies have quietly gotten into solar energy in a big way. Don't panic, invest in them anyway, since it is a great, capitalistic way of supporting their R/E moves. Offer them the carrot instead of beating them with a stick.
And socially conscience, R/E investments are generally less susceptible to market fluctuations. And since most of these companies are ethics driven, they are much more free of the corruption that plagues modern corporations, ie cooking the books, misstating profits, etc. And hey, your return on investments is generally as good, if not better, than regualr investments.
You are doing a great move, and don't let the naysayers talk you and your wife out of it. You'll never regret it. One word of warning though, like all investments, do your research, for there are a number of hucksters out there who will try and use your good intentions to their own gain. But that is true of any investment.