A lot of the energy saving websites offer decent, generic info, but not enough for the serious energy efficiency DIYer. Those of you who have read the FAQs and guides of their local utilites know what I'm talking about: I don't need to be told to run the dishwasher only when I have a full load or that my furnace will run more when it's colder outside. Feh. I want to know estimates of how much new windows with a low U rating will impact my natural gas bill, and make sure the estimates account for the trees in my yard and the orientation of my house. I want a tool that factors in the shape of my house, number of doors and skylights, and the color of the shingles on my roof. And I don't want to pay someone $300+ to do an energy audit on my house either--I can handle the details.
Enter the Home Energy Saver:
This U.S. Dept. of Energy website is basically a free, web based version of the expensive software packages engineering consultants and utility companies use for energy audits. The HES allows steps you through the usual home energy audit questions and produces a good report when complete, but the amount of customization it offers the DIYer is unmatched by any other website I've found. You can run it in a fairly generic mode to produce an overall report, then continue to refine the model as you gather details about your house and plug them in. Each time you make changes, you can rerun the simulation and see the how your report changes. It also assigns you a session ID that you can use to continue working on your simulations at a later date, without having to reenter all of your settings. The HES simulation of my house produced an estimate of yearly energy costs that was within 8% of my actual costs, so the HES calculations and data it are pretty accurate.