In Chicago, there are three constants in life: death, taxes, and heating bills. You might be able to reduce/eliminate the heating bill portion by using solar power. Many of the solar energy sites around the city and region are offering open-houses this weekend so you can see how people in Illinois put the sun to good use. There is a clickable map to illustrate the tours available, or you can look at the tour list if you want to see the addresses of the sites sponsoring tours.