Tax and Tax savings on home improvement

Sometimes you have just got to run the numbers to see if something will save you money or not, so, I strongly suggest you do that before running out and making a big purchase...but let me tell you about my situation.
After the divorce, I did add on to the house (which costs money) for two main reasons...1) my house was a 2 bedroom house and I have 2 sons who won't always want to share a room 2) I spent an evening in my creepy cellar and vowed I would never do that again.... Here are two (or three?) ways in which I am able to save some with a home addition (Perhaps home improvement with you?)
1) Federal taxes allow for a deduction for a portion of any energy-saving improvements to your property. One just has to make sure the product you are installing qualifies. In my case, the windows applied (energy-efficient), which gave a me a small federal tax savings. Hey, every little bit counts, right?
2) When the old portion of my house was remodeled, the 100+ yr old sashes were replaced with new energy efficient windows selected to look like the old windows (nothing is more unappealing that modern windows made to fit the odd-size of older homes) I custom-ordered the size (just a few dollars more than off the shelf) so they look original. This has saved me money on my electric bill. My house also stays cleaner, too.
3) Our county has a tax rebate program on additions and improvements made to your property. Basically, you pay no property tax on the improved or added portion for 5 years. This is a big savings, too. One would have to check availability of local programs....