A Storm Door Is NOT a Wise Home Energy Efficiency Improvement
Although I rarely get to listen to it these days, I love the show Science Friday with Ira Flatow on NPR. It's always interesting, and you get to learn cool new science stuff. This past Friday, they covered a topic near and dear to my heart: the federal tax credit for home energy efficiency improvements.
Briefly, you can get up to $500 as a tax credit (which is real money, as opposed to a tax deduction) for home energy efficiency measures you pay for. It used to be $1500 and 30% of the cost, but they reduced it to $500 and 10% of the cost for this year. It's not great, but it's something, so if you can get it, you should.
The whole point of the latest edition of Science Friday was to make their listeners aware that this tax credit is expiring at the end of 2011. Yes, it's going away...again. Maybe Congress will extend it again, or maybe they won't. If you want to take advantage of this federal tax credit, you need to do it soon.
So, what does this have to do with storm doors, you're wondering? Well, in the show, the very first home energy efficiency improvement mentioned on Science Friday was installing a storm door. Yes, a storm door. They mentioned other items afterward that were better, but a storm door? Really, Ira?
Here's why I don't recommend storm doors for saving energy. If you want a storm door to protect your door or for looks or because everyone else is doing it, fine. Those are better reasons than getting one to save energy because they won't do a whole lot for you. In fact, you may use more energy if you do what so many do and leave the main door open and use your new storm door as a single pane window. A standard door doesn't have a lot of R-value, but it has more than a single pane of glass.
The main reason it won't save you much energy is that, you don't have a lot of energy use associated with your doors. Take a look at the pie chart above. It's from a home energy rating for an energy hog of a house in Atlanta. In that house, the heating and cooling loads due to the doors in the house added up to only 1% of the total. I'm not a big fan of looking at payback (and if you're financing, payback is irrelevant), but the payback on a storm door is not very good. In the house above, the payback on a $200 storm door would be at least 20 years.
So, forget the storm door. Go with the caulk, spray foam, mastic, and weatherstripping first. Sealing the air leaks is the place to start.
(By the way, Ira, if you're looking for someone to discuss building science on your show, I could find some time for you. Give me a call.)
Photo of storm door by Corey Ann from flickr.com, used under a Creative Commons license.