May 19, 2010

Upgrading Windows to Save on Energy

When we got our home energy audit they said that our windows were fine and it didn't make sense to replace them.   We were told the same thing by at least one or more of the contractors that gave us estimates for the insulation work we had done.  Our windows are double pane and the house is not very old.   Theres no drafts around the windows and they're all in pretty god shape.   Windows are a pretty expensive item to replace  and I was doubtful that improving our windows would save us much.  

The Energy Star site has a map of the USA showing energy savings for various regions.   For each region they give a figure upgrading from single pane or double pane.  For example if you live in South Atlantic region then you'd save about $213 on average if upgrading from single pane and $86 average upgrading from double pane.   I'd only be upgrading from double pane and given my region I'd save barely over $100 a year.   These are just average figures so they are more of a ballpark estimate.

Its hard to get good solid information on the cost of windows.   Window costs are quite variable due to various sizes and quality.   Costhelper cites costs of $300 to $700 for window replacement.  My house has 10 windows so that means I'd be looking at $3,000 to $7,000 to replace our windows.   If I were to save $100 per year then that is only 1.4% to 3.3% return.   Rough payback period would be 30 to 70 years.  Thats not a very good return and I have other home energy saving improvements that would make more sense to do first.

If I lived in a colder climate and had single pane windows then it might make a lot more sense to replace my windows with new energy efficient ones.    An average house in New England could save about $501 a year by replacing single pane windows with new Energy Star windows.   If the house is similar to mine and we use the guesstimate cost of $3000 to $7000 to install new windows then that would be a 7.1% to 16.6% return and 6 to 14 year payback.    Thats a lot better return and would be a smarter move than some other home energy savings improvements.

In general it looks to me that replacing single pane windows in a cold climate could be worth the money, but replacing double pane windows or replacing windows in mild climates is likely not a high priority energy saving improvement.

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