New House Windows: Energy Savings

In May 2009 we replaced the windows in our house from single pane original 1975 windows to double pane low energy windows.

Please note that in 2007 when we bought the house, we had a heat pump installed.  As a result, our baseline energy usage is lower/more efficient than if we just used our natural gas central air furnace (the furance was installed in the late 1990’s as far as I can tell).  The heat pump using electricity to extract heat from the air outside the house (and cools the house in the summer too). 

We are also located in a mild temperatured suburb of Vancouver BC Canada.

Here is the math on our energy usage and windows.

Since we got our new windows:

Electricity: Down 30% kWh/day

Gas: Down 46% GJ/Day

Our records go from July 2007 to May 2009 (new windows) and then to now.  I keep them in a spreadsheet.

With our yearly energy bill, that's about $1000/year saved.  Without a heat pump, that number would probably be MUCH higher.

The new windows will pay for themselves in about 9 years.