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How long should we wait to get an idea of our energy usage after adding spray foam insulation over the entire house?
Flying Hippo / November 16, 2016
It is suggested that you wait 12 months after you’ve added spray foam insulation and then compare energy bills 12 months prior to that to see the yearly energy savings/improvement. If possible, get a full year of data including two summers since the summer months often dictate the highest usage and the months when the foam insulation will have the greatest impact on the electric load, assuming that gas is used for heating.
Iowa Energy Center Staff