Homeowners can now receive a federal tax credit for 30% of the cost of new energy-efficient windows. The credit was authorized by the American Recovery and Reinvestment Act (ARRA) signed by President Obama in February.
There’s just one problem with the new tax credit: the specifications for eligible windows were crafted by politicians, not window experts. The ARRA stipulates that eligible windows must have a maximum U-factor of 0.30 and a maximum solar heat-gain coefficient (SHGC) of 0.30 — requirements that have been dubbed “the 30-30 provision.”
Only low-solar-gain windows are eligible
There’s nothing wrong with the U-factor specification — except, perhaps, that it isn’t particularly stringent. The problematic provision is the SHGC spec.
By setting a maximum SHGC of 0.30, the ARRA actually excludes the best windows for cold climates. Cold-climate homes need windows with a SHGC in the range of 0.39 to 0.65; so if they comply with the tax-credit provisions, they’ll end up with windows that contribute to higher-than-necessary energy bills.