What the heck is solar heat gain coefficient and why should I care?

Solar Heat Gain Coefficient (SHGC) is basically how much free heat from the sun your windows let into your house - and in Ottawa's climate, getting this right can save you hundreds on energy bills every year.

SHGC is measured on a scale from 0 to 1, where a lower number means less solar heat gets through. Think of it like sunscreen for your windows. A window with an SHGC of 0.30 lets in 30% of the sun's heat, while blocking 70%. The key is finding the sweet spot for Ottawa's four-season climate where you want some free solar heating in winter but don't want to turn your house into a greenhouse in summer.

For Ottawa homes, the ideal SHGC typically falls between 0.25 and 0.40 depending on your window orientation. South-facing windows can handle higher SHGC (around 0.35-0.40) because you want that winter sun streaming in to help heat your home during those brutal February cold snaps. But west-facing windows should have lower SHGC (0.25-0.30) since they get hammered by afternoon summer sun that'll make your air conditioner work overtime.

Here's why you should actually care: A house with poorly chosen SHGC can cost you $200-400 extra per year in energy bills. Windows with too high SHGC will overheat your home in summer, forcing your AC to run constantly. Too low SHGC means you're missing out on free solar heating in winter, making your furnace work harder. Quality triple-pane windows with properly selected SHGC can reduce your heating and cooling costs by 15-25% compared to old single-pane windows.

When shopping for replacement windows in Ottawa, look for ENERGY STAR certified windows that meet our Climate Zone 6 requirements - they'll have SHGC values optimized for our climate. The Canada Greener Homes Grant program also considers SHGC when determining rebate eligibility, so choosing the right coefficient could put money back in your pocket.

For a free consultation on selecting the right windows with optimal SHGC for your Ottawa home's specific orientation and needs, Ottawa Window Pros can help you maximize both comfort and energy savings.