The weather in Boise can be a rollercoaster. Summers hit triple digits for days on end. Winters dip into the teens or single digits at night. It can be hard to keep your home a comfortable temperature without spending a small fortune on energy bills.
Windows are one of the biggest sources of heat loss and heat gain. In the winter, your home can lose 30% or more of its heating energy through windows. In the summer, direct rays from the sun can make the rooms on the south and west sides of your home feel like a greenhouse. By choosing proper interior and exterior window coverings and being strategic about using them, you can save money on your bills and keep your home feeling much more comfortable.
A great resource for window covering information is from Energy.gov
Shades & Curtains
Simplest solution, renter friendly
These reduce day and nighttime heat loss through windows when it’s cold and reduce unwanted solar heat gain through windows when it’s hot. They also reduce cold drafts near windows.
Insulated cellular shades have the highest R-values (insulative values) of all window coverings. The honeycomb cross-sections are filled with air pockets, which act as insulation. Make sure they fit tightly inside the window trim; the best overall R-value shades operate on side tracks. If you can, look for products certified with the Attachments Energy Rating Council (AERC) Energy Improvement rating.
Pelmets & heavy curtains also work well to prevent temperature fluctuations from solar heat gain and loss. Studies demonstrate that draperies with white-plastic backings can reduce heat gains by 33% during the summer. And using a pelmet across the top will keep your room warm and cozy during the winter. Warm air sinks on the curtain side of the windows rather than against the cold glass, keeping the warm air to the inside of the curtains, rather than losing heat through the window pane.
Don’t forget to open your shades & curtains during winter sunlit hours! Heat gains from the sun in wintertime are helpful for warming your home. Some companies offer window coverings with automated options. But if you’d rather save some money, set a reminder on your phone to open & close your window coverings until it’s a habit.
Awnings & exterior shades
Intermediate solution, needs a little DIY know-how
76% of the sunlight that falls on double-pane windows enters your house as heat. To truly cut out solar gain, prevent the sun from hitting the glass in the first place! Awnings and exterior shades provide the benefit of shading windows during the summer, while still allowing daylight and views through your windows.
Awnings are projections on a home’s exterior that shades windows from the sun. They can be fixed or retractable, and are typically either metal or a synthetic fabric material. If they are fixed awnings, make sure to size them effectively so that they block summer sun angles, but allow winter solar gain. A great tool to play with is here - in general for Boise’s latitude, try to keep the depth of south-facing overhangs at least 1/2 of the height of the window. And the wider you make it, the more of the window will be protected from the sun in the mornings and afternoons.
Bahama shutters, also known as Bermuda shutters, are storm-resistant types of exterior shades that have been used in hurricane-prone areas for centuries. They hinge from the top of windows and can be closed tight against the window when a storm is approaching. Most models have louvers to give some transparency and airflow since they hang in front of windows. They aren’t the best option for promoting solar heat gain in wintertime, but if you are looking to combine shading, storm resistance, and privacy for your exterior window coverings, they are a great option.
Exterior window shades are a synthetic fabric screening that rolls up into a protected valance at the top of the window. Solar heat gain through the shade depends on the openness of the fabric weave and on the transparency of the fabric itself. Roller shades are most commonly lowered or raised by hand; some are operated from the outside, and others can be operated from inside using a through-the-wall crank. The shade frames are typically anchored in place, but some low-cost systems attach manually using suction cups, Velcro, or snap systems.
fast ideas
for emergency heat events
The low-cost exterior temporary shades presented above are an EXCELLENT measure to have on hand for heat waves or heat domes, even if you don’t plan on using them regularly. In a pinch, a light-colored sheet tacked around the outside of your window frame could serve the same purpose. Anything that helps keep the sun off your glass!