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Does closing blinds keep house warmer in winter?

Quick Answer

Yes, closing blinds and curtains during the winter can help keep a house warmer. When closed, blinds and curtains act as an extra layer of insulation by trapping air between the window and the window covering. This extra air layer helps minimize heat loss through the windows, allowing less cold air in and more warm air to remain inside. Blinds and curtains can reduce heat loss through windows by anywhere from 10-25%, helping significantly cut heating costs during cold weather.

How Do Blinds Help Insulate Windows?

Blinds, curtains, and other window treatments add an extra layer of insulation and protection beyond just the glass windows alone. Here’s how they help reduce heat transfer:

Trapping air: When closed over windows, blinds and curtains prevent warm indoor air from escaping out through the windows. The trapped air creates a insulating buffer zone between the window glass and the window covering.

Reflecting light/radiation: By reflecting light and radiant heat back into the room, window coverings minimize the amount of heat absorbed and conducted out by the cold window glass. Reflective blinds and light colored curtains work best for reflecting heat.

Reducing air flow: Blinds and curtains eliminate drafts and air currents around the window edges that allow hot air to escape and let cold air in. They seal and fill air gaps that make windows poor insulators.

Offering shade: During the day, closed blinds can block out intense sun rays that would heat up the house in summer but help warm it up in colder months. Proper shading reduces heat gain/loss through the windows.

So in summary, window coverings like blinds help insulate windows by trapping an air layer, reflecting heat back inwards, sealing air gaps, and providing shade. The added insulation value helps reduce conductive, convective, and radiant heat transfer through the windows.

How Much Do Window Coverings Reduce Heat Loss?

Tests have shown window coverings can reduce heat loss through windows by 10-25%:

– A University of Massachusetts Lowell study found interior window coverings reduced heat loss through windows by an average of 10%. Reflective blinds and blackout curtains offered slightly better insulation.

– Researchers in Norway tested heat loss through windows covered by curtains and roller blinds. The window coverings reduced heat loss by 10-25% depending on type.

– A study by the U.S. Department of Energy showed that insulating cellular shades limited heat loss by 18-33% compared to uncovered windows.

So on average, you can expect properly installed window coverings to cut heat loss through windows by 15-20%, although results vary based on the specific product used. Even temporary solutions like hanging blankets over windows can provide noticeable insulation.

Should Blinds Be Open or Closed During Winter?

To maximize insulation and heating benefits in winter, it is generally recommended to keep blinds and curtains closed during the day and open at night:

– Keep them closed during the day to block cold outdoor air and prevent warm indoor air from escaping. This helps maintain the warm temperature inside.

– Open blinds and curtains at night to allow heat absorbed in walls, furniture and other objects during the daytime to radiate out through the windows. This re-releases warmth into the house that would otherwise remain trapped in objects.

There are some exceptions depending on conditions:

– On cold but sunny winter days, leave south/west-facing blinds open to let warm sunshine heat up the house. Close other blinds to minimize heat loss.

– If outdoor temperatures drop extremely low, it may be better to keep blinds closed both day and night.

– Smart blinds that automatically adjust throughout the day based on the weather and sun position provide optimal insulation.

Open During Day or Night – Which is Better?

Here is a comparison of whether it is better to open or close blinds during the day versus night in winter:

Time Open or Closed Benefits
Daytime Closed – Traps heat inside
– Prevents drafts
– Reflects light/radiation back in
Nighttime Open – Allows stored heat to radiate out from walls and furnishings
– Cools house down to reduce overnight heating needs

So in summary, closed blinds during the day help insulate and retain heat, while open blinds at night can release excess warmth stored in the house’s structures and materials.

Tips for Maximizing Heat Retention from Blinds

To get the most heating benefit from window coverings in winter, consider these tips:

– Use thick, insulating drapes or thermal blackout curtains to provide maximum heat retention.

– Ensure curtains fully cover the window and overlap the wall by a few inches to seal air gaps.

– Install plastic film underneath curtains to create an additional sealed air pocket.

– Use wood or insulated aluminum blinds, which offer better insulation than vinyl or plastic blinds.

– Close vertical blinds completely and rotate slats to seal gaps.

– Add draft blocking strips at window edges and use pole extenders to fully seal blinds.

– Install cellular/honeycomb shades for their superior thermal performance.

– Use window insulation kits between the glass and blinds to create extra air pockets.

– Keep blinds dust-free as dust accumulation reduces their insulating capacity.

– Supplement blinds with additional window insulators like thermal curtains.

– On sunny days, open southern facing blinds to let warm sunlight in.

Properly insulating windows with blinds, curtains, and other coverings can make a home more comfortable while also providing big savings on energy costs during winter.

Other Ways to Reduce Heat Loss Through Windows

In addition to window coverings, some other options to decrease heat transfer through windows include:

– Installing double pane or triple pane windows with an insulating gas fill like argon or xenon.

– Adding a low-e (low-emissivity) coating to window glass to reflect heat back into the home.

– Using window insulation film kits that layer plastic sheets over the glass.

– Placing removable acrylic panels or plastic sheets over windows.

– Filling window frames with rope caulk or insulation strips to seal air leaks.

– Installing exterior storm windows over regular windows to create an air gap.

– Attaching window insulation boards (rigid foam panels) over window frames during winter.

– Keeping windows locked to eliminate air gaps.

– Drawing curtains 2-3 inches from the window to allow air circulation and reduce condensation.

– Upgrading to modern energy efficient windows with features like double glazing.

Using a combination of proper window coverings and other insulation methods can help maximize energy savings.


Closing blinds, curtains, and other window coverings during winter is an effective way to reduce heat loss through windows. When closed over windows, blinds trap air and act as an extra layer of insulation that prevents warm indoor air from escaping out through the glass. Tests show that window coverings can lower heat transfer through windows by 10-25%, providing significant energy savings. For best results, close blinds during the day and open them at night in winter. Supplementing window coverings with other insulation techniques like weatherstripping and plastic film can further minimize heat loss and help keep a home’s interior warmer in the winter cold.