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Window Size: What’s the Right One for Your Home?

When choosing new windows, whether to increase the energy performance or simply boost the curb appeal of your home, there are a number of important factors to take into account. One of them is the size of the window. According to replacement window specialists, the most appropriate size of windows for a smart energy design can be guided by thermal mass and orientation.

Window Size

Thermal Mass and Window Size

Thermal mass refers to the ability of a material to absorb heat. A high level of thermal mass is required to alter the temperature of high-density building materials like brick, tile, and concrete. Therefore, these materials are considered to have high thermal mass. On the other hand, lightweight materials such as timber do not store and absorb heat and are said to have low thermal mass.

Homes with higher levels of thermal mass, such as tile flooring or brick interior walls, can significantly benefit from custom windows with larger areas of glass. Meanwhile, homes with lower levels of thermal mass will be better off having windows with smaller areas of glass.

Building Orientation and Window Size

In order to maximize the heating benefits of the sun during the winter season, consider installing large-sized windows oriented toward the north. In the summer months, the sun is at a higher angle in the sky, so north-facing windows can be easily shaded with awnings and eaves. Contrastingly, south-facing windows receive no direct daylight in the winter months, though early morning and late afternoon sunlight in the summer is present. To prevent heat gain in the summer and heat loss during colder weather, keep south-facing windows small. East- and west-facing windows should also be small in size to reduce hot temperatures in the dog days of summer.

Renewal by Andersen of Montana is a premier source of beautiful and energy-efficient replacement windows, from traditional double-hung and casement windows to custom picture windows. Call our certified team of installers at (406) 812-8167 or fill out our online form to schedule your consultation.


"I highly recommend Renewal by Andersen. We were treated well and everything went smoothly from start to finish. The company kept in contact with me before, during, and after the installation and let me know what to expect. I'm in love with my new windows! I will be using this company again when we refinish our basement. "

July, 21

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