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Passive Solar Design: How South-Facing Windows Help

Passive solar design or climatic design uses solar power without the use of panels or other mechanical systems such as fans, pumps and electrical controls. To maintain a comfortable indoor temperature, passive solar homes collect heat from the sun shining through south-facing windows and retain it in material that stores heat, also known as thermal mass.

Passive Solar Design

In this article, Renewal by Andersen® of Montana, known for quality window replacement services, explains the role of south-facing windows in passive solar design and how you can maximize them. 

Seasonal Considerations for South-Facing Windows

Depending on your home’s location and climate, make sure you keep the following seasonal considerations in mind:

  • Winter. During the heating season, south-facing windows should not be shaded so your home can collect solar energy and store heat. However, windows still let heat escape due to their thin and transparent nature. To keep this from happening in cold climates, window contractors recommend getting windows with double glazing. An insulated window covering or thick shade can also be used to keep the heat inside your home after the sun sets. 
  • Summer. During the cooling season, your passive solar home uses its thermal mass to keep the building cool. Thus, in the summer, a proper overhang or other systems are required to shade or cover windows. This way, the sun’s heat energy is blocked, preventing it from heating your home. 

How to Maximize South-Facing Windows

To get the most out of your south-facing windows, you need windows that offer year-round energy efficiency. For this reason, consider investing in double-paned low-E windows to minimize infrared and ultraviolet light. The window glass has a colorless coating to keep thermal transfer to a minimum and ensure consistent indoor comfort.

Furthermore, low-E windows are not only beneficial for south-facing windows. When placed on the northern side of your home, for example, your windows can reduce heat gain in the summer while letting in natural light at the same time.

Harness the power of energy-efficient windows for your passive solar home design with the help of Renewal by Andersen of Montana. Count on our team of experienced design consultants and installers to ensure a positive window replacement experience. Call us today at (406) 259-3944, or fill out our online contact form to schedule an in-home 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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