How Passive Solar Building’s Windows Save Energy in Different Climates


The windows in a passive solar building are designed to collect, store, reflect and distribute solar energy.  During winter, the windows help keep the heat in by maximizing the heating rays of the sun. During summer, they reject the solar heat keeping it out and the cool in. 

Since there are different climates all over the world, the windows need to be positioned and installed accordingly to take advantage of maximum solar energy on the various properties.

Using Windows in Cool Climates

Keeping a green building warm in a cool climate can present a challenge. The two main strategies used for passive solar energy through the windows: one strategy is using Trombe walls and the other is using various green building methodologies.

Trombe walls are usually big walls built on the winter sun side of the building, maybe painted black, to allow for absorption of heat into the building without leaking heat out.

Since one main concern with using a big window is that while the sun's rays come in the building and heat up the air, the glass conducts heat so well that the heat may escape back through the glass. By using a Trombe wall, this issue is resolved because the Trombe wall traps the heated air between the glass and the wall, then circulates it back into the building before the heat has a chance to escape through the glass. 

The green building methodology uses technology to keep heated air inside the building. Therefore, this methodology uses numerous windows to allow the sun’s rays into the green building. Then to optimize the heat from the rays and reduce the amount of lost heat through the same glass, a controlled timer is used to circulate the air within the building.

Using Windows for Hot and Sunny Climates

Since keeping a green building cool in a hot and sunny climate is often a difficult task, installing glazed windows toward the south side of the building is one methodology used. This prevents the building from overheating during peak hours of the day because the windows collect the rays while the sun is low in the sky.  

Another methodology is the use of awnings, overhangs or other shielding devices to help prevent excessive heat during the summer.  

While other windows may be installed in the building, in order to not allow light or heat into the building, they should have a glaze or a shade installed.  Plus, to prevent overheating in a hot, dry climate, avoid north-facing windows.

Using Windows Wisely

Correctly using windows in any green building can work for both cold and hot climates, providing needed warmth or cooling, whether there's a lot of sun or just a little sun.

Since purchasing energy efficient windows for a passive solar building is a substantial investment, the long-time energy savings will provide a nice return on the initial investment. To determine the best options and whether or not your building will benefit from passive windows, it is always best to talk to an environmental contractor or engineer in your area.


Michael Tobias PE is a visionary in the construction industry. His passion resonates as the Founding Principal of New York Engineers, an Inc 5000 fastest growing company. New York Engineers is the most innovative construction engineering firm focusing on Mechanical, Electrical and Plumbing (MEP) engineering designs in Chicago and New York. Michael has overseen the design of over 1000 construction projects in all market sectors, including LEED certified and Passive House certified projects. He leads a global team of 50 top performers.

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