Solar Orientation Impacts a Home’s Comfort and Energy Efficiency

Solar Orientation

I was sitting in the Baltimore Washington International airport recently and I was emphatically (and painfully) reminded of the importance of proper solar orientation in building design. Whoever designed this airport must have been tone deaf to solar orientation. And they probably never heard of passive solar design.

Concourses A and B in the airport are connected by a large, glassy structure with shops, food service, and the waiting area for gates A1 through A5. It is an attractive arrangement and the tall, curving glass wall gives travelers a grand view of the runway and airplanes coming and going. The problem is the direction the glass wall faces. It aims directly southwest. Because of that, the afternoon sun pours unabated through the glass, making it very uncomfortable to sit in the space.

The glare of the sun is so intense, it is difficult to read and nearly impossible to use a computer. As the sun sets, it gets lower in the sky and the direct sunlight reaches even further into the building. Ironically, if the windows had been designed to face directly south, a proper roof overhang could have been designed to shade the glass, much like the brim of a baseball cap shades your eyes, because the midday sun would have been much higher in the sky. But because the windows face southwest, an overhang, even a very large one, would do little to shield the interior of the building, and the suffering passengers, from the onslaught of the low afternoon sun.

There is a lesson here for house design. Problems like this can be avoided by thinking through the solar orientation your house should have at the very beginning of the design process. Think about where the sun will rise and set. Consider which room you might like to have the sun come into the first thing in the morning. Plan where you might like to sit in the evening and how the setting sun will impact that area.

Proper solar orientation will save you energy and money. This is the essence of passive solar design. It has a big impact on how hard your air conditioner or heater will have to work. You can save a lot of money by letting the sun help heat your house in winter, especially in northern climates. And properly shading your house from the hot summer sun can save a lot of air conditioning costs. Most important of all, well thought out solar orientation will make your house a comfortable and enjoyable place to live.

Bill Hirsch

Bill Hirsch

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