A Day in the Sun

February 18, 2014

As a child playing in the creek on hot summer days, it was a treat to climb out of the cool water just to lie on the sunlit rocks as they fed their slow, steady warmth into my skin. I didn’t know it then, but there’s a term for the build up of heat in an object or space resulting from exposure to the sun—solar gain. You’ve felt it, too, right? Sunlight pouring through the widows of your classroom, heating it like a greenhouse as snow drifts just outside of the glass. Or, when the sun beats through your driver’s side window and bakes the left side of your face as the right stays cool.

This heat load attacks buildings from all sides, but is usually hotter on the south- and west-facing sides of the building’s exterior surfaces, or envelope, and is generally cooler on the north and east sides. Just imagine the effect this has on the various parts of the building’s heating, cooling, and electrical systems—and you!

Armed with this knowledge, today’s architects and engineers approach building construction more scientifically than ever before. Solar gain is a serious consideration in the beginning stages of design, and this is dealt with early on through building orientation and site location. In 1965, the year I was born, few professional builders ever considered these simple concepts in the construction of their buildings. As a result, we now employ retro-commissioning, a remedial program intended to correct the flawed designs and renovations of the past.

By fine-tuning the mechanical and electrical systems within a building’s envelope, engineers can enhance the comfort of the occupants and cut operating expenses. The process takes all data points into consideration to promote comfort and savings: windows and doors are kept closed; lights are turned on or off, depending on suitability of natural light and sun positioning on room; and, classroom temperatures are normally set cooler than hallways due to entry and exit use. It takes all parts of the system working together to have a healthy and efficient building.

As effective as retro-commissioning can be, it definitely takes the active participation of a building’s occupants to fully realize the many financial and “liveability” benefits of the program The sun’s energy has tremendous potential, and we can make it work for us or against us!

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