Good design will save energy
Architect About Town - Special to the Fort Myers News-Press
This past month I did an “energy audit” on my house and identified the things that needed to change to bring my bill down.
I’m fortunate; I live in a 1950s house successfully designed for the Florida climate. We already have low cooling costs and though the air conditioner is old, it’s not used enough to justify a new one, even with the federal tax credits available. My appliances are Energy Star and we use minimal hot water.
So, a few minor adjustments to the lights and fans made us about as efficient as we can get in a hot and humid climate.
Why is it that some buildings are naturally more energy efficient than others?
Designing for the climate makes it possible to save energy and money in the long run. But don’t listen to the snowbirds about how they build up North. In the Sunshine State, it’s often necessary do just the opposite.
Take “passive solar” design. In most of the country, passive solar refers to maximizing sun exposure, and saving the heat generated by the sun as a method of supplementing heating systems. The warmth captured in the day is saved for heating at night.
Whether remodeling or building new, in the home or place of business, passive solar design in Florida is about simple design considerations that significantly improve cooling, not heating.
From the start, consider the orientation and how the angle of the sun affects a building. Remember the sun’s location in the sky changes with the seasons: in the summer the sun is high and in the winter it is very low.
This far south, it is essential to keep the sun out three quarters of the year. In the winter, when it is low, it can be used in small amounts, to warm buildings.
As a general rule of thumb, orienting the length of a building east to west is best everywhere.
However, in the South, exposing the long southern wall to the sun maximizes heat gain. Using substantial overhangs or a porch can effectively shade the wall and the windows. Carefully locating landscaping works equally well — two huge live oaks in my backyard keep the roof and south wall shaded all day long.
At the very least, ensure all windows on this side are protected with sunshades, awnings, shutters or sun control films.
It’s important to be strategic when locating windows and doors. The north side is for daylight: lots of windows, great light, and less energy needed for artificial light.
In Florida, east and west facing walls are traditionally difficult because the strongest sunlight comes in at a low angle, especially late on a hot afternoon. These should be the short sides of the building. Use fewer, smaller windows or consider locating porches or balconies on these ends as well. They shade walls exposed to a variety of sun angles, and can help cool the air before it comes inside.
To minimize the heat gain of the late afternoons, locate the garage or storage space on the west side for an effective insulator between the hot sun and air-conditioned spaces. My open carport and walk-in storage room in the west side completely shield me from the searing western sun.
For roofs and walls, down here, the lighter the color the better, and reflective materials such as metal roofs are ideal.
Know enough? Go ahead and conceptualize your next building, or do your own energy audit on the one you’re in to make it more energy efficient.
Now you know the principles that drive my designs — except we didn’t discuss methods of building to keep the cool in, the hot out or how the inside can encourage the exchange of air: cool air replacing hot air.
There’s a whole other set of considerations that reduce the consumption of energy. I’ll talk more about that next month.
Joyce Owens AIA RIBA