Buildings

Comforting Compromises

Q: My wife and I are planning to have a house built, and we can't agree about air conditioning. I want to build a very energy-efficient house and put in the most efficient air conditioning system we can afford. My wife points out that the old house we've been living in for fifteen years isn't very well insulated, leaks air like a sieve, and doesn't have air conditioning at all, yet stays comfortable most of the time. She also doesn't like air conditioning. When she gets home from work after being "trapped" in a closed-up office all day, she wants to open all the windows and breathe fresh air. Even though our old house is tolerable most of the time, I can't imagine building a new home without air conditioning. Is there any way to satisfy both of us?

A: My old Dodge Dart didn't have air conditioning, and I was perfectly comfortable as long as it was moving. It had vents in the side walls down near the floor, and whenever the car was moving, air moved over my body. The car was designed to be tolerable without air conditioning, and it worked--except, of course, when I was caught in a traffic jam and had to sit still with the sun beating down and the relative humidity hovering at 90%. Newer cars, on the other hand, weren't designed to be comfortable without the a/c--and they're not.

Houses are similar. Many older houses, particularly in the South, were designed to provide some degree of summer comfort before air conditioning was invented. While some of them were very successful, most were marginal, which is why air conditioning has become so popular.

One way to look at your question is to ask, "Is it possible to build a house today that will be comfortable without air conditioning?" The answer is "Yes," "No," and "It depends."

The problem is that "comfort" is very subjective. Engineers can define ranges of temperature and humidity that most people will experience as "comfortable." But engineers can't take into account other very real factors, like the fact that being all closed up makes your wife very uncomfortable, regardless of the temperature and humidity. The challenge is to design a house that meets both your needs and hers. This is very different from a compromise that will satisfy neither of you.

There are four strategies you can blend together to get the house you want. First, keep as much of the heat and humidity out of the house as possible. Make sure the house is well insulated and tight. Shade the house, particularly any windows on the west and east sides. Second, design the house to make maximum use of natural cooling techniques. Together, these two approaches will greatly reduce the amount of time air conditioning will be required for your comfort. Third, install a controlled mechanical ventilation system to keep fresh air circulating throughout the house even when it is all closed up. And finally, "zone" the air conditioning system, so that when all else fails, each of you can retreat to different parts of the house for relief. If you follow the first three strategies, you won't have to use the fourth very often.

Look closely at your old house and think about what features it has that make it more comfortable in the summer. Are the windows, particularly on the west and east sides of the house, shaded by overhangs, porches, trellises, trees, or awnings? Are there high ceilings? Are windows and doors arranged to give you cross-ventilation in every room? Do you have ceiling fans in each room? How about a whole house fan? Or a nice cool stream with a deep swimming hole? These traditional cooling techniques can make the house perfectly comfortable in the early fall and late spring for most people, extending the non-air-conditioned period. Clearly, it will work for your wife. You need to decide if it will work for you.

Designing and building a house that works well both with and without air-conditioning takes more thought and planning than is usually given to these issues nowadays. You have to look at everything from landscaping and shade trees to window types and lighting fixtures in a slightly different way. But it's definitely do-able and doesn't have to add a lot of cost to your budget.