If you're not yet giving much thought to how much energy your new house is going to use, and how much it's going to waste, then it's time you started. It should be one of your top priorities – if for no other reason than your own pocketbook. Energy used for heating and cooling homes is going to continue to get more expensive and as we've seen recently, world politics can quickly and dramatically affect your access to cheap energy. Saving energy isn't just about saving money. It's also an important part of good design.
A Little History
This isn't the first energy crunch we've had. In the 1970s, when I was a college student studying environmental design, world events conspired to create an American energy crisis. It was an interesting time to study architecture, because the buildings we designed were required to respond to the environment by using natural energy sources as much as possible.
The homes we created used technology and inventive design to give them form. We designed solar homes, earth-sheltered homes, thermal-mass homes, and other types in a wide variety of shapes and sizes. They collected heat from the sun and the ground and held it inside as long as possible. They blocked excessive solar radiation with deep overhangs and shading devices, and they were very carefully oriented to the angle of the sun and prevailing winds.
Sure they looked a little weird (some were downright ugly) but we designed homes that stayed warm in the winter and cool in the summer and used almost no energy at all.
But then in the 1980s energy got cheap again, and everybody forgot about low-energy homes.
Where We Are Now
Fast-forward to the 21st century and suddenly energy is on the front page again. And again homes are responding to pressure to reduce energy usage, but in a curiously different way: through envelope and mechanical technologies.
The "envelope" of your home is its wrapper: The roof, walls, windows, and foundation. It's what keeps the outside out. There was a time when heat flowed rather freely through the envelope; windows were single-pane thickness and walls and roofs had little or no insulation.
Today, wall and roof assemblies can be very high-tech. New types of insulation, sheathing, and siding slow heat flow to a crawl. Infiltration barriers (Tyvek, Typar for example) stop excessive water vapor migration and seal the outside more tightly than ever. Houses can be sealed so tightly in fact, the trapped moisture can accelerate mold growth (that's a subject for another time).
Windows and doors have also gone light-years beyond the old wood-framed putty-glazed sashes of the early twentieth century. Windows today are offered with multiple panes of glass sealed together to create an insulating layer within; often that "airspace" is filled with inert Argon gas – which has a higher resistance to heat transmission than air.
The framing of the windows is far better sealed, and the installation methods are much improved. Even plain old glass isn't what it used to be – now it's coated with a microscopic layer that allows sunlight in, but blocks ultraviolet rays and keeps heat from escaping.
Other high-tech wall technologies include ICFs (Insulated Concrete Forms), and SIPs (Structural Insulated Panels).
The other area of big change is mechanical technology, including groundwater-source heating and cooling systems, active solar collection panels, and on-demand water heaters.
Furnaces, heat pumps, heat exchanges, boilers, and air conditioners are more efficient that ever and work hard to squeeze every BTU of energy out of the fuels they use. And sophisticated computer control systems manage the distribution of heat throughout the house.
Design for Energy Efficiency
Envelope technology and mechanical technology are two ways to make any house design more energy efficient. High-technology energy management systems can be added to any house design, and most can be easily modified to include the latest in envelope technology.
But envelope and mechanical technologies aren't the only way to create a more energy-efficient home. "Back in the day," we did it with old-fashioned good design – by paying attention to solar orientation, window quantity and location, and house shape and size.
Before you start your new home or remodeling design, give careful thought to how the design – not just the envelope and mechanicals - will impact its energy use.