By Andrew Hunt
Building green isn't in its infancy anymore. For more than 10 years, the residential construction industry has been implementing new designs, technologies and building methods that may someday lead to "zero energy" homes being the standard home design.
The "zero energy" house — a home that generates energy onsite with technology such as like photovoltaic cells or solar hot water panels — is still a rarity, but Betsy Pettit believes that the industry is on the right path. A registered architect with more than 25 years of experience in affordable housing and a project manager for Building Science Corporation's Building America project, Pettit has seen the trend of green building improve many aspects of energy efficiency in homes.
"I think there are some questions about how we are doing on the road to a zero-energy house right now," said Pettit. "We've done a very good job, in general in this country, about reducing [air] infiltration; we've done a good job getting the message across that more insulation is better, more efficient equipment is better and that lighting and appliances matter."
Pettit sees that the trend in green building is making a difference today as consumers become more aware of energy-saving options available and builders begin to market higher performing homes. To accelerate the pace towards zero energy homes, Pettit believes that there are 10 lessons to be learned from current building practices:
1. Build smaller houses. "The bad news is that we keep increasing our house sizes. If we take a house that is 2,280 square feet with all the improvements and compare it with a house that is 1,140 square feet, the smaller house will still use less energy. It's kind of a no-brainer, but the message here is that we need to encourage people to build smaller houses." Pettit believes that with a little effort, builders can educate homebuyers to use the space that they have with better design. Porches, breezeways and decks can extend living spaces without conditioning. Features like overhangs can contribute shade to the home, and better positioning of windows for breeze and sunlight will also help with utility bills and the comfort of the home.
2. Build tighter homes. "Air tightness is still the most important factor in energy efficiency," said Pettit. Heat loss can account for 37% of the home's energy use. Suggestions for reducing this loss include using better windows, increasing the amount of insulation in the home, and improving ventilation systems.
3. Ventilate. "There are literally hundreds ways to provide outside air to the home," said Pettit. By paying attention to how fresh air is introduced into the home Pettit believes it will not only help with heating bills, but will also make for a healthier living space for the occupants.
4. Use more insulation, and install it right. All insulation is good insulation, as long as it is installed correctly, Pettit said. Many builders today understand the importance of a well-insulated home and are starting to implement better practices to fill the voids in the home and make sure all surfaces are covered.
5. Control moisture. Keeping water moving down and away from the building envelope greatly contributes to the durability of a new home. Pettit stressed that using the appropriate moisture control system for the home and region is critical. This includes taking into account the depth of the local water table and providing exterior drainage for the home.
6. Design roofs that have a slope to the south. Even if today the homeowner doesn't want alternative energy sources such as photovoltaic cells or solar hot water panels, building the home so that it can easily incorporate new technologies is important.
7. Install the most efficient heating and cooling appliances and water heater the homeowner can afford. Power venting exhaust, using closed-combustion hot-water heaters, and installing instantaneous hot-water heaters are all improvements to be considered and readily available to the builder in today's market.
8. Use efficient lighting and appliances that meet homeowners' needs. "Refrigerators are one of those things like houses," Pettit said. "They just keep getting huge, but how big a refrigerator do you really need?" Proper sizing of household appliances can reduce the home's energy load significantly, and provide for a more comfortable living environment, as well as more floor space. Light-bulb selection is also important; compact florescent lamps will use about a third the power of incandescent bulbs.
9. Reduce home energy use by 40-70% before adding onsite energy sources like solar hot water panels or photovoltaic cells. "Because you don't know what we'll be using for heating and cooling in the next 50 or 100 years, create a great building envelope, if nothing else," said Pettit.
10. Commission all mechanical and onsite energy systems. After onsite energy sources are installed, it is important to monitor their effectiveness. By commissioning the systems to make sure they are performing as expected, builders can ensure that the house is as efficient as promised.
Though these lessons in home building may not result in a home that is completely "off the grid," by paying attention to the building construction, design and appliance selection, Pettit recognizes the positive impact they can have on new homes today. "We can reduce the energy need of a home by about 40% per year using these techniques."
Andrew Hunt is a Pittsburgh-based freelance writer who specializes in residential construction topics.
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