Homes are increasingly being built in the United States to use little or no energy, a trend that could help reduce U.S. dependence on oil and gas, according to a new book.

David Johnston, one of the nation's leading experts on green building, co-authored a new book, Toward a Zero Energy Home. Courtesy of David Johnston

David Johnston, one of the nation’s leading experts on green building, co-authored a new book, Toward a Zero Energy Home.

“Zero energy homes are becoming the new green,” says David Johnston, one of the nation’s leading experts on green building and co-author of Toward A Zero Energy Home: A Complete Guide to Energy Self-Sufficiency at Home (Taunton Press.)

“The larger climate change becomes an issue, the faster zero energy homes will be demanded,” Johnston, founder of greenbuilding.com, tells Green House. He says buildings are responsible for 48% of U.S. carbon emissions, so making them more efficient could have a huge environmental impact. 

These homes produce as much energy as they use on an annual basis. They typically include renewable energy features such as solar panels or wind turbines. 

“Building a net zero house can get expensive, but it’s not necessarily so,” Johnston writes, noting how Habitat for Humanity built such a house near Denver for $116 a square foot. 

The key, he says, is a well-designed, super-insulated home that takes advantage of passive solar gain and is so efficient it needs very little power. He recommends builders make houses airtight and then use mechanical ventilation to circulate air. 

His book, like his prior Green From the Ground Up, also co-authored with freelance writer Scott Gibson, is an easy-to-understand yet comprehensive guide that includes plenty of pictures and a dozen interesting case studies. 

The featured homes, all built for zero energy living, range from bungalows to ranches in both rural and urban settings. 

More common than zero energy homes are “near zero” ones that don’t necessarily generate power but use dramatically less energy than conventional homes. 

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“There are scores of builders all over the United States and Canada who are constructing houses like these,” Johnston writes. 

He answered Green House questions about building new homes and retrofitting existing ones: 

Can homes really be so well-insulated they need almost no heat?  

Globally building codes are approaching that standard. It will be code in the U.K. by 2016, EU by 2018 and California by 2020. It is feasible and cost effective today with good design and careful attention to construction details. Habitat for Humanity built one in Denver and houses built in Tennessee use $1 a day for heating and cooling. 

Will geothermal systems get less costly and more common?  

If the insulation and the rest of the envelope are done right, geothermal systems at $20,000-50,000 will be superfluous. Only a small heating and cooling package will be required to provide comfort in all seasons. 

What kind of insulation and windows do you recommend? 

Most state-of-the-art homes use a spray foam first to seal all connections between wood components….All windows today should meet the new Energy Star standards. That means low-e coatings with a U-value of less than .30 to receive the tax credits and likely new rebates. There are new windows on the market that are more than twice as energy efficient. The entire Empire State Building was just retrofitted with them providing a three-year payback. 

If a homeowner has $5,000 to spend, what are the most cost-effective ways to boost an existing home’s energy efficiency?  

The first best dollar spent is to get an energy audit. It is like magic to see how air moves in and out of your home and with an infrared camera, you can actually see behind the drywall where the insulation is and where it has been left out. That should run $250-$400 for a complete analysis. 

The report will identify the best place to invest the other $4,600. Typically air sealing is the first place to start. Then add insulation to the attic. Next seal the crawlspace or basement and insulate the walls or under the floor above. Lighting with compact fluorescent bulbs is almost instant payback. Set back thermostats and plug strips for media centers and computer work stations. In most modest-sized homes, this can be done for under $5,000. 

General

• ZigBee Alliance

United States

• ENERGY STAR
• US Department of Energy’s “Your Home”
• US Department of Energy’s “”Energy Efficiency & Renewable Energy (EERE)”
• Renewable Energy Research Laboratory
• Institue for Energy Research
• US Senate Committee on Energy & Natural Resources
• Consumer Energy Tax Incentives
• IRS – Energy Incentives for Individuals in the American Recovery and Reinvestment Act (ARRA)
• Residential Energy Tax Credit (US IRS Form 5695 2009)
• DSIRE Database for State Incentives for Renewable’s & Efficiency
• IREC Interstate Renewable Energy Council 

Australia

• Energy Labeling Standards in Australia

 Canada

• Canada Energy Guide

United Kingdom

• Energy Saving Trust (UK Site)

Wind Links

• US DOE Wind Maps and Wind Resource Potential Estimates
• NREL National Renewable Energy Laboratory – Wind Maps
• Renewable Energy Atlas of the West
• Bergey Wind Maps

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