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Double Zero: Net Zero Energy with an Eye Toward Water Conservation

Posted by Hilary Daninhirsch

Sep 26, 2014 12:24:00 PM

KB HOME RECENTLY constructed a home in Lancaster, California (in Los Angeles County), which earned the company RESNET’s award for Lowest HERS Index Score for a Production Builder. Dubbed the Double ZeroHouse 2.0, it’s not only net-zero energy, it also requires no freshwater for irrigation. Even without the SunPower solar PV system, this home achieves an impressive HERS score of 42.

Jacob Atalla, vice president of Sustainability, says that KB Home was the first homebuilder to sign up with RESNET as a RESNET Energy Smart Builder. The company has its own Energy Performance Guide, incorporating HERS principles, which allows homeowners to calculate the dollars they can expect to spend and save.

Atalla reported that KB Home obtained a HERS rating for all 7,000 of their new homes in 2013, and achieved its goal of increasing their energy efficiency by 3 percent. The average HERS score for homes built in 2013 was 65.

“On average, homeowners currently save $1,000 per year on energy bills compared to a typical resale home,” he says. “It’s a big value, and customers are looking for it.”

In fact, the HERS Index score is being added to many MLS listings; a home that has a very good (low) score gains an advantage over one that doesn’t, even if the homes share many other characteristics.

KB Home builds in communities across the country, from California to Florida to Maryland. The company chose to build the Double ZeroHouse 2.0 in Lancaster because the city strongly supports renewable energy. The high desert, drought-prone location also allowed KB Home to showcase their water conservation mechanism -  a new graywater recycling system from Nexus eWater. The system can treat up to 40,000 gallons of water a year for use as landscaping irrigation.

“We also used brand new technology—new to us—that contributed to lowering the HERS score in that house,” says Atalla. The Power-Pipe by RenewABILITY is a wastewater heat recovery device that takes wastewater from the shower drains, extracts the heat, then uses it to heat the new freshwater going into the tankless water heater. Atalla estimates the Power-Pipe saves approximately 10 percent of the energy spent on water heating.

As with all of their homes, KB Home focused on the building’s envelope and mechanics. The team insulated the attic at the roof deck, upgraded insulation in the walls, tightened air sealing of the house, upgraded windows to argon-filled units and installed a tankless water heater. Another “extra” was a smart garage with an electric vehicle charging station.

Atalla says that RESNET-certified HERS raters are usually on site twice—once during the framing and installation of insulation and then again at the end of construction. But because they were aiming for “double zero,” the rater partnered with KB Home early in the design process, helping to identify elements that could make the home more efficient and meet the net-zero-energy target, and visited the site more frequently, as well.


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Falling Solar Prices Make Net Positive Energy Building Easier

Posted by Zack Semke, Guest Columnist

Aug 11, 2014 7:57:00 AM

Our planet is heating up, and humans are the cause: 97% of climate research conducted over the past 20 years concurs. So anthropogenic global warming is real. But it’s one of those problems that feels so big that it can paralyze.

After all, the potential effects are biblical in their scale. And the conventional wisdom is that it’s a really hard problem to address, with lots of cultural, political and economic reasons for inaction. But amidst the hand-wringing and hemming-and-hawing a new possibility is beginning to emerge. It may be less painful to reduce greenhouse gas emissions than we thought.

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Green Builder Research: Sustainable Upgrades

Posted by Craig Coale

Jun 5, 2014 10:54:00 AM

Green Builder Media’s data shows that Energy-Star appliances, high-efficiency HVAC and water conservation plumbing fixtures are the top three sustainable products that are standard in new homes.


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A Net Zero Future: Market Trends and Building Science

Posted by Sara Gutterman

May 15, 2014 10:47:00 AM

I recently attended the ‘Race to Zero’ student design competition hosted by the Department of Energy (DOE) at the National Renewable Energy Laboratory in Golden, Colorado.

The competition challenged student groups from universities across the US and Canada to design zero energy homes. Awards were offered for sustainable design, effective technical integration, and cost effectiveness. As is usually the case with such competitions, the students displayed impressive imagination, contagious curiosity, and encouraging enthusiasm.

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The Energy-Water Nexus

Posted by Sara Gutterman

Mar 20, 2014 9:51:00 AM

Green Builder Media President Ron Jones has an ominous prediction: “If you think the oil wars are bad, wait until the water wars begin.” With severe drought conditions expanding across the globe, I fear that his warning may become a reality sooner, and more acutely, than we think.           

In this country, California, Texas, Arizona, and Georgia are on the frontline of the water crisis. Arizona just experienced its fourth warmest winter to date, causing water shortages across the state, and Texas is suffering through the lowest reservoir levels in 25 years.

After years of record water shortages (and several instances of narrowly dodging substantial inter-state litigation with its neighbors), Georgia is making major investments in upgrading its water infrastructure and has made a state-wide commitment to efficient and sustainable water use for agricultural applications, electricity generation, golf course irrigation, landscaping, as well as industrial, commercial, and domestic use.

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VIDEO: Alliance to Save Energy

Posted by Green Builder Staff

Feb 21, 2013 12:13:00 PM

This video showcases a net-zero commercial building. The Research Support Facility on the National Renewable Energy Lab's Colorado campus is a true example of energy productivity!

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Target: Suburbia

Posted by GBM Research

Oct 30, 2012 3:55:00 PM

THE NATIONAL INSTITUTE IF STANDARDS AND TECHNOLOGY (NIST) has taken on a project of major significance--demonstrating that a typical American home in the suburbs can be built to net-zero standards. In other words, it will look and perform just like a "normal" house, but will produce as much energy as it consumes over the course of a year.

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Market Ready Modular Housing

Posted by Tux Turkel

Oct 31, 2011 12:07:00 PM

CAN SPENDING LESS ADD UP TO ZERO? Builders have learned that if they have big enough budgets, it’s not hard to create custom homes that produce as much energy as they consume over a year.
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A Military First: Net-Zero Homes

Posted by Green Builder Staff

Oct 26, 2010 12:59:00 PM

CAMPBELL CROSSING, THE PUBLIC-PRIVATE PARTNERSHIP between Actus Lend Lease (Actus) and the U.S. Army, today announced the completion of the first two zero-energy homes on a military installation. A design approach focused on energy efficiency and solar thermal energy production will result in a home that can function on 54% less energy than a home of comparable size constructed using today’s building standards.

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