BUILDER's Concept Home 2011

Architecture can be traditional without feeling stuffy or pompous. The GreenHouse shows how. Designed in the spirit of Martha Stewart’s personal residence in Bedford, N.Y., it’s tasteful yet simple, with clean lines and plenty of connections to the outdoors. Large windows, 9-foot-4-inch-tall ceilings, crisp crown molding, and painted wood paneling make the interiors feel luxe and substantial, even if they aren’t big. And the plan isn’t overly prescriptive, so homeowners can choose how they wish to furnish and use its spaces.

“I like a home to be suffused in natural light and airy, with a generous amount of open space,” says the legendary founder of Martha Stewart Living Omnimedia and leading authority on all things domestic. Delivering on that vision, the heart of the home is a large entertainment area that blends dining room, great room, kitchen, and patio into a succession of fluid spaces.

But beauty is only part of the story. Placing functionality on par with aesthetics, the plan is also big on multitasking. Its flexible den can double as a home office, playroom, media room, or extra bedroom. A kitchen workstation provides a great spot for homework or paying bills, but is also command central for the home’s energy monitoring system, a Web-based tool that allows homeowners to track their electric, water, and propane consumption, as well as solar energy production.

And yet the GreenHouse makes a few unorthodox moves that run counter to the current conventional wisdom about building smaller. For example, it keeps its formal dining room (a space that’s been value-engineered out of many of today’s smaller homes) and allocates a larger-than-average share of square footage to storage. Built-ins are pervasive, the secondary bedrooms have walk-in closets, and the master suite assigns almost as much space to its dressing area as it does to the master bath.

This isn’t complete folly. Setting aside square footage for storage actually results in rooms that feel larger, Stewart says, because they aren’t cluttered with armoires and other bulky case goods. “The dressing area off the master bedroom has built-in cabinets and drawers to create storage space for clothing. That eliminates the need for dressers in the bedroom,” she points out.

But the most unconventional aspect of this home, by far, is its value proposition. Aptly named, the GreenHouse is testing the premise that next-generation home buyers will be willing to spend a little more up front on green stuff if the payoff is lower long-term maintenance and utility costs. Unlike the commodity dwellings of the housing boom, this residence isn’t destined for a life of flipping. It’s more akin to a well-made Swiss watch, which comes with a slightly higher price tag, but lasts a lifetime.

Builders who believe that achieving net zero means higher material costs can feel validated in knowing they are correct. KB Home estimates the cost of greening this house at $70,000—roughly $60,000 of which can be attributed to its solar energy features (the other $10,000 went to HVAC upgrades and high-efficiency lighting and windows).

But those who assume that green building means throwing all of your established subcontractor relationships out the window may be interested in this little insight: “We did use specialists for the solar thermal and photovoltaic installations,” says Dan Bridleman, vice president of national purchasing and contracts for KB Home, which currently ranks as the nation’s fifth largest builder. “But otherwise we relied completely on our existing trade base to get this house built.” (See “Green in Balance,” page 7, for a detailed rundown of the home’s net-zero process and formula.)

Is this a glimpse into production housing’s future? George Glance, president of KB Home’s Central Florida division, likes to think so. “This house is mainstream and something buyers can relate to,” he says. “It’s a functional, right-sized floor plan that is very livable and finely appointed. At the same time, it’s a very advanced house. If you have a million dollar budget that’s one thing, but when you’re operating with a sales price of $380,000, you really have to be efficient without compromising the function or finish of the home.”

Project KB Home GreenHouse: An Idea Home Created With Martha Stewart

Location Windermere, Fla.

Builder KB Home, Orlando, Fla.

Architect KB Home Architecture, Los Angeles

Designer Martha Stewart Living Omnimedia, New York

Size 2,667 square feet

Lot size 70 x 120 feet

Cost per square foot about $140

Anticipated sale price $380,000

Added hard costs for green attributes $70,000

Increase in monthly mortgage payment to cover the green extras $350

Average monthly electric bill for conventional Orlando home $250-$350 per month

Average monthly electric bill for the GreenHouse $0

Certifications LEED for Homes-Platinum, Environments for Living Certified Green, EPA WaterSense, EPA Energy Star, IAPMO Green Plumbing Code

HERS rating 0

Construction cycle 90 days

Green in Balance

If you’ve seen one net zero–energy home, you haven’t seen them all. There are many different ways to craft a house that produces as much energy as it uses. It all boils down to strategy in the face of certain “givens,” such as location, climate, site conditions, budget, and available materials. The art and science is in the tweaking.

KB Home used energy modeling software to piece together the biggest green elements and gauge how they affected each other. “You have to look at this whole thing as a series of systems contributing to an end result,” explains KB Home vice president Dan Bridleman. “You can’t ever put your finger on this one thing that did it. Net zero is almost always accomplished through a combination of techniques.” Let it be noted that this combination rated LEED for Homes Platinum and qualified for Environments for Living Certified Green, EPA WaterSense, Energy Star, and IAPMO Green Plumbing certifications. Here’s how the GreenHouse got to zero and is doing its part to help the environment:

The Envelope

Any net zero endeavor must start with conservation—the logic being that saving energy is cheaper than producing it. In Florida’s hot and often muggy climate, conservation starts with an air-tight shell. Structurally, the Greenhouse is comprised of exterior cement block walls lined with a layer of ¾-inch-thick rigid insulation and interior framing with FSC-certified wood. The critical piece is a sealed attic, which ensures the HVAC system isn't forced to work harder than it has to. “We sprayed the roof deck with foam insulation, and on the roof we used Monier’s cool roof tile, which reflects the thermal properties of the sun,” Bridleman explains. As a result, the attic maintains a constant temperature within five to seven degrees of the rest of the house, even though it’s not conditioned space.

Air Handling

Heat and moisture are friends to mold, but not in this house. An energy recovery ventilator in the attic recaptures as much as 80 percent of conditioned temperatures that would otherwise be lost through exhaust airflows and transfers that energy to incoming fresh air. This unit, combined with a whole-house dehumidification system, reduces the home’s cooling loads by not allowing them to escalate in the first place.

Then there’s the HVAC itself. “HVAC sizing is the biggest deal in the energy modeling equation because there are all kinds of things that can affect your energy usage, from heat-emitting light fixtures to appliances to vent fans in bathrooms, to people opening and closing exterior doors,” notes Chad Burlingame, director of purchasing and design for KB Home’s Orlando, Fla., division. All of those little details play into right-sizing an HVAC system that works efficiently and doesn’t provide more capacity than necessary. A conventionally built house of this size in Florida normally requires a five-ton HVAC system. This home lives comfortably with a two-ton, 19.5 SEER heat pump.

Building Components

Want to reduce construction waste? Don’t generate it in the first place. “Waste reduction starts with an accurate take-off so you are sending only what’s needed to the jobsite,” says George Glance, KB Home’s Central Florida division president. Building blocks in this home include pre-engineered trusses, floors, and panelized wall systems that reduce scrap lumber on site. Drywall and trim pieces left over during construction were recycled. With this approach, Glance estimates that the GreenHouse diverted 88 percent of the jobsite waste that a conventional home would normally send to the landfill.

Water Usage

The average American household wastes more than 3,650 gallons of water each year while waiting for hot water to reach the tap, according to EPA estimates, and 10 percent to 15 percent of energy use in hot water systems is wasted in distribution losses. Not so in the GreenHouse, which runs on an on-demand hot water recirculation system in lieu of a traditional boiler. Water heated by rooftop solar panels is stored in an 80-gallon thermal tank and then circulated through a loop under the slab. Each plumbing run off of the main loop is less than 10 feet long. This configuration reduces the amount of piping needed, and there’s no waiting for a hot shower. Instant hot water is activated with the push of a button in the kitchen, while motion sensors trigger it automatically in faucets and showerheads whenever someone enters the bathroom.

There are other water-wise features to boot. Wet areas inside the home are outfitted with low-flow faucets and dual-flush toilets. Outside, rainwater collection tanks store runoff from downspouts and redistribute that water into the landscaping. Sink and shower water is also filtered and redistributed for irrigation. A WeatherSmart irrigation system assesses the amount of moisture in the soil and turns on the sprinkler systems only as needed.

Electricity

Roof-mounted photovoltaics (PV) were introduced only after all of the other building and product specs were in place to ensure maximum performance on the conservation side. “Raised panels would have been more efficient, but they are also more conspicuous, and sometimes you have to make aesthetic choices,” Bridleman says. “We ended up choosing a flat panel PV system which isn’t quite as efficient, but it looks better on the house.” The 8.57 kilowatt roof system is expected to generate about 10,000 kW of electricity annually—enough to match the home’s anticipated energy consumption, which includes an electric car charging station in the garage. Although the PV system added an extra $60,000 in hard costs, the homeowner is eligible for a 30 percent federal tax credit as a result.

Homeowner Education

The final variable in any net-zero equation is consumer behavior. The GreenHouse is equipped with a simple energy monitoring system that allows homeowners to keep an eye on their electric, water, and gas consumption/production, tracking their usage history by the day, hour, week, or month, by peak usage times, and by dollar amounts. “The system even makes suggestions,” Bridleman says. “For example, during peak usage it can tell you how to adjust things like lighting controls or the condensing units in your fridge to save energy. You can access the system from home or via an application on your smart phone.”

For a virtual tour of the Builder Concept Home 2011, visit www.builderconcepthome2011.com.