ZERO ENERGY HOMES (ZEH) AND THE GREEN CONSTRUCTION PROCESS
The Luxury and Elegance Within:
For a glimpse of the houses of tomorrow, look no further than the work of a forward-thinking production builder Green Homes Midwest. Combining solar energy technologies with energy-efficient features and energy-saving construction techniques, Green Homes Midwest is constructing houses that generate as much (or possibly more) electricity as they consume on an annual basis.
The houses, developed under the U.S. Department of Energy’s (DOE) Building America research program, act as miniature power plants. As a result, the estimated total annual energy cost for houses in the Zero-Energy Home (ZEH) program is approximately 60-100 percent less than that of similar houses. DOE’s goal is widespread adoption of these and additional features by 2020 in order that a large number of new U.S. houses will be true net-zero-energy homes. With over 500 ZEH program houses in nine communities in California, our firm, Green Homes Midwest is just beginning to work toward the DOE’s goal. (Access www.buildingamerica.gov for more information.)
California was a good testing ground for building ZEHs with renewable energy technology — a “grand experiment” that is beginning to pay off. California has the combination of opportunities and incentives that make ZEH communities affordable and marketable: utility “buy-down” programs that subsidize solar technology purchase; net metering, allowing the homeowner to sell unused energy to the utility company and “bank” excess energy credit to offset their usage when the solar system is not generating energy; and, of course, abundant sunshine. The marketability of this package is promising, and proponents hope to replicate California’s success in other areas of the country. Illinois is already moving toward implementing similar building methods.
Constructing The Zero-Energy Home
A key element in designing a ZEH is that the houses overall energy use first must be dramatically reduced through a combination of super-efficient features and advanced construction practices. The use of these energy-saving building methods ensures that the addition of a relatively small photovoltaic (PV) solar system (typically 3 - 4 kilowatts in capacity) can effectively lower the electricity usage of a house by half or more compared to a typical new home.
For instance, a typical house has ways to “tighten up” residential energy consumption including: improved ceiling and wall insulation, energy-efficient appliances and the use of fluorescent lighting. All of these efforts are combined in a whole-house approach to designing and building the ZEH
Once a house has been made super energy efficient, an array of PV Roof Shingles is installed. The array converts sunlight into direct current electricity, and through the use of an inverter, turns DC into AC electricity to power the house. For multiple reasons, mainly aesthetics and to minimize roof penetrations, BIPV (builder integrated photovoltaic) systems are a good choice for your home.
Zero Energy Homes Walls
Our Zero Energy Green Homes will use the Techbuilt wall system.
There are two unmistakable trends in the home building industry. First,
dimensional lumber is losing its place as the dominant structural material.
Second, manufactured components are steadily replacing site-built ones. Soon,
panelized walls will leap to greater importance. Techbuilt Manufacturing, Inc.
is well-positioned for both trends.
Their ThermoTech 21 engineered panels
feature 18 ga. steel tubes for strength and expanded polystyrene (EPS) foam for
insulation. Wall panels are 7-1/4 in. thick (R-30) and roof panels are 11-1/2
in. thick (R-50). EPS foam is ozone-safe, because it uses air for a blowing
agent.
The panels are made by first routing channels for the 1x2 steel
tubes. They are placed on opposite sides of the panel every 24-in. Each tube is
connected to its mate with a long screw. Foam separates the opposing steel
tubes, preventing thermal bridging. In the wall panel, 5-1/4 in. separates the
tubes. Four steel angles placed on the top and bottom edges join the steel
tubes. These angles can span the ends of adjacent panels to lock them together.
Panels can be up 32 ft. long.
A 20 ga. steel angle wraps each corner, and
fastens to the tubes. Siding screws directly to the tubes. Window and door
openings are built into the panels and wrapped with 2x8 lumber. Roof panels sit
on a ridge beam, so the entire upstairs has cathedral ceilings.
The wall
panels can be used below grade, too. The panels sit on a standard footing.
Treated plywood is attached to the panel and then covered with
waterproofing.
With R-30 walls and R-50 roofs, the heating load is about 25 to 30 percent of
a wood-framed house, so low that a high-recovery water heater satisfies all
water heating and space heating needs. A wiring chase is preformed into the wall
panels and electrical boxes attach to the steel tubes. The manufacturer
recommends that plumbing be located in interior partitions or in specially-built
plumbing chases.
The building system includes a unique feature:
minimalist rim joists. Only the top chord of the metal-web floor truss bears on
the outside walls. The lower chord hangs entirely inside the panel walls.
Instead of a 10- to 12-in. rim joist, the comparable area in the ThermoTech wall
is only 1-1/2-in.
According to the manufacturer, component cost is 5
percent more than typical wood-framed construction. Like other panelized
systems, higher material cost can be more than offset by lower labor cost. The
panels carry a 10-year limited warranty. For further details, please see www.techbuilt.com
Roof Shingles
Green Homes Midwest uses SOLARSAVE® Roof Shingles which are a unique product that enables you to maintain the natural look of your property while generating clean, safe, efficient electricity from the sun.
Features & Benefits
- Easily installed using Roofing Tile Institute standards
- Robust, weatherproof, fire-rated, fully warranted
- Edge profiles naturally shed water
- Durable low voltage system is safer to install and maintain
- Modular, expandable system can be energy customized
- Snow load capacity over 200 pounds per square foot
- Wind load rating up to 125 mph with clips installed
- Class A Fire rated
- CSA certified; UL1703 listed; Class II 600VDC
- 25-year warranty to produce 80% power output
- Inverter had very high conversion ratio of AC to DC
- Comes in different colors; black, red & brown
Creating A Market
Why Does Green Homes Midwest Build A ZEH?
A big motivation is that building environmentally friendly is the right thing to do for the environment. Solar energy’s lack of noxious emissions and ability to reduce a house’s reliance on foreign and domestic fossil fuels reap tangible benefits — and for Green Homes Midwest, provides a marketing edge. The main reason is market differentiation; the ability to offer a house with basically no energy bills is a distinct advantage with new-home buyers. Green Homes Midwest will build a ZEH model to show you how a ZEH has as beautiful of an interior as a non-ZEH and then build your ZEH to your desire of luxuries and size as well as location.
The greatest benefit of the ZEH concept for a buyer is the most obvious — dramatically reduced electricity bills over the life of the house. Depending on energy usage, family size and square footage of the house, the ZEH owner can conservatively expect to save anywhere from $1,200-$4000 per year (depending on your states utility prices and usage). This payback will provide positive cash flow immediately. ZEH owners also are largely immune to utility rate hikes. Let’s not forget a 1% discount on Green Mortgage
A recent survey conducted by the Davis Energy Group found that 67 percent of recent homebuyers likely would have paid $8,000 more for their new house if it simply generated only 40 percent of its own electricity (our ZEH‘s should generate close to 100%). Most consumers embrace the idea of harnessing the sun for renewable, reliable energy. But most consumers are unaware that the Zero Energy Home program even exists. The DOE’s Building America program has a budget for R&D, but not for marketing and outreach efforts. Green Homes Midwest is dedicated to educating consumers and suppliers that we have the means to produce reliable power for an entire house while minimizing harmful greenhouse gases and dependence on foreign, volatile sources of raw materials.
The Utility Company Pays You
As an example, in the case of Harmony Heights (ZEH project in Tennessee), the sun translates not into flowers or food, but into direct financial return: The homes have rooftop solar electric collectors that create electricity whenever the sun is shining. When resident of one of the ZEHs Becky Clark received her first electricity bill there, it showed a credit of $35 in one month. “We got paid!” she says, beaming. “It’s like we’re our own little power plant.” At her old apartment, Clark paid nearly $200 per month for her combined utilities .
Price signals are a good way to change consumer behavior: “We’re working with utilities on ways to give consumers good indications of time-of-use-pricing.” It’s much more expensive for consumers to use electricity at peak load times which occur during the work day when businesses are buzzing, air conditioners are humming and energy demand is at its highest.
“We’re trying to come up with user-friendly meters that could go in every home so consumers could have a real-time read-out of the cost of their electricity use,” Even better, appliances and heating and cooling systems should be computerized (as are with Green Homes Midwest) with “smart economizers,” so that they automatically run at optimum times of the day to keep electricity costs down.
The Zero-Energy Revolution
Why, you may wonder, would utility companies have any interest in cooperating with zero-energy home programs, thereby encouraging consumers to use less of their product? Because the demand for electricity over the past decade has grown faster than the utilities’ capacity to produce it. That situation was dramatically illustrated by the August 2003 blackout: The largest ever in North America, it affected 50 million people in eight states and southeastern Canada.
It’s very expensive for utilities to invest in greater
transmission line capacity to carry the growing electricity loads; In
addition, it’s becoming increasingly difficult, especially in
condensed urban areas, to find sites for new substations and
transformers to generate extra capacity. So, investing in on-site
generation that goes directly into the home without all that
infrastructure makes good economic sense. Rooftop solar collectors
produce power during the afternoon and along with other features of
these homes, such as continuous fresh-air ventilation and
high-efficiency control systems , help reduce the utilities’ peak
demand.
