It shouldn’t be a surprise that energy would be a hit in Texas—but 8,000 people on the first weekend to tour a home that uses less than half that of a standard new home, and makes the rest itself? There is no magic in the technology and engineering, but clearly builder Jim and his systems thinking team have created something special at the Building America Zero Energy Home of Lone Star Ranch in Frisco, Texas.
At the first-of-its-kind Zero Energy Home in North Texas, energy-efficient technology and science are not thrown into and onto the home, but are integrated into every aspect of the home’s design, walls, and equipment. Early in the design process, decided to make it a Building America project, and became a Building Science Consortium partner. A full-day design charrette in Westford, Massachusetts, became the first step in ensuring that this Zero Energy Home would be a systems-engineered expression of age-old and cutting-edge architecture and building science.
The Building America/Building Science Consortium approach to Zero Energy Homes is based on this premise: A home that consumes no more energy than its renewable energy systems can produce must excel in all aspects of home performance. The complete high-performance home must address:
Let’s take a look at how the Building America Zero Energy Home of North Texas stacks up on complete home performance.
The key to any zero energy home is reducing the overall load as much as possible, keeping the renewable energy systems within the home’s ability to support both their cost and their typical rooftop location.
This means that all major systems in the house—the building enclosure, the mechanical systems (space heating/cooling/ventilation), domestic hot water, appliances, and lighting—must work together. As you look at the impressive list of energy features in this home (see sidebar on the right), keep these points in mind:
The lower heat exchanger is connected to the rooftop solar system, the upper to the tankless water heater. Since the closed-loop solar water system can “communicate” with the space heating system through the tankless water heater coil, the hot water storage tank takes on or gives up heat as solar supply and domestic water/space heating needs demand. The water heater is a backup supply for space and domestic water heating. This system depends on a series of controls for efficient operation, but is much less complex than many systems with the same level of integration.
As the home becomes a more and more efficient environmental separator (keeping the outdoors out, and the indoors in), maintaining indoor environmental quality becomes a greater challenge. This Building America Zero Energy Home has a mechanical ventilation system integrated into the central heating, ventilation, and air-conditioning (HVAC) system, and no-combustion or sealed-combustion mechanical systems. The builder and architect selected materials for their low emissions and designed assemblies for their ability to manage moisture and mold.
A high-performance home is a lasting home, and maintains its performance over time. There is no simpler nor more effective way to reduce the environmental footprint of a building than by making it last longer. Durability is a three-legged stool that requires due diligence in design, specification, and workmanship. The architect, the builder, and the trades must achieve durability in concert. The
Building America Zero Energy Home of North Texas will long stand as a testament to durability, with its ventilated claddings, engineered wall assemblies, and painstaking attention to moisture control details.
Fresh water is as critical as energy in nearly every region of the country, even in Frisco, Texas, which receives nearly 40 inches of rain a year. This home has a comprehensive water conservation package:
A home that supplies its own energy needs over the course of a year would mean little if the occupants are dissatisfied or uncomfortable. As an Environments For Living® Platinum home, its thermal comfort is guaranteed throughout the entire space. And the meaning of thermal comfort is extended to cover hot water, as the structured plumbing/on-demand recirculation system provides hot water at every point of use “instantaneously” (and wastes no more than a cup of water in the process).
The story of how the Building America North Texas Zero Energy Home team was built is too good not to tell.
But what does a “one-off,” nearly $1 million Zero Energy Parade Home really mean, in the grand scheme of things? Project manager Chris sees it this way:
“This home can help people make the right choices. They learn the cost and value of granite countertops and the master bath with whirlpool, as well as the high-efficiency appliances and solar water integrated heating. These are good things.”
For builder Jim, the proof is in the voting—his Building America North Texas Zero Energy Home was voted “Best House Overall.” “There are seven very beautiful homes here at the Parade, but the most popular one, the one everyone is asking so many detailed questions about, is this home. Performance pays,” says with a winning smile.
See the North Texas Zero Energy Home analysis on the Building Science Corporation Web site at www.buildingscience.com for more detailed information and discussion on the energy performance of this home.
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