Sopris Homes: Raising the Bar on Green Building
When John Stevens, president and CEO of Sopris Homes in Boulder, built his home according to Energy Star standards, he was disappointed with the results – especially performance and comfort. He then set out to change the way Sopris builds homes, and arrived at a “whole house” or “systems” design approach, in which all the home’s systems, together with high-quality craftsmanship, work optimally to insure high performance and comfort.
Stevens partnered with Environments for Living™ (EFL), which requires the builder to meet specific building standards designed to result in homes that are safer and more energy efficient, comfortable and durable than conventionally built homes. For builders who meet these tough standards, and the buyers of their homes, EFL offers a comfort and energy usage guarantee.
Sopris Homes, building since 1994, became the first builder in Colorado to guarantee both comfort and energy use on all its homes.
High-performance homes
Besides systems-engineered whole house design and quality-controlled construction, a high-performance home relies on performance testing to assure that the home is healthy, comfortable, affordable, energy efficient, durable and environmentally responsible.
Sopris homes are built for high performance. Tighter construction methods reduce energy loss from the home. Every exterior wall is insulated with blown-in insulation for a superior thermal envelope. HVAC systems use high-efficiency furnaces and air conditioning, with multi-zone heating and cooling that allows you to control each level of your home independently. High-efficiency furnaces exceed 90 percent efficiency. Fixed and casement windows have an airtight seal. Low-E coatings provide superior comfort and reduce the size of furnaces and air-conditioners. Sopris’ mechanical ventilation system supplies fresh filtered air for indoor air quality. Custom ductwork is engineered for each home, and all heating and cooling is done through ducts rather than building cavities; ducts are sealed and then tested for tightness. For durability and mold prevention, drainage planes are installed on the exterior walls to avoid water infiltration, and the home is covered with a layer of waterproof material.
Environments for Living™ (EFL)
EFL requires strict performance testing of each Sopris home. Confidence in the builder’s engineering, materials and workmanship allows EFL to guarantee that the temperature in Sopris homes will not vary more than three degrees between rooms in the same heating zone, and the energy used to heat and cool the home will not exceed a guaranteed usage.
David Bell, director of building science for EFL, works with builders like Sopris Homes to build performance-based homes. “I give them performance specifications they must meet, and training for their subcontractors to implement our program. We take a systems approach; the builder must implement seven items necessary to build a high-performance home – how the home performs in terms of comfort and efficiency. Each home is rated by a third party using the HERS rating.”
The seven key areas the EFL program addresses are: tight construction, fresh air ventilation, improved thermal systems, right-sized HVAC systems, air pressure balancing, internal moisture management, and combustion safety.
EFL also provides each homeowner with a manual, explaining how EFL homes differ from conventionally built homes, and the “science” behind key features like the home’s thermal envelope.
Bell adds: “The fact that Sopris is participating in the program, and the things they are doing, are a testament to their commitment to build a quality house. The homeowner should enjoy comfort [for] years.”
HERS testing
Robby Schwarz, of Energy Logic, does all the performance testing for Sopris Homes. “We quantify the energy performance of houses for Sopris,” he says. “We do quality control, energy code compliance, and program compliance for Energy Star and EFL. With the HERS index scoring system, the lower the score, the better…100 is equal to a new, code-built home; 0 means it uses as much energy as it generates.” The maximum score Sopris will accept is 69 to 70, which means it is 31 percent more efficient than a new home built to standard code.
To earn the Energy Star label, a home must meet guidelines for energy efficiency set by the U.S. Environmental Protection Agency (EPA). “Sopris has been very consistent in meeting the standards of Energy Star and EFL,” Schwarz says.
Energy Star calculates estimated energy savings from a menu of options. EFL goes further – designing a whole house approach to ensure that energy saving features complement each other to achieve the desired effect when they performance test every home, so they can offer an energy-use guarantee. They also inspect to be sure these items were installed correctly during construction. They tell how much energy is being used to heat and cool the house. This can be related to a dollar amount to judge whether the home’s energy bills will be lower.
Energy Logic uses a four-step process: They look at the house plan and build a computer model of the house. From that they can estimate and quantify whether it will meet the energy code and Sopris’ internal requirements, and they can make recommendations. Next, in three onsite visits, they do a duct-leakage test to determine how airtight it is and how well it will do in delivering energy to the house; that the insulation has been installed correctly, checking the air barriers, windows, ventilation systems, and more; and, a week before the house closes, performance testing and giving an analysis.
“The best comparison is to standard new-home construction,” Schwarz says. “Sopris does a tremendous job exceeding standard new-home construction that meets both Energy Star and EFL [requirements]. They stand behind it by offering energy-use guarantees.”
Net-zero energy-use homes
Sopris Homes designs and builds near-zero and net-zero energy homes, too. If you begin with a Sopris Home that meets EFL standards, you already have the most efficient structure and materials in your home. The next step is adding solar and geothermal.
A Sopris home near Boulder, built for near-zero energy-use, has turned out to be a zero energy home. This 6,624-square-foot high-performance solar and geothermal home pays no energy bills. After living in the house for a year, the owner was producing more energy than he was using.
“We’re currently building another home near Boulder that may also be zero-energy, and we have another in the design stage that will have a passive solar greenhouse to collect heat and distribute it to other parts of the house,” says John Stevens.
“We’ve been studying and implementing EFL energy-efficient building practices since 1999. We’ve got the foundations for energy efficiency in the design and construction of the house’s thermal envelope. The less energy the house requires [because it is well built], the less energy you have to produce on site. The more energy that is produced on site, the closer to zero the energy use will be. The zero-energy home can include photovoltaic (solar) for electricity, and geothermal for heating, cooling, and domestic hot water.”
Geothermal heating is one of the most efficient ways to heat and cool a home, by tapping the relatively constant temperature of the earth. It uses less energy than conventional heating or cooling systems, which translates into savings on utility bills.
Dan Rau, president of Colorado Geothermal Drilling, which designs and installs geothermal systems in homes, works closely with HVAC contractors. Almost two years ago Rau installed a system on the first Sopris net-zero home. “There is very little maintenance on a geothermal system,” he says. “You just change the air filter. The operational cost is lower than a standard conventional natural gas heating system. Installing geothermal is an added expense the owner does upfront on a new home or on a retrofit. It pays for itself.”
He points out, “The way Sopris is going about building a home, they take the whole house into consideration. The better they build that building envelope, adding extra insulation, and the construction they do, the less it costs to install and to operate a geothermal system.”
Educated Homebuyers
How much do homebuyers know about the importance of choosing a high-performance home – one that is built on sustainable systems that deliver net-zero or near-net-zero efficiencies that reduce the costs of ownership and lessen a home’s lifetime carbon and materials footprint?
Robby Schwarz comments: “I find it interesting that people know more about the technology of their cell phone or their car than they do about the biggest investment they make: their home. Comfort, durability, safety and efficiency: Builders like Sopris are building these into their houses, and homebuyers should bring these into their buying decision.”
For more information about Sopris Homes, call 303.527.0000 and visit www.soprishomes.com.
By Judy Finman for At Home
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