Design in a Time of Uncertainty
By Rives Taylor, Principal, Global Resilience Research Lead
Last June, HARC Newsletter outlined some of the diverse energy-saving, pollution-reducing projects that HARC partners as a de facto sustainability advisor to the city of Houston.
One project that received only a brief mention then was the city’s 5-Star Energy Program, in which seven builders have been contracted to construct affordable, “ultra-efficient” homes in older, central-city neighborhoods.
The 5-Star program got underway in 2010 with economic stimulus funding from the American Recovery and Reinvestment Act. With 53 new, single-family houses completed through January and a goal of 61 finished houses by the initiative’s scheduled end in September, it’s an appropriate time to take a closer look at the effort.
“5-Star is unique in the way it incentivizes builders to upgrade new housing to reach ultra-efficiency levels well above Energy Star,” a key federal program that promotes energy-efficient products and practices, said David Hitchcock, the member of HARC’s research staff who has directed the management of the 5-Star program.
“Larger incentives have been provided to motivate builders to reach higher efficiency levels, with those homes receiving the 5-Star rating receiving the largest incentive,” Hitchcock said. “Most of the energy savings in achieving these ultra-high efficiency levels have been obtained through installation of solar panels.”
The 5-Star program is a notable element in the package of building-energy strategies that Houston undertook in response to the 2009 stimulus act. At the same time, it represents an expansion and enhancement of a local house-building program that already existed.
In a 2010 progress report, city officials described this existing program, a component of the Houston HOPE program, as an “effort to revitalize blighted but historic neighborhoods by creating new affordable homes in areas with high concentrations of abandoned lots.”
Though close to major employment centers, the report added, “the areas have suffered from poor physical infrastructure, crime and struggling public schools. Few homes were built in decades.”
Partnering with a local government authority, the city acquired tax-delinquent properties for redevelopment through Houston HOPE. Six private homebuilders and one non-profit organization, Houston Habitat for Humanity, in turn acquired sites for new, affordable, single-family homes, which have been upgraded for much greater energy efficiency under the 5-Star program.
The communities where 5-Star houses have been built are Trinity Gardens in Northeast Houston; Near Northside, immediately north of downtown; Sunnyside in South Central Houston, and Acres Homes in Northwest Houston.
In its role as manager of the program, HARC has worked with homebuilders and with an independent contractor’s energy-efficiency “raters,” who have assessed the builders’ efficiency upgrades to verify that homes indeed meet 5-Star requirements.
5-Star uses a yardstick called HERS, which stands for Home Energy Rating System and was established in 2006 by a professional association of energy raters.
Computer programs are used to determine a home’s rating. Lower scores on the HERS Index are awarded to more efficient homes. A rating of 100 represents the overall efficiency level of a standard new home. Most existing homes are less efficient and would receive higher ratings above 100.
Moving downward on the index – in the direction of lower and lower levels of energy consumption – a rating of 85 represents the efficiency of a home that qualifies for an Energy Star efficiency designation. Homes built and rated under the 5-Star effort in Houston had to have a rating of 60 to qualify. Further upgrades brought 5-Star homes to “ultra-efficient” levels – typically earning ratings in the 20s, with some in the teens and even one home so far at 5. Homes can be rated less than zero on the index if they produce more energy – typically with rooftop solar panels – than they’re using.
The program proved to be a learning process for participating contractors.
“Builders were increasingly able to improve energy benefits in 5-Star homes as they realized the advantage of the incentives,” Hitchcock said.
“The 5-Star program began with a broad goal of producing energy-efficient, solar homes in target neighborhoods,” he added. “This required numerous changes and adaptations in response to market conditions, home buyers and builder needs.”
Besides solar installations, other areas where builders attained greater efficiency have included water heating, attic insulation, duct placement and selection of appliances.
Receiving a rating of five stars (20-0 on the HERS index) has earned a builder incentive of $50,000. The smallest incentive (for a one-star HERS rating of 45-36) was $25,000.
For builders, the 5-Star program has offered other potential benefits, including experience in green-building technologies, an increased marketing profile for such expertise, and homes projected to sell faster than comparably-priced models without the same efficiency features.
The initial and continuing potential benefit for buyers is obvious – lower energy costs – though an ultra-efficient HERS rating, in itself, doesn’t guarantee that. Occupants’ energy-use behavior can greatly affect energy use, too.
Still, the potential economic benefit for homeowners is considerable, as is the potential benefit for environmental improvement.
For the houses built to date, the total annual energy savings that are possible for residents, thanks to the various efficiency upgrades, is estimated at about $2,100 each compared with a conventional house.
For all those houses combined, the annual reduction in emissions of climate-changing carbon dioxide from power plants is estimated at about 368 tons.