SOLAR TODAY - January/February 2010

The Grahams, a family of four, lived in a 2,000-square-foot, 1970 ranch house in a hillside neighborhood in Boulder, Colo. The house felt drafty in winter and hot in summer, with high energy bills. The solution, in 2006, was to plan a 700-square-foot expansion to the southwest, including a new dining room, playroom and home office. At the same time, the original house would get a “deep energy” upgrade, slashing heating energy by 50 percent and net annual elec- tric power use by 100 percent — or more. John and Vicky Graham hired our firm, Ecofutures Inc. (eco futuresbuilding.com), to assist with design and then execute the xpansion and retrofit on sustainable principles. We had recently finished building Solar Harvest, one of the world’s first monitored and verified zero-net-energy, all-electric custom homes in a cold climate. We’d completed more than 100 energy-efficiency upgrade projects and were involved in developing the REGREEN Residential Remodeling Guidelines ( regreenprogram.org). We planned to use the Graham home as the case study in deep energy retrofits for the merging guidelines document. One goal of the retrofit was to go beyond zero net energy, in order to power the home as well as any future electric vehicles the family might park in the garage. The home would be all electric, so solar panels could provide all the power. The project also aimed for passive survivability — that is, the home would remain habitable if the grid went down during a blizzard or heat wave. Just as the health of an ecosystem depends on the delicate balance

Graham retrofit Facts
Design/Build Ecofutures inc.

Architecture DaJ Design structural engineering Jon X. Giltner & assoc. Mechanical engineering PcD Engineering solar thermal service & solar Enterprises construction bioterra constructors PV Array Size 6.02 kilowatts Projected PV Production 8,300 kilowatt-hours/year Expected Household Consumption 7,600 k Wh/year Actual Household Consumption 7,400 k Wh/year Primary Heat Source solar thermal hot water Backup Heat Source 9-k W thermolec modulating electric boiler Primary Hot Water Source 180 evacuated tubes Solar Thermal Storage two 168-gallon stainless steel tanks

of interdependent elements, the success of a high-performance building relies on integration of all materials and systems from the beginning of the design process. We adopted a whole-house design approach, considering energy efficiency and renewable energy production measures, performance and commissioning monitoring needs, conservation of natural resources and high indoor air quality.

The design team included a project manager, an architect, structural and mechanical engineers, a solar thermal designer and an installation contractor with 30 years’ experience.

Appliance, envelope improvements Boost efficiency

We began the design process by analyzing the electrical demands of the home and then used energy modeling software to understand heat and energy flows. The goal was to produce a much tighter envelope to improve the home’s passive survivability.

At the most basic level, we replaced inefficient appliances and put electronics on a separate switch in order to eliminate phantom loads. The owners already had an Energy Star washer and dryer, as well as a clothesline, but a refrigerator and electric oven were added to eliminate the need for a natural gas supply. We routed potable solar-heated water directly to the kitchen faucet, bypassing the domestic water heating system and reducing energy needed in the process. Tall windows and skylights were incorporated into the new addition to provide deep-penetration daylighting, nearly eliminating the need for lights during the day. For electric lighting needs, energy-efficient CFLs were used throughout the home.

Changes to the building envelope help keep cool air in during the summer and warm air in during the winter, with minimal help from cooling and heating equipment. This required frame and insulation modifications. Plenty of insulation is a good thing, but a conven-