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
Primary Hot Water Source 180 evacuated tubes
Solar Thermal Storage two 168-gallon stainless
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-
Tall windows bring daylight deep into the house. All interior finishes
are low- or zero-VOC.