Highlights of the 2005 Denver Tour of Solar Homes

Avenson Home 

The Colorado 2005 Tour of Solar Homes in Denver highlighted the Avenson home, which had a cutting edge passive solar design at the time it was built in 1982.  The home contains 2,000 square feet (sf) of floor area, and the Nedlaw Construction Company in Walden built it at a cost of about $45 / sf. 

The home received a 5-star rating from a home energy rater, which makes it an E-Star certified home.  The utility bills are about $115 a year for natural gas to heat the house and supply domestic hot water.  Other features include:

• South facing glass

• Removable, transparent, exterior summer shades

• Interior mass of brick and rock box storage

• Air stratification fans

• Tinted, double-pane windows with removable storm windows

• 2’ x 4’ exterior walls with 2 inches of extruded polystyrene insulation

• Insulated foundation

• Weather stripping on attic access panel

• Caulked and sealed electrical outlet boxes

• Evaporative cooler

• Airlock entry

• Weather station on the roof connected to the computer that runs the Mylar window shades

• Compact fluorescent lamps

• LED nightlights with light sensors

• Fiber optic bedroom closet light

• Motion sensor controlling the light switches lights

• Timers controlling bathroom fans

• Insulated hot water tank

• Energy Star appliances.

If the Avensons had it to do over again, there are several things that they would do differently:

• Expand the house east and west to have more floor space

• Extend the clerestory windows across the whole length of the house for more heat and light

• Increase the thickness of exterior walls to add more insulation

• Increase air flow into the rock storage to help with stratification of hot air toward the ceilings

• Increase the amount of the rock storage by four times to help reduce the temperature swings on sunny days and further decrease the need for using natural gas during spells of cold and cloudy weather. 

Burrows Home

The Burrows home was a state-of-the-art solar home when it was built in 1991.  Pamm McFadden of the  Elements Design Group in Boulder and Richard Burrows designed it to contains 2,000 square feet (sf) of floor area with 200 sf of sunroom.  Boa Construction and Richard Burrows demolished an old house and built the new home on the same site using many of the materials from the old house. 

The home is “all electric,” which means all of the appliances and auxiliary heating and cooling equipment runs on electricity.  Monthly bills for electricity run about $40 to $60.  Other features include:

• Passive solar design

• Sunspace with a small pond to add humidity

• Thermal mass consisting of stone walls in the sunspace with recirculation of warm air to the north bedrooms

• Insulated slab-on-grade, finished with tile and stain

• West wall is bermed into 8 feet of concrete

• North walls are 8” thick, east and south walls are 6” to accommodate insulation to R-30

• Cement tile roof is insulated to R-60

• Low-e Hurd windows

• Domestic hot water supplied by solar thermal panels and Enviro-Vent heat pump

• Wood stove with heat re-circulation

Healey Home

The Healy Home has 4,300 square feet (sf) of floor area. Pat Healey designed and built the home in 1998 at a cost of $79 / sf.   It is built entirely with ICF blocks filled with concrete.  One interesting feature of this home is that Healey designed and plumbed it to install PV panels at a later date.  By pre-installing the wiring and connections, he will be able to install PV less expensively.

The electric bills run about $55 to $75 per month, which also includes costs for operating an outdoor hot-tub.  Propane consumption runs about 2.3 gallons in the summer and 4 gallons in the winter.  Other features include:

• Sun-tempered spaces facing south.

• Skylights for natural lighting

• Radiant heat from a propane boiler.

• R–30 blown-in cellulose insulation under the roof

• Low-e vinyl windows made by Millgard

• Outside deck made of Choice recycled plastic

• Whole-house fan for cooling, which is used occasionally

• Heated sidewalk and driveway pad

Jones Home

The Jones home was a state-of-the-art passive solar home when it was built in 1982.  The home contains 3,330 square feet of floor area, and utility bills average $100 per month.  Some features include:

• Solar assisted thermal heating.

• Thermal mass in flooring (dark ceramic tiles) and walls.

• PV-tied to the electric grid.

• Energy Star rated washer and dryer.

• Xeriscaping.

Zero Energy Habitat For Humanity Home

The newly built zero-energy Habitat for Humanity Home is Energy Star rated at five stars and is expected to produce as much energy as it consumes in a typical year.  The home contains 1,300 square feet of floor area, and utility bills are expected to be about $30 a month.  Half of the utility bill, $15, is the monthly meter charge.  Other features include: 

• Solar hot water system with a drain-back 96 square foot solar collector and 200-gallon storage tank.   High efficiency Rinnai on-demand water heater as back-up for the solar system. 

• PV system rated at 4 kilowatts and interconnected with the utility grid. 

• Energy recovery system for mechanically introducing outside air.

• R-40 fiberglass insulated walls, R-60 blown fiberglass roof, R-30 under floor

• Double wall construction with one layer of vapor barrier per wall.

• Windows are double-paned with low-e coatings and with vinyl construction; west windows are triple-paned with a Mylar coating; south windows have a solar heat gain coefficient of 0.58.

• Energy Star refrigerator, which was donated by Maytag.

• Compact fluorescent lamps.

• Low flow toilets.

Construction waste reduction: recycled all cardboard; Used on-site river rock for landscaping; 2’ x 4’ lumber waste was turned into mulch. 

Habitat for Humanity of Metro Denver built the home in 2005 with support from the National Renewable Energy Laboratory in Golden, the U.S. Department of Energy, the U.S. Department of Housing and Urban Development, Energy Outreach Colorado, and the City of Arvada.  Altair Energy in Golden donated the PV system, and  Industrial Solar Technologies donated the solar hot water system.  Habitat for Humanity of Denver has won the Energy Star Efficient and Affordable Housing award for the last four years.

For more information, see NREL’s September 15 press release: http://www.nrel.gov/news/press/2005/3105_habitat_house.html