Imagine a home that captures from the SUN most or all the energy required for heating, cooling, water heating, lighting and appliances. While it is a challenge to design, build, and pay for such a home, it can help build a more efficient and renewable energy future. Hundreds of such homes exist in California Colorado
In truth, the typical Colorado Zero Energy Home (ZEH) consumes some fossil fuel on site and buys a portion of its electricity from the utility grid. But it captures extra solar electricity and feeds any excess back into the utility lines.
I live in a Zero Energy Home, and this is my checklist to help you move towards the ZEH concept.
In truth, the typical Colorado Zero Energy Home (ZEH) consumes some fossil fuel on site and buys a portion of its electricity from the utility grid. But it captures extra solar electricity and feeds any excess back into the utility lines.
I live in a Zero Energy Home, and this is my checklist to help you move towards the ZEH concept.
Focus on efficiency throughout the design-build process. Think efficiency first, efficiency second, solar third.
Start with a home 50 percent more efficient than building code requires. That means high levels of wall, ceiling and foundation insulation; R-25, R-50 and R-20, respectively. Use sprayed, blown or foam insulation products to increase energy performance.
Then you need exceptionally tight construction, verified by a blower-door test. Specify “tighter than 0.20 natural air-changes per hour” for your builder, and be sure to add mechanical ventilation.
Add efficient windows to balance interior daylight, provide connection to the outdoors, and capture the sun’s seasonal heating benefit.
To enhance passive solar performance, your design needs to incorporate some heavy-weight materials—typically masonry walls or floors that soak up excess solar energy captured during the day to help your home stay warm overnight. As you add more south-facing windows, figure you’ll need an exposed slab floor along your south side or several interior brick or block walls (blocks filled solid with cement).
Start with a home 50 percent more efficient than building code requires. That means high levels of wall, ceiling and foundation insulation; R-25, R-50 and R-20, respectively. Use sprayed, blown or foam insulation products to increase energy performance.
Then you need exceptionally tight construction, verified by a blower-door test. Specify “tighter than 0.20 natural air-changes per hour” for your builder, and be sure to add mechanical ventilation.
Add efficient windows to balance interior daylight, provide connection to the outdoors, and capture the sun’s seasonal heating benefit.
To enhance passive solar performance, your design needs to incorporate some heavy-weight materials—typically masonry walls or floors that soak up excess solar energy captured during the day to help your home stay warm overnight. As you add more south-facing windows, figure you’ll need an exposed slab floor along your south side or several interior brick or block walls (blocks filled solid with cement).
Typically, this isn’t as easy as it sounds. For optimum passive solar design—capturing useful winter sun while minimizing unwanted summertime solar—the long axis of your home should run within 15 degrees of an east-west orientation.
Locating such a lot within a planned subdivision can be tough, but keeping looking until you find one. In rural applications, this is a slam dunk; you only need to guard against hills or existing trees that will shade your building site.
Along theFront Range and Western Slope, including two-foot overhangs that are a solid foot above your south-wall windows will keep out unwanted summertime solar gains. As you move higher into the mountains where heating loads last into June and start in late August, those overhangs can be reduced or eliminated.
Locating such a lot within a planned subdivision can be tough, but keeping looking until you find one. In rural applications, this is a slam dunk; you only need to guard against hills or existing trees that will shade your building site.
Along the
The last efficiency piece often gets overlooked yet is easy to implement: shop for the most efficient appliances available (aceee.org).
You can buy a 21 cubic-foot refrigerator that draws just 420 kilowatt-hours of electricity per year; surprisingly, they cost about the same as models on showroom floors that use 25 to 50 percent more energy. Shop only for front-loading washing machines. Since electric cook-tops and ovens use too much electricity to be cost-effectively solar powered, pick a gas range/oven unit (propane where natural gas isn’t available). If you must have a clothes dryer (hey, your author has lived 28 years and raised two kids using just a solar dryer), consider one of the combo European designs that is vent-less; it washes clothes, then dries them by dehumidification.
Buy and install compact fluorescent lights. For his ZEH research home, Jammie Sabin, president of Aspen Homes of Colorado Inc., selected light fixtures that use nothing but pin-type bulbs instead of the screw-in models. He swears by the improved light quality.
It is possible to dramatically downsize your heating system. When using a furnace, specify a unit using an ECM motor; they draw just 25 percent of the power used by a standard blower. Select a whole-house fan to cool off your well-oriented house, while shutting your windows during the day.
You can buy a 21 cubic-foot refrigerator that draws just 420 kilowatt-hours of electricity per year; surprisingly, they cost about the same as models on showroom floors that use 25 to 50 percent more energy. Shop only for front-loading washing machines. Since electric cook-tops and ovens use too much electricity to be cost-effectively solar powered, pick a gas range/oven unit (propane where natural gas isn’t available). If you must have a clothes dryer (hey, your author has lived 28 years and raised two kids using just a solar dryer), consider one of the combo European designs that is vent-less; it washes clothes, then dries them by dehumidification.
Buy and install compact fluorescent lights. For his ZEH research home, Jammie Sabin, president of Aspen Homes of Colorado Inc., selected light fixtures that use nothing but pin-type bulbs instead of the screw-in models. He swears by the improved light quality.
It is possible to dramatically downsize your heating system. When using a furnace, specify a unit using an ECM motor; they draw just 25 percent of the power used by a standard blower. Select a whole-house fan to cool off your well-oriented house, while shutting your windows during the day.
Figure you’ll need a two-panel collection system mounted on your south-facing roof. It works best with the panels tilted up at 40 degrees from horizontal. With pump, controls and a storage tank, the installed cost will run upwards of $4,000 (less if you use recycled solar collectors, more if you select a system powered by a solar-electric pump).
As a general rule, ask for an over-sized water storage tank compared to the collectors—perhaps two gallons of storage per square foot of roof-mounted solar collector.
As a general rule, ask for an over-sized water storage tank compared to the collectors—perhaps two gallons of storage per square foot of roof-mounted solar collector.
In a 2,000 square-foot home built as described above, with electric loads squeezed way down, you should be able to generate all your electricity with a 2.0 kilowatt solar electric (photovoltaic, or PV) system. Since demand is high for these systems, expect to pay upwards of $15,000 installed, for a system tied to the utility grid.
In windy rural and mountain sites, consider a hybrid system. Coupling a 500-watt wind generator with a 1.5 kilowatt PV system allows you to generate more electricity during stormy winter weather. The hybrid approach could lower your costs by $1,000 to $2,000, compared to a similarly sized all-PV system.
Check with your local utility to see if they will net-meter your home, and pay for the excess electricity. If it’s not yet available expect to pay another $7,000 to $9,000 for an off-grid battery storage and back-up generator.
Living in a home designed with the sun in mind will be one you are proud to pass on to the next generation of homeowners. With some planning and enough resources, you can be part of the next home building frontier.
In windy rural and mountain sites, consider a hybrid system. Coupling a 500-watt wind generator with a 1.5 kilowatt PV system allows you to generate more electricity during stormy winter weather. The hybrid approach could lower your costs by $1,000 to $2,000, compared to a similarly sized all-PV system.
Check with your local utility to see if they will net-meter your home, and pay for the excess electricity. If it’s not yet available expect to pay another $7,000 to $9,000 for an off-grid battery storage and back-up generator.
Living in a home designed with the sun in mind will be one you are proud to pass on to the next generation of homeowners. With some planning and enough resources, you can be part of the next home building frontier.
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