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Although renewable energy technologies have traditionally offered much better economies of sale for the commercial building and utility market, some technologies are developing to the point where they’ve become viable for housing units. While others still have a way to go, some recent technological advances suggest that the future may be here before we know it.

Cogeneration Heat and Power
With a combined heat- and power-generating efficiency of around 90%, as compared to between 30% and 40% for remotely located utility-generated electricity, this technology repurposes waste heat. According to the NAHB’s, just one 6-kW unit can create 10 gpm of hot water at 140°F to 150°F. Waste heat from electricity generation may be sufficient to heat an entire home, including water for domestic use.

NAHB does point out that initial cost for a CHP unit is generally twice the cost of conventional heating equipment, and payback rates will vary based on the cost of fuel and electricity, demand for waste heat, and the availability of net metering.

As such, the most viable applications are in cold climates with high electrical rates and low natural gas rates.

Solar Power
Although photovoltaics are currently the most common system used to power net-zero buildings, architect Katherine Austin recommends investing in solar hot water before PV for a faster payback. The West Coast architect urges more attention to multifamily settings, where larger arrays can be attached to expanded roof areas or parking lots—as the most cost-effective installments.

While PV efficiency continues to improve, however, progress still needs to be made with battery systems. They’re the weak link in creating site-based power that is both reliable and appealing to homeowners.

Roof-integrated Wind Turbines
Although building-integrated wind turbines are theoretically a great way to harness natural wind-generated power and eliminate traditional transmission losses, the technology has yet to find a technological and market balance viable for small buildings. Large, commercial properties are another story, however, where promising building mounted turbines are beginning to show up. For example, the three 225-kW wind turbines mounted on the Bahrain World Trade Center generate between 11% and 15% of the building’s energy needs.

Creating Electricity with Sewage
Researchers at Oregon State University have demonstrated that by coating a fuel cell with nanoparticles, they can generate enough current from sewage to power a light bulb or a small fan. Larger scale uses are probably a few years away.


Innovative Incentives
Austin notes that there is a major lack of incentive for homeowners to invest in even the most basic home improvements. Recognizing this, California’s Sonoma County has a program where homeowners can take out a loan for such energy upgrades, with payments coming off the property tax bill. In addition, “the loan goes with the house, if sold, and is not a personal burden of the homeowner,” she explains.

Included in Sonoma’s list of loan-eligible improvements are:

> Increasing insulation, particularly in the attic to R30 or R40, if possible.
> Installing photovoltaic systems, along with solar hot water.
> Replacing old heaters with 98% efficient HVAC units.
> Replacing heating and cooling with geothermal units or heat pumps.
> Installing a cool roof.
> Installing tankless water heaters.
> Replacing old windows with new energy-efficient units.
> Installing dual-flush or high-efficiency toilets.
> Replacing old light bulbs with compact fluorescents or LEDs.

Furthermore, in the town of Sebastopol, any remodel of more than 50% of the existing home or addition must be brought up to current energy codes, and the local utility, PG&E, offers rebates for replacing older refrigerators, dishwashers, washers, and dryers with new, energy-efficient appliances.

But like many greener products, energy-saving clients may mean little without changes if consumers don’t understand them. Baker stresses that appliances, water heaters, and heating and cooling systems should be run in energy-saving mode. “Unplug any non-essential devices when not in use, and buy and maintain the most efficient appliances.”


Did you know that a cordless drill charger typically drains about 5 watts, even when it’s not recharging a tool? It’s just one of hundreds of “vampire” power devices that add to household energy waste.

A few products are hitting the market that address phantom power (and it’s about time). For example, the AT&T ZERO Charger automatically stops charging once the cell phone is taken off the stand.

Also, Belkin offers a “smart” power strip that does a nice job. Up to five entertainment system components can be plugged into the strip, and are automatically shut down when the main device is clicked off. At the same time, two additional outlets are available for devices that require continuous power. The product also serves as a surge protector.

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