Monday, December 8, 2008

Energy Consumption for LEED

Active techniques to reduce consumption of energy include:

1. Two two-stage zoned ground-source heat pumps provide heating and cooling. The heat pumps provide air distribution that will adjust to the variation in loads throughout the areas of the house throughout the day and will provide both temperature and dehumidification control.

2. A desuperheater is coupled to each of the two geothermal heat pumps and heats water with energy that would otherwise be given up to the heat sink of the closed loop wells. When the heat pumps are operating, hot water is virtually free. Hot water is stored in high efficiency hot water heaters that serve as backup hot water generators when the geothermal heat pump system is not in operation.

2. An energy recovery ventilator provides balanced introduction of fresh filter/conditioned air and reclamation of invested energy from air typically exhausted from bathrooms, kitchen and laundry.

3. Lower capacity high efficiency two-stage zoned geothermal heat pumps will provide the necessary heating and cooling with controlled airflow to the zones that require conditioned air which can be as low as a few hundred cfm per zone. For most of the year 1200 cfm provides required conditioning, 2000 cfm on the very hottest or coldest days compared to 3,600 cfm required in code compliant designs.

4. A net-metered roof mounted 3.1 kilowatt photovoltaic system. The system, consisting of 18 high-efficiency monocrystalline photovoltaic modules, is mounted on the south-facing portion of the butterfly roof. Through the Georgia Power Net Metering System, all power generated from the photovoltaic system is independently metered and made available to Georgia Power for it’s Green Energy program. Georgia Power pays 17.4 cents per kilowatt hour for power generated by the system. Energy consumed by the house is obtained from the grid at 8.64 cents per kilowatt hour and is monitored by a separate meter. As incentive, this system has received a $10,500 state tax credit and is eligible for a $2,000 federal tax credit.
The system was installed and activated shortly after completion of framing and roofing. It generated and sold power during the remainder of the construction period.

5. Energy Star appliances.

6. All light fixtures employ LEDs or are fluorescent Energy Star rated and, in total, consume 1/10 of the power of a similar code compliant house using conventional fixtures.

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