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Energy Efficiency
This house was built to use less energy. The shell is air sealed and insulated by four inches of continuous polyisocyanurate rigid foam insulation under the basement slab and up from the footings to the peak of the house (attic is conditioned, useful space). There is very little thermal bridging, as the only major penetrations through this thermal barrier are the doors, windows and chimney.
This home is heated primarily by a WaterFurnace geothermal heat pump, the most energy efficient type of central heating system available today. During sunny winter days, the large south-facing windows warm the family room and kitchen wonderfully. Finally, the Jotul woodstove provides economical space heating in the evening.
Except the wood stove (about 1 cord of hardwood), this is an all electric
house. During the last twelve months we used a total of about 12,156 kWh.
Electric Use (based on 8/1/09 to 8/1/10)
| kWh | Cost | |
| Heating | 6,723 |
$1,109 |
plus $175 for a cord of hardwood |
| Hot Water | 1,146 |
189 |
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| Air Conditioning | 462 |
76 |
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| Lighting, TV, Etc. | 3,825 | 631 | |
| Totals: | 12,156 |
$2,006 |
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In 2004, we used 18,500 kWh for all our electric energy needs – heat, air
conditioning, hot water, cooking, TV & computers, lighting, etc. A series
of initiatives has reduced our usage by over 45% (-8,500 kWh) while
our growing children (were 2 & 5, now 9 & 12) are using quite a
bit more (+2,156). That is life! We can reduce our electric usage
further with
more efficient clothes, dish washer, TV and more LED lighting,
and with further training! Still, as we are today, Net Zero Energy
for this house
is possible at a reasonable cost, as the cost of solar electric
has decreased significantly over the last 5 years as well.
The three keys to this low electric usage are the energy efficient shell/envelop,
energy conservation habits of the household (among other things,
we keep our thermostat at 67 degrees all winter, and enjoy solar
heat during the
day and wood fires most evenings), and the highly efficient WaterFurnace
geothermal heat pump (installed in 2008). The heat pump moves heat
from the earth 3.5 times more efficiently than heat can be created
with electricity
by resistance heating. It cools even more efficiently (16.7 EER).
As a matter of fact, during the recent hot spell (7/9/10 to 7/16/10,
seven full days)
we ran the AC 24x7, using a total of 158 kWh, costing $26.07, --
for the whole week!
The most recent energy saving initiative we implemented was to install a used solar domestic hot water system. This system has an 80 gallon preheat tank and four flat plat solar collectors. Plus, with the preheat tank we can take advantage of excess heat from the heat pump desuperheater during the winter. The combination of using mostly solar energy collected during the spring, summer and fall and the efficient water heating by the desuperheater during primarily the winter heating season should reduce hot water costs by over 60% annually, which will be increasingly important as our children start taking more and longer showers.
Pictures – see next web page
Most Energy Efficient
The cost to deliver 1 million BTUs, based on NYSERDA’s Home Performance standard fuel rates and currently available high efficiency heating systems is listed below.
| Fuel |
Heating System |
AFUE |
Cost/mmBTUs |
| Electric | Ground-source Heat Pump | 350% | $15.86 |
| Wood | Wood Stove | 75% | $16.67 |
| Natural Gas | Furnace | 96% | $17.59 |
| Natural Gas | Boiler – water | 95% | $17.40 |
| Pellets | Pellet Stove | 80% | $20.70 |
| Fuel Oil | Furnace | 87% | $33.47 |
| Fuel Oil | Boiler – water | 86% | $33.86 |
| Fuel Oil | Boiler – steam | 81% | $35.95 |
| Propane | Furnace | 96% | $39.16 |
| Propane | Boiler-water | 95% | $39.57 |
| Electric | Resistance Heat | 100% | $47.17 |
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A series of initiatives
Over the last four years we reduced our electric usage by doing the following:
- Serendipity – our electric dryer broke. Mostly my wife decided we could do without this energy hog. I built a Linear Solar Dehydrator (LSD – aka, clothes line) and she bought clothes racks. We haven’t used a watt of electric since to dry clothes. Estimated annual savings about 1300 kWh.
- I made three passes through our house replacing electric sucking incandescent bulbs with CFLs (compact florescent lights) and in some cases LED (light emitting diode) bulbs. Estimated annual savings 600 kWh.
- We replaced our 1984 18 cubic foot refrigerator with a no frills, Energy Star 21 cubic foot refrigerator. We have two kids now, so the extra space was necessary and is much appreciated now. Estimated annual savings 800 kWh.
- I air sealed our basement and dramatically reduced the summer humidity level, eliminating the need for a dehumidifier. Estimated annual savings, about 600 kWh.
- Serendipity strikes again – our geothermal heat pump heat exchanger developed a crack. Replacing the heat exchanger would cost about half of what replacing the whole heat pump would cost and we’d still have a 20 year old heat pump. So we replaced the heat pump with an updated mechanical marvel with a COP (coefficient of performance) almost 30% higher than the original one. Estimated annual savings 2,400 kWh.
- Greater family awareness of energy resulted in shutting off lights and TV when not used, using less hot water, using less air conditioning, tolerating 64 degrees on the few coldest nights and not using supplemental electric heat, etc. Estimated annual savings 1,300 kWh.
- Installed a four-panel solar domestic hot water heating system with an 80 gallon solar tank that is also connected to geothermal heatpump desuperheater. Estimated annual savings is 1500 kWh.
Total Savings over 8,500 kWh or about $1,400 annually.
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Net Zero Energy
For about $24,500, which is net of currently available rebates and incentives, Alteris Renewables will install a 10.5 kW solar system, on a ground mounted array in the back yard. This system would deliver about 12,000 kWh annually. Then our house would be within a cord of wood of being Net Zero Energy. The only future utility cost would be the monthly connect charge!
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Home for Sale
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Energy Efficiency
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For questions or to
schedule a visit, call
Dan at (518) 339-0183
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