Net-Zero Surplus | Mitchell, OR

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Mitchell, OR exterior This exemplary case study demonstrates the economic possibilities for building and business owners alike. New construction projects offer a higher cost benefit when energy production offsets transportation costs as well as building costs.

The owners were able to produce enough energy to not only power the property, but were also able to produce excess to run an electric vehicle for more than 18,000 miles over a year. The Painted Hills project was designed and built by Zero Energy Plans as employee living quarters for the Oregon Park and Recreation Services.

Notable Economic Attributes

Mitchell, OR interior and solar panels The property is occupied 100% of the time, and poses significant economic attributes. The region has inclement weather patterns and gets significantly less sun than regions like California, Texas and Arizona. The building is equipped with a charging station to operate the park service electric vehicle and is producing excess power generation. The house‘s south-facing design optimized passive solar gains in winter, minimal gains during hot summer months.

They “Dialed it in”

According to designer and consultant Ted Clifton, “This house was about dialing it all in. If there was a way to crank the energy-use lower, without significantly raising the price, we did it. Since the completion of this house, we have continued to dial in the numbers.”

Upgrade Measures Included:

  • Use of slab floor and careful placement of windows to gather and store passive solar heat.
  • Air-tight building envelope, using SIPS panels from Big Sky R-Control, achieved 1.2 ACH @ -50 Pascal‘s.
  • Air-handling system designed to double as low-energy air conditioning system for swing seasons. Fan-Tech (mfg.) system also provides HEPA filtration and HRV.
  • HERS rating -15, but house is operating at -61, based on the first eight month of data. (Out of a possible 100% -15 represents, the building was rated at more than 100% or a minus of 15 points, but actual building operation is at minus 61, above 100% efficiency level.
  • Triple-glazed low-e windows from Atrium, U-values around .20, SHGC around .25 (varies by individual window size and configuration)
  • Insulated fiberglass doors from Code, U-value .16
  • Super-insulated finished concrete slab floor, with R-20 full coverage, and an additional R-10 foam insulation at the perimeter for 2‘ depth.
  • Careful attention was paid to flashing details and drainage at windows, doors, and at foundation insulation.
  • Ductless mini-split heat pump from Daikin, HSPF 10.1
  • Solar hot water heater, drain-back system, Bradford White high-efficiency 80-gal storage tank.
  • Energy-Star appliances, we searched out the lowest energy-use equipment for each appliance, including equipment from Whirlpool and Bosch.
  • 24-panel PV system (5.6 KWh) has provided 7,140 KWh in its first eight months of operation, more than enough to power the house and a small electric Park Service vehicle. 5,373 KWh have been returned to the grid, enough to power a Nissan Leaf more than 15,000 miles.
  • Enough room is left on the prime south-facing roof for an additional 10 PV panels, which would take the HERS rating down to about -40. This would allow the Painted Hills house to operate in the neighborhood of -80 HERS, and power an electric car, such as the Nissan Leaf, over 24,000 miles per year!

Energy Efficiency Case Study Data

PROPERTY CITY, STATE Mitchell, OR
SQUARE FOOTAGE 1002
NEW/EXISTING NEW
COST OF CONSTRUCTION $ 150,000
COST OF LAND N/A Property located on government, forestry land
EXISTING PROPERTY VALUE $ 150,000
COST OF RENEWABLES $ 40,000 Renewable systems and green upgrades
TAX CREDITS, REBATES $ 9,000
Utility (Elec) kWh rate $ 0.08 5.6 kW System, Ductless Heat Pump & Solar Hot Water
Monthly electricity savings $ 144
Yearly electricity savings $ 1,728
Yearly gas & water savings $ 912
Yearly utility savings $ 2,640
Monthly EV* Gas Reduction $ 244
Yearly EV* Gas Reduction $ 2,926 **
2010-2011 Usage (kWh) Generation (kWh) Net (kWh) Potential Net Surplus Power & EV Savings
February 229 470 -241 $ 134
March 462 735 -273 $ 168
April 356 1,000 -644 $ 339
May 146 796 -650 $ 325
June 140 925 -785 $ 389
July 174 1,095 -921 $ 458
August 190 1,061 -871 $ 435
September 166 808 -642 $ 322
October 203 636 -433 $ 225
November 195 357 -162 $ 94
December 303 357 -54 $ 50
January 289 390 -101 $ 72
TOTAL 2,853 8,630 -5,777 $ 3,010
Total Upgrade Investment $ 31,000 Cost of renewables less tax credits
Formula 1, PV $ 32,900
Formula 2, SQ Ft * $25 $ 66,000 Power + Production, HERS -10
INCREMENTAL PROP VALUE $ 49,450 IPV not calculated with EV Savings, no allowance
NEW PROPERTY VALUE $ 199,450 $ 150,000 (existing property value) + $ 49,450 (IPV)
Traditional Payback $ 49,101 $ 31,000 (loan) + $ 18,101 (interest paid over 20.0 years)
**GEM Payback Method $ 39,680 $ 31,000 (loan) + $ 8,680 (interest paid over 10.3 years)
FUTURE VALUE (FV) $ 87,294 @ 5%, 20 years

Increases in utility prices of up to 30% within the next 5 years are not included in the calculations
* EV = Electric Vehicle quantified @ 18,286 average miles, Cost of EV not included in cost outlayAverage cost @ $ 4 per gallon gas, @ 25 mpg = $244 month
Est Savings = 2925.76
**GEM Payback Method includes extra energy savings pmt + Bi-Weekly payment
Utility prices expected increases of 30% in next 5 years not used in calculation