Zero Energy Homes for Region VII

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Zero Energy Homes for Region VII

• Jeff Christian
• Oak Ridge National Laboratory
• Going Green in ASHRAE Region VII
• August 23, 2007

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Focus on Zero Energy House 5

• ZEH5 analysis
• Zero energy peak potential
• Commercial house plans

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First four houses to sell solar power to the
largest public electric utility in U.S.

•  

• Solar credits 1.00/day
• Net off site total energy cost 1.00 to 0.41/day
  
• Construction cost 100,000- 221,000

ZEH1 built in 2002
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ZEH2 August 2004 total monthly energy bill 16.70
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ZEH 3 entire heating season cost 6
ZEH5 an unoccupied test house for two year period

• ZEH5 has 12 months of performance data
  conditioning 1232 ft2
• Testing two ton unit conditioning 2600 ft2 in
  2007
• Geothermal horizontal water loop in existing
  excavations
• R-21 walls, R-36 roof
• Exterior insulated 2 hollow core CMU
• Linked foundation construction system to
  geothermal

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ZEH4 measured 0.42/day in 2006 for all off-site
energy, update
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ZEH4 modeling validation
0.50/day for 1200 ft2
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6-pipe Heat exchanger installed in ZEH5 overcut
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3 pipes pinned to the clay soil wall and 3 spread
about a foot apart at base of the overcut
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Geothermal loop utilized water trench dug out
another 4 foot deeper
Water trench
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Heat exchangers also run in trenching for sewer
tap
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Ground Pipe Installation and Sensors (ZEH5)
5 ft
33 ft
TC7
TC 1,2,3,4,5,6,8,9 Thermal couple for
Temperature on the middle pipe TC7 Far field
ground temperature ? Ground pipe header
30 ft
Water Meter
20 ft
33 ft
TC3
TC4
13 ft
TC9
TC8
30 ft
Supply Return Pipes
22 ft
TC6
TC2
TC5
13 ft
TC1
2.53 ft
30 ft
Sewer Tap
50 ft
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Measured temperatures, Jan. 2006- July 23, 2007
Temperature oF
EWT/LWT
July 23 2006
July 23 2007
Farfield
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Measured temperatures, Jan. 2006- August 21,
2007, 100 am
Last Summer
This Summer
Farfield
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Air side problems?
7 lower while heating
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Thus far in 2007 ZEH5 two-story using 55 more
total energy for cooling
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But, on a per unit area of conditioned space 28
less cooling energy is needed by the GSHP

• In May-July ZEH4 a 2 story, 1200 ft2 with SEER
  17 air source heat pump used 0.74 kWh/ft2
• Over the same period, exposed to the same weather
  and with same orientation, ZEH5 - 2600 ft2 with
  GSHP (ground coil in existing excavations) used
  0.53 kWh/ft2

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Performance involves coupled heat and moisture
transfer processes
Solar radiation,rain, wind
Freezing, thawing
Convection
Conduction,moisture flow
Conduction,moisture flow
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Generating a data base for design model
development and validation

• Model validation using ZEH5 data
• Heavy clay soil
• 6 - 3/4 inch HDPE 500 ft loops in 250 ft trench
• Walkout basement with R-10 fiberglass insulation
  drainage board
• At least two years of 15 minute data
• Last summer peak EWT 97 F, last week 102 F

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Zero Peak Energy
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ZEH reduces summer peak loads by 40 with no
Demand side Management
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With DSM these houses can reach zero peak ZEH5
Hourly energy on TVA peak day, August 8, 2007
Wh
TVA record peak, of 33,344 MW
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Thermal Comfort Maintained
Temperature F and RH
Temperature
RH
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ZEH5 Hourly power demand on TVA all time peak
days in August 2007
Wh
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ZEH7 SIP walls and roof, less than /day, HERS
index 37, 37 Solar, enough roof area to be
ZEH ready
2640 ft2
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Upscale version with same energy performance

• 8/12 pitch roof
• Cedar shakes
• Crab Orchard Stone
• Stair Punch out
• Cost estimate 375K

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Thank you!

• Jeff Christian
• ChristianJE_at_ORNL.gov