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Hughes Construction: Lexington, NC
Two summary reports are available for this field evaluation:
Heating energy use, adjusted to remove the effects of air infiltration and duct losses, was between 5.5 and 12.7 percent less than the wood baseline for all the alternative structural materials.
Cooling energy use, adjusted to remove the effects of air infiltration and duct losses, was less than the wood baseline for the ICF (16.6% less) and AAC units (6.5% less), while the composite panel building used slightly more (2.4%) cooling energy.
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Building #1 ICF |
Building #2 Composite Panel |
Building #3 Wood |
Building #4 AAC |
Labor time for structural wall (hours) |
131 |
68.7 |
33.9 |
186.4 |
Apparent Field Sound Transmission Class (Sound Attenuation) |
End wall: 46 |
End Wall: 39 |
End Wall: 42 |
End Wall: 45 |
Front Wall: 32 |
Front Wall: 30 |
Front Wall: 31 |
Front Wall: 32 |
Blower door test results (estimated ACHnat) |
North Unit:* 0.30 |
North Unit:* 0.37 |
North Unit: 0.31 |
North Unit: 0.40 |
South Unit: 0.37 |
South Unit: 0.33 |
South Unit: 0.28 |
South Unit: 0.44 |
Duct leakage (as % of conditioned space) |
North Unit: 2.2% |
North Unit: 2.7% |
North Unit: 2.4% |
North Unit: 3.1% |
South Unit: 3.1% |
South Unit: 3.5% |
South Unit: 2.6% |
South Unit: 4.0% |
Heating energy use (kWh during test period, south units)** |
Measured: 663 |
Measured: 633 |
Measured: 658 |
Measured: 736 |
Adjusted: 449 |
Adjusted: 486 |
Adjusted: 514 |
Adjusted: 464 |
Cooling energy use (kWh during test period, south units)** |
Measured: 216 |
Measured: 266 |
Measured: 256 |
Measured: 247 |
Adjusted: 206 |
Adjusted: 253 |
Adjusted: 247 |
Adjusted: 233 |
* Noted units have unvented crawl spaces
**Figures were adjusted to remove differences in air and duct leakage.
Comparison of Unvented Versus Vented Crawlspace
- Sensors indicated that moisture formed on the exterior walls of the vented and unvented crawlspaces. However, the unvented crawlspace sensors showed that moisture did not form on the joists, while the vented crawlspace showed water formation at joists.
- Absolute humidity level was lower and more stable in the unvented crawlspaces than in the vented crawlspaces.
Thermal Mass Effect on Total Energy Consumption and Time of Use
- There did not appear to be an effect on peak energy use of the higher thermal mass buildings, with peak energy use falling very close for all buildings. In fact, peak cooling energy use occurred earlier in the ICF building than the wood baseline.
- Peak energy for all of the alternative material units was lower than that for the wood units.
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Building #1 ICF
| Building #2 Composite Panel
| Building #3 Wood
| Building #4 AAC
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Total Cost
| $88,316 |
$78,769 |
$74,193 |
$83,801 |
Construction Cost
| $43.12 |
$38.46 |
$36.23 |
$40.92 |
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