Air infiltration can be a significant component of thermal losses in residential buildings. In the Home Energy Saver, we calculate the energy impact of air infiltration in the DOE-2 simulation model, based on the leakage area of the thermal shell and location-specific weather data. Although leakage area can be measured using diagnostic testing such as with a blower door, few homeowners know the leakage area of their home, so we provide two options: 1) A simplified estimate based on building characteristics and 2) Direct entry of the measured leakage at 50 pascals (CFM50). 1. Estimate of Building Characteristics
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Core Model | ||||||
Coefficients: | ||||||
Estimate | Std. Error | t value | Pr(>|t|) | |||
Cfloor area | -2.08E-03 | 1.79E-05 | -116.003 | < 2e-16 | *** | |
CHeight | 6.38E-02 | 1.25E-03 | 50.912 | < 2e-16 | *** | |
Cvintage | Before 1960 | -2.50E-01 | 7.05E-03 | -35.418 | < 2e-16 | *** |
1960-69 | -4.33E-01 | 8.11E-03 | -53.381 | < 2e-16 | *** | |
1970-79 | -4.52E-01 | 7.62E-03 | -59.293 | < 2e-16 | *** | |
1980-89 | -6.54E-01 | 8.36E-03 | -78.192 | < 2e-16 | *** | |
1990-99 | -9.15E-01 | 8.16E-03 | -112.192 | < 2e-16 | *** | |
2000 and after | -1.06E+00 | 7.48E-03 | -141.405 | < 2e-16 | *** | |
CIECC | IECC Map | |||||
A - Humid | A-1,2 | 4.73E-01 | 1.02E-02 | 46.564 | < 2e-16 | *** |
A-3 | 2.53E-01 | 6.53E-03 | 38.724 | < 2e-16 | *** | |
A-4 | 3.26E-01 | 5.86E-03 | 55.618 | < 2e-16 | *** | |
A-5 | 1.12E-01 | 5.51E-03 | 20.284 | < 2e-16 | *** | |
A-6,7 | 0 | -- | -- | -- | -- | |
B - Dry | B-2,3 | -3.76E-02 | 7.59E-03 | -4.946 | 7.57E-07 | *** |
B-4,5 | -8.77E-03 | 6.84E-03 | -1.283 | 0.199644 | ||
B-6 | 1.94E-02 | 9.88E-03 | 1.968 | 0.049078 | * | |
C - Marine | C-3 | 4.83E-02 | 1.41E-02 | 3.431 | 0.000602 | *** |
C-4 | 2.58E-01 | 1.13E-02 | 22.803 | < 2e-16 | *** | |
Alaska | AK-7 | 2.56E-02 | 5.89E-03 | 4.341 | 1.42E-05 | *** |
AK-8 | -5.12E-01 | 9.38E-03 | -54.549 | < 2e-16 | *** | |
Coefficients | |||||
Cfoundation | Estimate | Std. Error | t value | Pr(>|t|) | |
Slab | -0.036992 | 0.007092 | -5.216 | 1.85E-07 | *** |
Conditioned basement / unvented crawlspace |
0.108713 | 0.004923 | 22.084 | < 2e-16 | *** |
Unconditioned basement / vented crawlspace |
0.180352 | 0.005768 | 31.269 | < 2e-16 | *** |
Coefficients: | |||||
Cduct | Estimate | Std. Error | t value | Pr(>|t|) | |
Conditioned space | -0.12381 | 0.02546 | -4.863 | 1.53E-06 | *** |
Uncond attic/basement | 0.07126 | 0.03387 | 2.104 | 3.59E-02 | * |
Vented crawlspace | 0.18072 | 0.03826 | 4.723 | 2.98E-06 | *** |
2. Direct Entry of Measured Leakage
Building shell leakage is typically measured using a blower door that pressurizes the living space to 50 pascals. This measurement is converted to fractional leakage area using the following equations:Q50si = Q50ip x 0.0004719474 ft3/min / m3/sec
Q4 = Q50si x (4 / 50) 0.65
ELA = Q4 / (((2 / 1.2) x 4)0.5)
FLA = (ELA / (0.09290304 m2 / ft2)) / A
Where:
Q50 - Air flow measured at 50 pascals (ft3/min for ip and m3/sec for si)
Q4 - Air flow at 4 pascals
ELA - Effective leakage area (in m2)
FLA - Fractional leakage area
A - Floor Area (ft2)