2021
Up and Running with the Passive House Planning Package (9.7 IP) Module 1 | Class 3 | Surface Exposure
Q: How do you calculate annual the heat loss of a surface? A: QT-srfc = Areasrfc (
In 1. 2. 3. 4.
ft2
)
U-Valuesrfc ( Btu /
hr-ft2-F
)
ft (%)
Gt ( kFhr / yr)
order to calculate the transmission heat loss for each surface of a building, we need to: Determine the surface area Determine the surface’s U-Value Determine the temperature correction factor Determine the annual difference in temperature between inside and outside
bldgtyp | NYPH
NYPH: Up and Running with PHPP
1
2021
Q: How do you calculate annual the heat loss of a surface? A: QT-srfc = Areasrfc ( ft2 )
In 1. 2. 3. 4.
U-Valuesrfc ( Btu / hr-ft2-F )
ft (%)
Gt ( kFhr / yr)
order to calculate the transmission heat loss for each surface of a building, we need to: Determine the surface area Determine the surface’s U-Value Determine the temperature correction factor Determine the annual difference in temperature between inside and outside
bldgtyp | NYPH
Surface Exposure
NYPH: Up and Running with PHPP
2
2021
Gt ? • https://www.ladybug.tools/epwmap/ • https://energyplus.net/weather
bldgtyp | NYPH
bldgtyp | NYPH
NYPH: Up and Running with PHPP
3
2021
bldgtyp | NYPH
bldgtyp | NYPH
NYPH: Up and Running with PHPP
4
2021
But! not every surface on our building is exposed to the outdoor air. Some will be exposed to zones which are warmer than the outdoor air.
68F ?
7.9F
?
bldgtyp | NYPH
Example: 4” XPS Insulation (R-20) QT-surface = Areasurface
68 F
U-Valuesurface
ft
Gt
10’-0”
Areasurface = 10’ x 30’ = 300ft2 28 F
U-Valuesurface = 1/20 = 0.05 Btu/hr-ft2-F ft = 1.0
30’-0”
Gt = 120 kFh/yr
QT-surface = 300ft2
0.05 Btu/hr-ft2-F
1
120 kFhr/y
QT-surface = 1,800 Btu bldgtyp | NYPH
NYPH: Up and Running with PHPP
5
2021
Example: 4” XPS Insulation (R-20) @ 0.38 ft QT-surface = Areasurface
68 F
U-Valuesurface
ft
Gt
10’-0”
Areasurface = 10’ x 30’ = 300ft2 28 F
U-Valuesurface = 1/20 = 0.05 Btu/hr-ft2-F ft = 0.38
30’-0”
Gt = 120 kFh/yr
QT-surface = 300ft2
0.05 Btu/hr-ft2-F
0.38
120 kFhr/y
QT-surface = 684 Btu bldgtyp | NYPH
bldgtyp | NYPH
NYPH: Up and Running with PHPP
6
2021
bldgtyp | NYPH
NYPH: Up and Running with PHPP
7