The 2030 Challenge & Current Energy Efficient Housing
James Petersen, P.E.Petersen Engineering
2007 Maine Affordable Housing ConferenceOctober 30th, 2007 Portland, ME
Petersen Engineering 2007
1
Construction Assumptions
Component Base Case
Glass 2-glaze low-e
Door -
Walls metal stud/batt fill
Garage Ceiling 6" batt
Roof 4" rigid polyisocyanurate
Infiltration .6 air changes/hour, 12 ACH50pa
Heat Loss 25 Btuh/sf
Petersen Engineering 2007
2
Portland Maine Project Petersen Engineering - 2007
Base Case - conventional construction
Input values are shown in yellow Calculated values are shown in blue
Outdoor Design Temp 0ΔT 70
Indoor Design Temp 70
Ground Temperature 50 Floor to Ground ΔT 20
Area[SF]R-Value
[hr-SF-[°F/Btu]U-Value
[Btu/hr-[SF-°F]UA- Value [Btu/hr-°F]
Heat Loss[Btu/hr]
Gross Wall 12,700.0
Window 3,300.0 2.5 0.400 1,320.0 92,400
Door 0.0 2.5 0.400 0.0 0
Net Wall 9,400.0 4.0 0.250 2,350.0 164,500
Garage Clg 6,000.0 10.0 0.100 600.0 42,000
Roof 6,000.0 25.0 0.040 240.0 16,800
Total Conditioned Floor Area 19,625.0
Ventilation Rate [CFM]
UA- Equiv. [Btu/hr-°F]
Heat Loss [Btu/hr]
Ventilation 900 293.0 20,507
Flr-toFlr Height
[FT]Building Volume
[CF]Infiltration Rate
[ACH]UA- Equiv. [Btu/hr-
°F]Heat Loss
[Btu/hr]
Infiltration 10.5 200,000 0.6 2,170.0 151,900
Building UA-Value 6,973 [Btu/hr-°F]
Building Peak Heat Load 488,107 [Btu/hr]
Load per Ft2 25 [Btu/hr/ft2]3
Petersen Engineering 2007
4
Petersen Engineering 2007
Construction Assumptions
Component Base Case Case 1
Glass 2-glaze low-e better 2-glaze low-e
Door - -
Walls metal stud/batt fill 3" cont. rigid polyiso.
Garage Ceiling 6" batt 3" cont. rigid polyiso.
Roof 4" rigid polyisocyanurate 8" cont. rigid polysio.
Infiltration .6 ACH, 12ACH50pa .2 ACH, 4ACH50pa
Heat Loss 25 Btuh/sf 11 Btuh/sf
5
Portland Maine Project Petersen Engineering 2007
Proposed Case 1 - Increased R-values/Decreased Infiltration
Input values are shown in yellow Calculated values are shown in blue
Outdoor Design Temp 0ΔT 70
Indoor Design Temp 70
Ground Temperature 50 Floor to Ground ΔT 20
Area [SF]
R-Value [hr-SF-[°F/Btu]
U-Value [Btu/hr-[SF-°F]
UA- Value [Btu/hr-°F]
Heat Loss[Btu/hr]
Gross Wall 12,700.0
Window 3,300.0 3.0 0.333 1,100.0 77,000.0
Door 0.0 3.0 0.333 0.0 0.0
Net Wall 9,400.0 18.0 0.056 522.2 36,555.6
Garage Clg 6,000.0 19.0 0.053 315.8 22,105.3
Roof 6,000.0 50.0 0.020 120.0 8,400.0
Total Conditioned Floor Area 19,625.0
Ventilation Rate [CFM]
UA- Equiv. [Btu/hr-°F]
Heat Loss [Btu/hr]
Ventilation 900 293.0 20,507
Flr-toFlr Height
[FT]Building Volume
[CF]Infiltration Rate
[ACH]UA- Equiv.
[Btu/hr-°F]Heat Loss
[Btu/hr]
Infiltration 10.5 200,000.00 0.2 723.3 50,633
Building UA-Value 3,074 [Btu/hr-°F]
Building Peak Heat Load 215,201 [Btu/hr]
Load per Ft2 11 [Btu/hr/ft2]6
Petersen Engineering 2007
7
Construction Assumptions
Component Base Case Case 1 Case 2
Glass 2-glaze low-ebetter 2-glaze low-e
3-glaze fiberglass frame/reduce area
Door - - -
Walls metal stud/batt fill3" cont. rigid polyiso.
3" rigid + cavity fill cellulose
Garage Ceiling 6" batt3" cont. rigid polyiso. 3" rigid + 6" batt
Roof4" rigid polyisocyanurate
8" cont. rigid polysio.
8" cont. rigid polysio.
Infiltration.6 ACH, 12 ACH50pa
.2 ACH, 4 ACH50pa
.1 ACH, 2 ACH50pa
Heat Loss 25 Btuh/sf 11 Btuh/sf 6 Btuh/sf
Petersen Engineering 2007
8
Portland Maine Project Petersen Engineering 2007
Proposed Case 2 - Increased R-values/Very Low Infiltration/Best Windows/Reduced Window Area
Input values are shown in yellow Calculated values are shown in blue
Outdoor Design Temp 0ΔT 70
Indoor Design Temp 70
Ground Temperature 50 Floor to Ground ΔT 20
Area[SF]
R-Value [hr-SF-[°F/Btu]
U-Value [Btu/hr-[SF-°F]
UA- Value [Btu/hr-°F]
Heat Loss[Btu/hr]
Gross Wall 12,700.0
Window 1,900.0 5.0 0.200 380.0 26,600
Door 0.0 3.0 0.333 0.0 0
Net Wall 10,800.0 33.0 0.030 327.3 22,909
Garage Clg 6,000.0 29.0 0.034 206.9 14,483
Roof 6,000.0 50.0 0.020 120.0 8,400
Total Conditioned Floor Area 19625.0
Ventilation Rate [CFM]
UA- Equiv. [Btu/hr-°F]
Heat Loss [Btu/hr]
Ventilation 900 293.0 20,507
Flr-toFlr Height
[FT]Building Volume
[CF]Infiltration Rate
[ACH]UA- Equiv. [Btu/hr-°F]
Heat Loss [Btu/hr]
Infiltration 10.5 200,000 0.1 361.7 25,317
Building UA-Value 1,689 [Btu/hr-°F]
Building Peak Heat Load 118,215 [Btu/hr]
Load per Ft2 6 [Btu/hr/ft2]9