the 2030 challenge & current energy efficient housing

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

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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


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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


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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

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Portland Maine Project Petersen Engineering 2007

Proposed Case 1 - Increased R-values/Decreased Infiltration





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



Heat Loss [Btu/hr]

Ventilation 900 293.0 20,507

Flr-toFlr Height

[FT]Building Volume


[ACH]UA- Equiv.

[Btu/hr-°F]Heat Loss

[Btu/hr]

Infiltration 10.5 200,000.00 0.2 723.3 50,633





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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


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Portland Maine Project Petersen Engineering 2007

Proposed Case 2 - Increased R-values/Very Low Infiltration/Best Windows/Reduced Window Area





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



Heat Loss [Btu/hr]

Ventilation 900 293.0 20,507

Flr-toFlr Height

[FT]Building Volume


[ACH]UA- Equiv. [Btu/hr-°F]

Heat Loss [Btu/hr]

Infiltration 10.5 200,000 0.1 361.7 25,317





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James Petersen P.E.Petersen [email protected]

the 2030 challenge & current energy efficient housing

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