Home Heating Myths

1
Home Heating Myths

• CREF Meeting
• August 11, 2008

2
Home Heating Energy Use

• Climate
• Heating Degree Days
• Thermal losses
• Heating unit type
• Fuel heat content
• Seasonal efficiency
• Energy Use and Cost

3
Heating Degree Days

• Albany, New York 6,888 _at_ 65 F base

4
Thermal Losses

• Size of structure
• Thermal envelope
• Infiltration
• Orientation

5
Heating Unit types

• Forced Air furnace
• Hot Water boilers
• Steam boilers
• Electric resistance units
• Heat Pumps

6
Fuel Content

• 2 Fuel oil, 141,000 btu/gallon
• Natural gas, Therm 100,000 btus
• Electricity, 1 kwh 3413 btu/hr

7
Seasonal Efficiency

• Manufacturer Efficiency is not the same as
  seasonal efficiency
• A conventional fuel oil fired forced air furnace
  that is over ten years old may have a
  manufacturer efficiency of 85.
• Assume it is installed in a home that has a
  heating load of 56,000 Btu/hr
• Then,

8
Seasonal Efficiency

• It is likely that the unit was oversized to
  insure that it would always meet heating demand.
  A typical case is where the unit would be 120,000
  Btu/hr input.
• The unit will start and stop more frequently due
  to being oversized.
• Outcome, Seasonal efficiency is lower

9
Energy Use

• Energy Use
• U x A x HDD/yr x 24 hr/day
• ________________________
• Seasonal efficiency x heat value

10
Energy Use

• Example with SE 0.6
• 1755 Btu/h/F x 6,888 HDD/yr x 24
• __________________________
• 0.6 x 141,000 Btu/gal
• 3429 gallons/yr

11
Energy Use

• Example with SE 0.8
• 1755 Btu/h/F x 6,888 HDD/yr x 24
• __________________________
• 0.8 x 141,000 Btu/gal
• 2572 gallons/yr

12
Energy Cost

• Energy use with SE 0.6
• 3,429 gal/yr
• Fuel oil at 3/gal
• Cost is 10,287 yr
• Fuel oil at 5 gal
• Cost is 17,145

• Energy use with SE 0.8
• 2,572 gal/yr
• Fuel oil at 3/gal
• Cost is 7,716 yr
• Fuel oil at 5 gal
• Cost is 12,860
• Savings 4,285/Yr