TYPICAL HEATING & COOLING LOADS in Older Homes

HOUSE TYPES (updated 10/2013) The following three house types and their corresponding typical heating and cooling loads are intended to serve as a rule of thumb only and as all such rules, wide variations can be experienced. In order to establish the basis for comparison the following assumptions were made: 2,100 SF house; finished basement; first floor-ground protected basement front with walk-out rear; heating design differential of 60°{outdoor 10° F & indoor 70° F); cooling design differential of 20° F (outdoor 95° F and indoor 75° F); the front of the house facing due south.

T Y P E " A " This house type is typical of houses that are 10 to 25 years old. Following are the parameters for the calculations:

• Insulation: R-19 walls with direct exposure; R-30 attic; R-8 on basement walls above grade.
• Window Type: Wood dual-glazed 'insulated glass'
• Window/Wall Ratio: 13% of wall area is for windows and doors
• Infiltration Rate: 1.0 Air Change Per Hour (ACH)
• HEATING LOADS: 18 to 22 BTUH/ Square Foot
• COOLING LOADS: 9 to 12 BTUH/ Square Foot

T Y P E " B " This house type is typical of houses that are 25 to 40 years old. Following are the parameters for the calculations:

• Insulation: R-13 walls with direct exposure; R-l9 attic; no insulation on basement walls.
• Window Type: Aluminum single glazed with storm windows
• Window/Wall ratio: 18% of wall area is for windows and doors
• Infiltration rate: 1.5 Air Change Per Hour (ACH)
• HEATING LOADS: 25 to 30 BTUH/ Square Foot
• COOLING LOADS: 15 to 17 BTUH/ Square Foot

T Y P E: " C " This house type is typical of houses greater than 40 years old. Following are the parameters for the calculations:

• Insulation: Minimal to none in walls with direct exposure; composite average R-6; R-11 in attic; no insulation on basement walls.
• Window Type: Wood single glazed with no storm windows
• Window/Wall ratio: 22% of wall area is for windows and doors
• Infiltration rate: 2.5 Air Change Per Hour (ACH)
• HEATING LOADS: 45 to 53 BTUH/Square Foot
• COOLING LOADS: 19 to 25 BTUH/Square Foot

If the home to be analyzed has parameters higher or lower then the ones shown here, just raise or lower the final figures accordingly. These represent the norm, older houses with loose construction techniques will experience higher heat losses as the outdoor wind speed also increases.

Note: 12,000 BTU = 1 ton of AC

CONVERSION CHART from KWH to BTUH
(3412 BTUH = 1 KWH)
AMPS @ 240 Volts