Reducing the Cooling – Heating Load

If you follow our recommended sequence and prepare a heat gain/loss calculation on your home first, you have the baseline to perform additional analysis.  Many contractors use load calculation simulation software similar to Writesoft .  Using a simulation programbasic data is entered and “what-if analysis“ can be performed at the push of a button.  Otherwise some simple addition and subtraction will be required.

The first consideration should be improving the building envelope to reduce heat gain/loss and the size air conditioner / heater needed. 

Consider the following:

  • Ceiling insulation.  Use an R-38 or higher insulation.  Many existing homes have R-19 in the ceiling.  Calculate savings based on the BTU’s per square foot difference.  Reduce the size of the unit required and reduce operating cost.  Investing in insulation with a 30 year life that does not use any energy or require maintenance vs. an air conditioner with a 14 year life is probably a good investment.
  • Wall insulation might not be an option in an existing home. Do the analysis to decide.
  • If ductwork will be installed in an attic, consider insulating the roof with spray foam.  This places the ductwork is in a conditioned space where leaks and losses from ducts don’t increase the load.  Foam in the roof also eliminates most of the infiltration from penetrations in the ceilings due to light fixtures, wire, ducts etc. 
  • Consider a ductless air conditioning system.
  • Consider an energy recovery ventilator.  This device recovers much of the energy from exhausted air and transfers it to incoming fresh air for ventilation.
  • Use actual infiltration data instead of statistical data.  Perform a blower door test on the structure to locate and seal unwanted outside air leaks.  Measure the actual infiltration for use in sizing the air conditioning system.
  • Use ducked returns to eliminate losses in walls and ceilings.
  • Consider white or reflective roofing.
  • Consider high efficiency lighting.  Lighting produces heat that must be removed by the AC.