In our line of work we see all sorts of problems with customers systems. Some are more common than others.

Here are some research findings of astudy by PG&E in 1990. Unfortunately not much has changed.

What Building  Scientists, Researchers, Utilities and Manufacturers Have Discovered.

These studies have been published in various trade journals and are collected here for your information.

Pacific Gas & Electric Study

In the Summer of 1990, Pacific Gas & Electric (PG&E) hired Proctor Engineering Group to investigate the potential energy savings in residential air conditioners and forced air gas furnaces installed in the Fresno, California area. The Fresno study was targeted at PG&E’s high utility bill complaint customers. The objectives of the study were to:

Identify the major problems with existing residential air conditioning installations

Identify the major problems with existing furnace installations

Determine what actions could be taken to correct those problems

Estimate the potential savings from those actions

The results are startling. Here is a summary of their findings:

 

AIR CONDITIONING PROBLEMS

67%

Airflow less than 375 cfm/ton (dry coil)

53%

Coil Dirty or Clogged

40%

Filter Dirty, Clogged or Missing

27%

Refrigerant overcharged (averaged 10% above correct level)

27%

Refrigerant undercharged (averaged 20% below correct level)

20%

Refrigerant leak

20%

Other (Kinked refrigerant lines, wrong capacitor, etc.)
   
 

FURNACE PROBLEMS

60%

Fan Off Temperature above 90º F

60%

Steady-state efficiency less than 75%

27%

Gas leak

13%

Low heat anticipator setting (caused short cycles)

7%

Incomplete combustion (Carbon Monoxide present)

7%

Cracked heat exchanger
   
 

AIR DISTRIBUTION PROBLEMS

93%

Duct leakage greater than 150 cfm (recommended maximum in this study)
   
 

BUILDING SHELL PROBLEMS

33%

House leakier than .75 air changes per hour

93%

No wall insulation

27%

Ceiling insulation less than R-11

13%

Ceiling insulation R-11 to R18.9

The PG&E study identified a significant source of untapped electrical and gas savings. In all cases the cooling energy use could be lowered by 10% to 30% without extreme effort. In addition, these repairs have the potential to improve customer satisfaction.

The Fresno project showed that the existing HVAC contractor infrastructure was not able to identify and solve the problems that led to the high bill complaints. This can be attributed to a business environment that concentrates on low first cost and lowest bid. This business atmosphere results in poor installations and inadequate time available to diagnose and repair extreme problems that exist.