Air Conditioner Costs &
Heat Pump Operating Costs

How to actually calculate HVAC operating costs

500 kWh used per season x $ 0.25 = $125.00 - that's your electricity cost to run the air conditioner for a season.

How Much Does It Cost Per Hour to Run An Air Conditioning System

This is an even simpler calculation. Using as an example information from our example air conditioner's data tag,

((5000 BTUH) / (10 SEER)) = 500 Wh

500 Wh x $ 0.25 = $0.12 per hour to run our air conditioner. Twelve cents per hour is your hourly cooling cost to run your A/C.

Paul Presson, R.A. notes: "Correct the cost per operating hour calculation - the $0.25/kwh needs to be divided by 1,000 to get the watt hour cost."

Other Equations Using SEER Ratings

We can also write the SEER equation shown above as:

SEER = BTUs / Watt-hours
where "watt-hours" = (number of hours of system operation) x (watts used per hour)

...

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Comments: divide kwh by 1000 to get watt-hour cost.

Appreciate the info.

Correct your cost per operating hour calculation to note the $0.25/kwh needs to be divided by 1,000 to get the watt hour cost. (June 26, 2014) Paul A. Presson, R.A

Reply:

Thanks so much, Paul.

 

Question: How Can I Reduce the Operating Cost and Energy Consumption of my Air Conditioning & Heat Pump System?

As we discussed at POST a QUESTION or COMMENT about the Energy Star Program's SEER and EER definitions and equipment ratings,

Answer: List of Air Conditioning & Heat Pump System Steps or Installation Details that Save on Operating Cost

According to SoCalEdison's "Comprehensive Packaged Air Conditioning Systems", Residential and commercial air conditioning is responsible for the largest share of peak demand in California, contributing approximately 33% of peak demand. < [3] [4]

Saving money on central or even portable air conditioners and heat pumps starts by buying equipment with a high SEER (Seasonal Energy Efficiency Ratio (SEER)) rating. But as SoCalEd points out [4] , the purchase of high efficiency (high SEER) HVAC equipment captures only a small part of the total savings in air conditioning or heat pump costs that could be saved by other installation and maintenance steps that we outline here [quoted, paraphrased, and expanded from [4] ]:

Proper Sizing of the Air Conditioner.

Supporting proper sizing in residential and commercial units can yield savings. Contractors frequently install oversized systems to avoid potential comfort and call back risks. See CO

OLING CAPACITY, RATED, and also, because an oversized air conditioner is likely to fail to adequately dehumidify building air, also

see A/C Not Dehumidifying.

[Air Conditioner & Heat Pump] Refrigerant Charge and [compressor/condenser] Airflow.

Between half and three-quarters of all packaged air conditioning units suffer from incorrect charge and low airflow. For both new and existing equipment, ensuring the proper refrigerant charge and airflow can increase efficiency. [5]

See REFRIGERANT GASES & PIPING and

see REFRIGERANT LEAK DETECTION where we describe types of A/C refrigeration system leaks, where they occur, and how they damage the system.

Also see REFRIGERANT LEAK REPAIR. [We {DF] speculate that this problem may be more severe for residential air conditioners and heat pumps than for those commercial units whose design includes a refrigerant receiver.]

[HVAC Air] Duct Sealing.

Ensuring tight ducts in residential and commercial installations yields 10- 18% energy savings.6 The peak load reduction can be higher, yielding a demand savings of 25%.[ 4< and citations therein]

See our articles on air duct leaks:
  
LEAKY DUCT CONNECTIONS
    
Leaky or Missing Air Ducts

    Hidden Missing Air Conditioner Duct

    Duct Retrofit Leaks

    Rooftop Duct Leaks

    RETURN DUCT AIR LEAKS

    SUPPLY DUCT AIR LEAKS

In our [DF] OPINION in addition to sealing duct leaks, better attention to balancing the quantity of return air available to the air handler with the supply duct and register system is needed at many buildings. See RETURN AIR, INCREASE

In our [DF] OPINION, the most basic homeowner maintenance task that can reduce air conditioning and heat pump operating tasks is to be sure that air filters are in place, properly selected, sized, installed, not leaky, and that the filters are changed on a regular schedule.

See DIRTY AIR FILTER PROBLEMS and

see AIR FILTERS for HVAC SYSTEMS for details. Also see our suggestions

at AIR FILTERING STRATEGIES.

HVAC Economizers.

Research shows that the majority of [HVAC] economizers do not function as intended. Use of the Whole Building Diagnostician tool in new and existing buildings in California has confirmed that problems with outside air economizers are endemic. The potential savings from fixing a malfunctioning economizer are approximately 10 – 15% of total packaged air conditioning load. In addition, enabling damper function is a prerequisite for further savings from demand controlled ventilation. [4 and accompanying citation]

Definition of Economizer for HVAC systems:

economizers are devices designed to reduce the operating cost (and energy used) in mechanical systems, principally by re-using heat (or cooling) already produced within the system. Examples of economizer designs in HVAC systems include details that may be found both at the ductwork / air handling system (this is the common use of "economizers on

HVAC systems) and also right inside of the compressor/condenser unit (a technical use of HVAC economizer heat exchange theory):

• Air-to-air heat exchangers 
  
  that heat incoming fresh air (makeup air) being introduced into the duct system during the heating season by using the heat from combustion exhaust or other sources.
• Refrigerant tubing co-soldering 
  
  of the high pressure (high temperature or "high side") refrigerant piping alongside of low pressure (low temperature or "low side") tubing at certain locations in the air conditioning or heat pump system to improve system efficiency. We explain this A/C or heat pump refrigerant line soldering/brazing detail
  
  at REFRIGERANT PIPING INSTALLATION - at the
  
  subtopic: Technical Note on Refrigerant Piping: HVAC economizer detail
• HVAC Controls.
  
  Appropriate controls which enable variable heating and cooling conditions based on occupancy are also critical. With a comprehensive program to address all of these opportunities, the savings per packaged air conditioning unit easily approach 20 percent. [4]

...

Continue reading at SEER RATINGS & OTHER DEFINITIONS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ENERGY SAVINGS in BUILDINGS
• SEER RATINGS & OTHER DEFINITIONS

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OPERATING COST, AIR CONDITIONER at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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Citations & References

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