Room AC energy use is directly related to its British thermal unit (BTU) rating. To find out how much energy your room air conditioner uses, you need to know its cooling capacity, which is expressed in BTUs. If you don’t know your room AC’s cooling capacity, check the unit’s model number plate.
Room air conditioners use about 1 watt of electricity to produce 10 BTUs of cooling. To calculate your room AC’s energy use per hour, divide its BTU rating by 10.
For example, a 14,000 BTU room air conditioner will use about 1,400 watts per hour of energy. If you run that air conditioner for 8 hours every day during a month, it will cost you about $44 on your monthly electric bill, based on an average electricity cost of 12 cents per kWh.
How to Estimate Room AC Energy Use More Accurately
To more accurately estimating room AC energy use, you can use the (combined energy efficiency ratio (CEER) to calculate wattage used per hour. Look for the CEER rating on the model number plate of your room air conditioner. The EnergyGuide® tag also lists the CEER rating.
Divide the BTU rating of your room AC by its CEER rating for the most accurate estimate of energy use per hour.
For example, a 14,000 BTU air conditioner with a 11.3 CEER will use 1,239 watts per hour. Running this air conditioner 8 hours per day for 30 days will cost you $39 on your electric bill.
Room Air Conditioner Energy Saving Tips
Because your room AC uses lots of energy, keep it operating as efficiently as possible. Follow these tips to minimize room AC energy use.
Clean the air filter regularly. Follow the instructions in your owner’s manual when cleaning the air filter. Most manuals recommend that you clean the filter at least monthly. When the filter gets dirty or clogged, the air conditioner works harder to cool the room because not enough air circulates through the evaporator for cooling.
Clean the front grille and case yearly. Unplug the air conditioner and clean the front grille using water and a mild detergent to remove dust and dirt buildup. Wipe the grill with plain water and let the grille to dry completely before using the air conditioner. Wipe dirt and dust off louvers on the case. A clogged grill inhibits airflow through the evaporator so the unit won’t cool efficiently. Blocked case louvers inhibit cooling air flow to the compressor and motor, causing them to work harder and less efficiently.
Clean the condenser and cooling fins yearly. Unplug the air conditioner and use a vacuum cleaner with a soft brush attachments to clean dust and dirt off condenser and cooling fins.
Keeping your room air conditioner clean helps it cool efficiently and last longer.