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What's the Difference Between SEER, EER and CEER?

Do you love having air conditioning but wish it weren't so costly to run during an Ontario summer? Who doesn't! Our province generally has mild summers, but some days call for AC. There's no question that air conditioning is a luxury for Ontarians. If you buy a  unit with a high SEER, EER, or CEER rating, though, the energy savings might pay you back in time—especially if you maintain it well. We'll discuss the SEER and EER ratings you see where HVAC equipment is for sale, what each acronym refers to, and how the numeric ratings can help you select the best model for your needs.

About SEER, EER, and CEER

Both SEER and EER are energy efficiency ratings. Both are mandatory and held to standards set in place by the Canadian government. The Energy Efficiency Regulations that apply to air conditioning began in 1995.

SEER (Seasonal Energy Efficiency Ratio)

SEER measures the cooling efficiency of an air conditioner over an entire cooling season. A SEER is based on a climate with an average summer temperature of 28°C. To determine a SEER:

  1. Multiply the number of BTUs/hour by 1,000.

  2. Multiply the number of watts used/hour by 1,000 to find the total number used in an average season.

  3. Find the SEER by dividing the number of BTUs by the watts used in a season. In high-efficiency whole-home models, SEER can be over 20, with less efficient models starting at 13 (the lowest SEER sold today).

EER (Energy Efficiency Ratio)

EER measures how much cooling effect the air conditioner provides for each unit of electrical energy it consumes while operating in a steady-state. You can calculate an EER by dividing the unit's cooling output in BTUs/hour by the electrical power input in watts at a given temperature.

CEER (Combined Energy Efficiency Ratio)

CEER is a rating introduced in 2014 to better estimate the realistic energy-efficiency of a window or room air conditioner. It measures the combined efficiency of the unit both in standby mode and when cooling. CEER helps determine the air conditioner size you need for a single room (i.e., BTU output). So, be sure to compare only other units with comparable output levels when looking at the CEER rating on the label.

How Do the Three Ratings Differ?

SEER generally applies to central AC units and heat pumps, whereas EER and CEER (recently introduced in Canada) are more typical of window units. SEER predicts energy efficiency for an entire cooling season, so the efficiency of the AC is measured at air temperatures from 18.3 to 40°C. In contrast, EER determines energy efficiency at a single air temperature, 35°C. SEER is measured at various temperatures. That means it speaks to the AC's starting and stopping cycle. And since EER is measured at a high temperature, it accounts for the AC running all the time (steady-state).

Benefits of High SEER, EER, or CEER Ratings

If a central AC unit has higher energy efficiency ratings (e.g., SEER) across the board, it might be ENERGY STAR certified and use less energy than traditional units. When shopping for AC (or other HVAC equipment), pay close attention to any energy efficiency labels you see on the display units. If you can't find the tags, ask for help. Doing so could save money and help the ecosystem. As your HVAC company in south-central Ontario, Aire One Heating & Cooling can help you find the air conditioning unit that's right for your home, budget, and comfort. Forego the big box stores. Contact Aire One Heating & Cooling in Kitchener-Waterloo for advice from the pros!


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