Introduction
When comparing air conditioners or heat pumps, you will often encounter two indicators: EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio). These two measures are central to evaluating a unit’s energy efficiency, but they do not mean the same thing and are not interpreted in the same way.
Fully understanding the difference between these two indices helps you better anticipate the real electricity consumption of an air conditioner or a heat pump. It also helps you choose a unit suited not only to the size of the home, but also to the specific climate conditions of a region like Quebec.
Summary of Key Points
- EER measures a unit’s energy performance under fixed, one-time conditions.
- SEER calculates average efficiency over an entire cooling season.
- EER is based on an outdoor temperature of 35 ºC and an indoor temperature of 26 ºC with 50% humidity.
- SEER factors in temperature variations and provides a more realistic view of annual efficiency.
- In a hot, stable climate, EER remains a good indicator, whereas in Quebec SEER is more representative.
- Modern energy labels mainly display SEER to guide consumers.
- A higher SEER means less energy consumed for the same comfort.
- Reading EER, SEER, COP, and SCOP together allows for a more informed choice for heat pumps.
What is EER?
Definition
EER (Energy Efficiency Ratio) is an instantaneous energy performance indicator. It measures the ratio between the cooling output delivered by the unit and the electrical energy consumed, under standardized conditions.
For example, an air conditioner with an EER of 3 produces 3 kW of cooling for each kW of electricity consumed. This ratio makes it possible to compare different models without being influenced by other variables such as weather or usage habits.
Calculation Conditions
The calculation is based on precise conditions:
- Outdoor temperature of 35 ºC (95 ºF).
- Indoor temperature of 26 ºC (78 ºF).
- Relative humidity of 50%.
These parameters reproduce a typical extreme heat scenario, but one that is still occasional. As such, EER provides useful but limited information, because it does not account for the temperature variations found over an entire season.
Practical Example
A wall-mounted air conditioner that consumes 1.5 kW to deliver 4.5 kW of cooling capacity has an EER of 3. This makes it possible to quickly compare two units tested under the same conditions, without considering climate variability. Even if this method may seem simplistic, it remains valuable for judging a unit’s immediate ability to be efficient.
What is SEER?
Definition
SEER (Seasonal Energy Efficiency Ratio) is a more modern and representative measure. Unlike EER, it is not limited to a one-time test. It calculates the overall efficiency of an air conditioner or a heat pump over an entire cooling season, incorporating variations in temperature and humidity.
This approach offers a more realistic perspective for consumers, because it aligns more closely with day-to-day use of a unit over several summer months.
Calculation Conditions
SEER is calculated by considering:
- A fixed indoor temperature (26 ºC).
- Outdoor temperatures ranging from 15 ºC (60 ºF) to 37 ºC (100 ºF).
- Operating periods at partial load (closer to real-world use).
Thanks to this approach, SEER reflects a unit’s ability to remain efficient in various weather situations, which is why it is increasingly used by manufacturers and standards organizations.
Reading an Energy Label
Modern air conditioners display their energy class based on SEER. The higher the number, the more efficient the unit. The best models now reach values above 20, while a value of 14 or 15 is considered acceptable for residential use. This figure, combined with a clear energy class (from A to A+++), greatly simplifies reading for consumers.
Key Differences Between EER and SEER
The table below summarizes the major distinctions:
| Criterion | EER | SEER |
| Type of measurement | Instantaneous | Seasonal |
| Conditions | Fixed temperature (35 ºC outdoor / 26 ºC indoor) | Variable temperatures (15 ºC to 37 ºC) |
| Usefulness | Hot, stable climate | Variable climate (like Quebec) |
| Reading | One-time performance | Average annual performance |
In practice, EER remains useful for comparing units under extreme conditions. But SEER provides a more realistic view of energy performance in day-to-day contexts. They are therefore two complementary tools that should be read together to obtain a more complete assessment.
How are EER and SEER calculated?
Calculating EER
EER is obtained by dividing the cooling output delivered (in BTU/h or kW) by the electrical consumption in watts.
- Example: an air conditioner rated at 12,000 BTU/h that consumes 1,200 W has an EER of 10.
This quick calculation makes EER accessible and easy to compare, even if its usefulness remains limited to laboratory conditions.
Calculating SEER
SEER divides the total cooling produced over a season (in BTU) by the total electrical energy consumed (in Wh).
- Example: if an air conditioner produces 60,000 BTU over a season and consumes 5,000 Wh, its SEER is 12.
This approach requires more data, but it provides a reading that more closely reflects what the user will see on their electricity bill.
Practical Comparison Between Two Air Conditioners
Let’s take two models:
- Air Conditioner A: SEER = 23.
- Air Conditioner B: SEER = 14.
The first is about 40% more efficient than the second. In concrete terms, this means it uses much less electricity to provide the same level of comfort, which translates into significant savings over the unit’s lifespan. These numerical differences help consumers understand how directly SEER affects their annual consumption.
Impact of Climate on Interpretation
The role of EER in hot, stable climates
In regions where the temperature remains constantly high and dry (arid or desert climates), EER is often sufficient to judge performance. It accurately reflects efficiency in conditions that change little throughout the year. In these contexts, the one-time value is more representative than in regions with changing conditions.
The importance of SEER in Quebec
In Quebec and most Canadian regions, summer temperatures fluctuate widely. SEER is therefore a much more relevant indicator, because it takes these variations into account and better reflects real consumption over the whole season. In other words, choosing an air conditioner based on EER alone could be misleading, whereas SEER is closer to users’ real-world experience.
Energy Rating and Reading Labels
Classes for EER
Historically, EER was associated with a ranking from A to G, but this approach is used less and less. It remains useful for understanding how standards have evolved, but it tends to be replaced by SEER in most modern catalogues.
Classes for SEER
Today, it is SEER that defines modern energy classes. Units are ranked from G (not efficient) to A+++ (very efficient). This simplifies reading for consumers and encourages the purchase of more efficient models. This classification also has the advantage of harmonizing practices across different countries, making it easier to compare products.
Practical Tips for Choosing Well
- Always cross-reference EER and SEER: the first gives an idea of performance in extreme heat, the second reflects annual efficiency.
- Also check COP and SCOP: for heat pumps, these indices complete the assessment in heating mode.
- Consider the climate: in Quebec, a high SEER is a major asset.
- Do not neglect installation: a high-performing unit can lose much of its efficiency if it is poorly sized or poorly installed.
- Plan regular maintenance: filters, coils, and refrigerant directly influence real-world efficiency.
These tips are a reminder that the number alone is not enough: a good choice depends on a global approach that combines intrinsic performance, climate suitability, and quality commissioning.
Summary Comparison Table: EER vs SEER
| Aspect | EER | SEER |
| Measurement | Instantaneous | Seasonal |
| Test conditions | 35 ºC outdoor, 26 ºC indoor | 15 to 37 ºC outdoor, 26 ºC indoor |
| Relevance | Hot, stable climate | Temperate, variable climate |
| Representativeness | One-time situation | Average annual performance |
| Current reading | Used less often | Main standard on energy labels |
This table summarizes the main differences and helps visualize the complementarity between the two indices at a glance.
Daikin Québec and Energy Efficiency
Air conditioners and heat pumps distributed by Daikin Québec display high SEER values designed to deliver stable performance in Quebec’s climate conditions. By considering both SEER and EER, consumers can choose a unit that maximizes both indoor comfort and energy efficiency. This combination is particularly important for Quebec households, which must deal with variable summers and differing cooling needs from one year to the next.
Conclusion: Two Complementary Indices
EER and SEER are two different but complementary measures. The first offers a snapshot of instantaneous performance, while the second provides a realistic, representative view of efficiency over an entire season.
By correctly interpreting these two indices and combining them with other factors such as COP or SCOP for heat pumps, Quebec consumers can make informed decisions. To benefit from tailored advice and choose a reliable system, you can rely on the expertise of Daikin Québec.
Frequently Asked Questions About EER and SEER
What is the difference between EER and SEER?
EER measures an air conditioner’s energy efficiency under fixed conditions, whereas SEER assesses performance over an entire season. SEER is therefore more representative of real use, especially in climates like Quebec’s where temperatures vary.
Which index is most important for choosing an air conditioner?
In regions with changing climates, SEER is generally more useful. It reflects average performance over several months, while EER remains helpful for comparing efficiency during very hot days.
What is a good SEER for a residential unit?
A SEER of 14 to 16 is considered acceptable for standard residential use. High-end models often reach values above 20, which can significantly reduce electricity consumption while maintaining indoor comfort.
Is EER still used today?
Yes, but it is less common than SEER on modern labels. It remains relevant for evaluating performance in very hot, steady climates, such as in the southern United States or some arid regions.
Why is SEER more relevant in Quebec?
Because summer temperatures vary greatly from one day to the next. SEER incorporates these fluctuations and therefore provides a more realistic picture of the real electricity consumption of an air conditioner or a heat pump in a temperate climate.
Does SEER have an equivalent for heating?
Yes. For heating mode, COP and HSPF are used. These two indices measure a heat pump’s energy performance when heating rather than cooling.
