Conversion Formulas
COP = EER / 3.412
kW/ton = 3.517 / COP
COP = 3.517 / kW/ton
All conversions are single-point (instantaneous), not seasonal averages.
COP / EER / kW-per-Ton Equivalence Table
| COP | EER | kW/ton | Efficiency Tier |
|---|---|---|---|
| 2.0 | 6.8 | 1.76 | Low -- older or entry-level equipment |
| 2.5 | 8.5 | 1.41 | Below average |
| 3.0 | 10.2 | 1.17 | Average residential heat pump |
| 3.5 | 11.9 | 1.00 | Good residential efficiency |
| 4.0 | 13.6 | 0.88 | Good to very good |
| 5.0 | 17.1 | 0.70 | Excellent -- common quality chiller COP |
| 6.0 | 20.5 | 0.59 | Very high efficiency chiller |
| 7.0 | 23.9 | 0.50 | Premium high-efficiency chiller |
Equipment Efficiency Reference by Type
| Equipment Type | Typical COP Range | Typical EER Range | Notes |
|---|---|---|---|
| Window room A/C | 2.5 - 3.3 | 8.5 - 11.3 | Small, less efficient by design |
| Residential split A/C | 3.0 - 4.3 | 10.2 - 14.7 | Standard efficiency to high efficiency |
| Residential heat pump (heating) | 2.5 - 4.0 | 8.5 - 13.6 | Varies significantly with outdoor temp |
| Cold-climate heat pump (at -15°C) | 1.8 - 2.5 | 6.1 - 8.5 | Rated at cold-weather test point |
| Ground-source heat pump | 3.5 - 5.0 | 11.9 - 17.1 | Ground loop stabilizes performance |
| Air-cooled chiller (standard) | 2.8 - 3.5 | 9.6 - 11.9 | Common commercial chiller range |
| Water-cooled chiller (standard) | 4.5 - 6.0 | 15.4 - 20.5 | Higher efficiency due to cooler condensing |
| Water-cooled chiller (high-efficiency) | 6.0 - 8.0 | 20.5 - 27.3 | Premium centrifugal or magnetic bearing |
These are single-point (instantaneous) efficiency values at specific test conditions, not seasonal averages. For seasonal metrics like SEER and HSPF, use the SEER / COP / HSPF Converter. Actual field performance varies with outdoor conditions and load.
How to Use the COP to EER Converter
Type a value in COP, EER, or kW/ton. All other units update instantly. Use the quick presets to load common efficiency benchmarks: COP 3.0 to 5.0 for typical heat pump and chiller ranges, EER values matching common North American equipment labels, or kW/ton for commercial chiller comparisons.
The result panel identifies what efficiency tier your value falls in, from low-efficiency older equipment through premium high-efficiency chillers. This helps confirm a converted value is realistic for the equipment type you're comparing.
Use the converter to translate a European manufacturer's COP rating into the EER format shown on North American equipment labels, or vice versa. This lets you compare imported or specialty equipment directly against locally available options on a common efficiency basis.
The equivalence table shows matched COP, EER, and kW/ton values across the full efficiency range. The equipment type table shows typical ranges for window units, residential heat pumps, cold-climate heat pumps, and commercial chillers. For seasonal efficiency metrics like SEER and HSPF, use the SEER / COP / HSPF Converter instead, since those represent averages across a full season rather than a single test point.
COP and EER -- Understanding Single-Point Efficiency
COP (Coefficient of Performance) and EER (Energy Efficiency Ratio) both measure instantaneous HVAC efficiency at a specific operating condition -- unlike SEER and HSPF, which represent seasonal averages across a range of conditions. Understanding the difference and converting fluently between metrics is essential when comparing equipment from different regions or evaluating manufacturer performance data at specific design conditions.
COP -- The Dimensionless Ratio
COP is simply output divided by input, both in the same units (typically watts): COP = cooling or heating output (W) / electrical input (W). A COP of 4.0 means 4 watts of heating or cooling delivered per watt of electricity consumed. Because it's dimensionless, COP is the standard metric in SI-based engineering and appears on European and international equipment datasheets. COP applies equally to heating and cooling -- a heat pump has a separate COP rating for each mode. Natural Resources Canada's heat pump guide walks through how COP and the other efficiency metrics relate to real-world performance.
EER -- The Imperial Mixed-Unit Metric
EER expresses cooling output in BTU/hr divided by electrical input in watts: EER = cooling output (BTU/hr) / input power (W). Since 1 watt equals 3.412 BTU/hr, EER and COP are related by that same factor: EER = COP x 3.412. A COP of 3.5 converts to an EER of 11.9. EER is standard on North American cooling equipment labels and is always a cooling-only metric -- there's no "heating EER" equivalent, since heating efficiency uses COP or HSPF instead. ENERGY STAR's glossary defines EER this same way, as cooling output in Btu/hr per watt of input.
kW/ton -- The Commercial Chiller Metric
Commercial chiller specifications frequently use kW/ton, which is the inverse relationship: kW/ton = 3.517 / COP. Lower kW/ton means higher efficiency (less electrical power needed per unit of cooling). A chiller rated 0.6 kW/ton has COP = 3.517/0.6 = 5.86 -- a very efficient chiller. This metric is popular in commercial engineering because it directly indicates electrical demand, useful for utility load calculations and electrical service sizing. The Chiller Load Calculator uses this same kW/ton relationship when sizing commercial cooling plants.
Why This Matters for Canadian HVAC
Canadian HVAC professionals regularly encounter equipment from European, Asian, and North American manufacturers, each using their region's preferred efficiency metric. A German ground-source heat pump might list COP 4.5; a comparable North American unit might list EER 15.4 -- these represent nearly identical instantaneous efficiency once converted (4.5 x 3.412 = 15.35). Being able to convert quickly prevents misjudging one manufacturer's equipment as more or less efficient than it actually is, simply because of unit presentation differences. Use the SEER / COP / HSPF Converter for the seasonal (rather than single-point) efficiency comparison that matters most for actual annual energy cost estimation with the Annual Energy Cost Calculator.
Frequently Asked Questions
Multiply COP by 3.412 to get EER. So COP 3.5 = EER 11.9, and COP 4.0 = EER 13.6. To go the other way, divide EER by 3.412. This factor comes from the fact that 1 watt equals 3.412 BTU/hr -- COP is a dimensionless watt/watt ratio while EER measures BTU/hr of cooling per watt of input. Both describe the same instantaneous efficiency, just in different unit conventions.
For mild Canadian climates (coastal BC, southern Ontario), a rated heating COP of 3.0 to 4.0 at standard test conditions is good. For cold-climate heat pumps rated for operation to -25°C or below (needed in the Prairies and northern regions), a COP of 2.0 to 2.5 at the coldest rated temperature is considered good, since COP naturally drops as outdoor temperature falls. Always compare COP at the specific outdoor temperature relevant to your climate, not just the standard rating point of 8.3°C.
COP measures output per unit input (higher is better); kW/ton measures input per unit of cooling delivered (lower is better) -- they're inversely related. The conversion: kW/ton = 3.517/COP. A chiller with COP 5.0 has kW/ton = 0.703. Commercial chiller specs commonly use kW/ton because it directly shows electrical demand per ton of cooling, useful for electrical load and utility demand calculations.
European datasheets typically use COP (a dimensionless SI-consistent ratio); North American datasheets use EER or SEER (BTU/hr per watt, based on Imperial thermal units). A European heat pump at COP 4.0 and a North American unit at EER 13.6 have essentially identical instantaneous efficiency once converted (13.6/3.412 = 3.99 COP). Always convert to a common metric before comparing international equipment to avoid misjudging relative efficiency due to unit presentation alone.