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Department for Business, Energy and Industrial Strategy

Packaged Air to Air Heat Pumps (rooftop)

1.1           Scope

‘Packaged’ type heat pumps are single [1] factory assembled units that incorporate all the elements of the refrigeration system and air distribution mechanisms for space heating, often referred to as ‘rooftop’ due to the most common placement of the product.

Air to air heat pumps are products that are specifically designed to transfer heat from the air in one space into the air within another space by means of a refrigeration cycle.

1.2           Definitions

Packaged Air to Air heat pumps use an electrically operated refrigeration system to transfer heat from air outside a building to the air inside it. They can be used to provide space heating in a wide range of buildings, and some products also are able to provide cooling by reversing the refrigeration cycle (these products are known as reversible ‘air-cooled’ air conditioning units).

Packaged Air to Air heat pumps are available with a wide range of efficiencies. The Energy Technology List (ETL) Scheme aims to encourage the purchase of higher efficiency products.

1.3           Requirements

1.3.1       Eligibility requirements

To be eligible for inclusion on the ETL, products shall meet the requirements as set out below.

To be eligible, products shall:

  • Consist of a single1 factory–built unit.
  • Incorporate an electrically driven refrigeration system that uses a refrigerant which has a maximum Global Warming Potential (GWP) of ≤ 750. 
  • Incorporate all the elements of the air distribution mechanisms for space heating.
  • Be designed for, and include fittings for, permanent installation.
  • Have an appropriate Conformity Assessment mark.

Products shall be designed to primarily supply heating by means of the built-in heat pump and must not incorporate a gas-fired burner, hot water heating coil or steam heating coil.

1.3.2       Performance requirements

Eligible products shall meet the performance criteria set out in Table 1.1 below for:

  • Seasonal Space Heating Energy Efficiency (ηs,h) as defined by Ecodesign Commission Regulation (EU) 2016/2281.
  • Seasonal Space Cooling Energy Efficiency (ηs,c) as defined by Ecodesign Commission Regulation (EU) 2016/2281.

Table 1.1 Performance requirements for Packaged Air to Air heat pumps

Product Category

Heating mode (ηs,h)

Cooling mode (ηs,c)

Packaged Air to Air Heat Pumps (Rooftop)



"≥" means "greater than or equal to"

1.3.3    Information requirements

Supplier shall report the following parameters for each model, which will be published on the ETL Product Search:

  • Whether the model has ‘smart features’. Specifically, this includes the capability to provide information on whether the products are ‘smart ready’ without the replacement or addition of any hardware, which includes the following one or more options:
    1. Demand Side Response Ready
    2. Date Collection Ready, which includes:
      • Storing data on the heat pump or a remote device.
      • The ability to store data for each calendar year as a value per day, per month and per year.
      • The following real time value parameters: electricity energy consumption (kWh); heat delivered (kWh); energy efficiency performance; operating times (days, hrs); number of on/off cycles.
  • The SCOP and SEER for products with an efficiency performance presented in: ηs,h and ηs,c

1.4           Measurement and Calculations

1.4.1       Energy efficiency metrics

Seasonal energy efficiency metrics are used, and should be measured for the ‘Average’ heating season, as defined in Ecodesign Commission Regulation (EU) 813/2013 and the harmonised standard BS EN 14825:2022:

Seasonal Coefficient of Performance (SCOP) - overall coefficient of performance of a heat pump using electricity, representative of the heating season, calculated as the reference annual heating demand divided by annual energy consumption for heating, as defined by BS EN 14825: 2022.

Seasonal Energy Efficiency Ratio (SEER) – overall energy efficiency ratio of a heat pump working in reverse mode for a representative cooling season, calculated as the reference annual cooling demand divided by the annual energy consumption for cooling, as defined by BS EN 14825: 2022.

Seasonal Space Heating Energy Efficiency s,h) – ratio between the space heating demand for reference heating season, supplied by a space heater and the annual primary energy consumption required to meet this demand, as defined by BS EN 14825: 2022.

Seasonal Space Cooling Energy Efficiency s,c) – ratio between the space cooling demand for reference cooling season supplied and annual primary energy consumption required to meet that demand, as defined by BS EN 14825: 2022.

In case of any changes regarding the value of CC in relevant regulations or test reporting procedures, the performance indicators will be calculated using the following equations:

(1)   ηs,h= SCOP/CC -F1

(2)   ηs,c= SEER/CC -F1

Primary energy consumption for electricity usage is obtained using the Conversion Coefficient (CC), known also as the Primary Energy Factor, equal to 2.5, as defined by BS EN 14825: 2022.

Correction factor (F1) is the correction that accounts for a negative contribution to the seasonal space heating energy efficiency of heaters due to adjusted contributions of temperature controls, equal to 3% (BS EN 14825:2022)

Reference heating season, also called climate – is a set of operating conditions describing per bin the combination of outdoor temperatures and the number of hours these temperatures occur for heating for which the unit is declared fit for purpose. There are three reference heating seasons: “A” average, “C” colder and “W” warmer. The UK is located in two reference zones: A and W, but for the ETL purposes “A” for average is to be used.

1.4.2       Test Requirements

No additional testing requirements beyond the measurement standard below.

1.4.3       Measurement standards

Performance data shall be determined and the ηs,h, ηs,c calculated, following the requirements of Commission Regulation (EU) No 2016/2281 and the harmonised standard BS EN 14825:2022, and the specific measurement conditions are set out Table 1.2 below.

Table 1.2 Measurement conditions for Packaged Air to Air heat pumps

Product Category

Heating mode (ηs,h)

Cooling mode (ηs,c)

Packaged Air to Air Heat Pumps

Commission Regulation (EU) No 2016/2281 Co Annex III, tables, 21, 26, average rating conditions  

Rated Capacity (kW):  Commission Regulation (EU) No 2016/2281 Annex III, Table 16

Commission Regulation (EU) No 2016/2281 Annex III, tables 21, 27, average rating conditions,

Rated Capacity (kW):  Commission Regulation (EU) No 2016/2281 Annex III, Table 16

Please note that performance data obtained in accordance with the procedures and conditions laid down in BS EN 14825:2016 and BS EN 14825: 2018 will be accepted as an alternative to testing in accordance with BS EN 14825: 2022 until further notice.

1.4.4       Rounding 

For the avoidance of doubt test data should be presented to zero decimal places for percentage points. As an example, a product with a heating mode ηs,h of 146.4% would be deemed to be a fail.

1.5           Verification for ETL Listing

There are five main ways that applicants can demonstrate their product’s performance:

  • In-house testing – Self-certified
  • In-house testing – Self-tested and verified or cross-checked by an independent body
  • Witnessed testing
  • Independent testing
  • Representative testing (see clause 1.5.1)

Further information regarding the first three routes can be found in the ETL Testing Framework.

1.5.1       Representative Testing

Where applications are being made for a range of products that are variants of the same basic design, test data may be submitted for a representative model, provided that all variants, i.e. models, share following characteristic features:

  • Use the same refrigerant,
  • Have the same compressor type (i.e. manufacturer, line of models), which should imply:
    • same method of compression (e.g. reciprocating or scroll) and
    • same type of enclosure (e.g. hermetic or semi-hermetic),
  • Use the same defrosting method (e.g. hot gas defrost),
  • Are powered using same configuration of inverters.

The representative models may be selected by dividing the range of products into groups of models with similar design characteristics. The performance of each model shall be predicted using a validated mathematical model. At least one model in each group shall be tested for validation purposes. A report documenting performed model calculations, showing all significant calculation steps, shall be submitted with the application.

It should be noted that:

  • If a manufacturer voluntarily removes the representative model from the ETL then other products linked with that representative model may or may not be permitted to remain on the ETL.
  • If any product submitted under these representative model rules is later found not to meet the performance criteria when independently tested, then all products based on the same representative model will be removed from the ETL.

1.6           Conformity testing

Products listed on the ETL may be subject to the scheme’s conformity testing programme in order to ensure listed models continue to meet the ETL requirements.

1.7           Review

1.7.1       Indicative review date

The next technical review is scheduled for 2025-26.

1.7.2       Illustrative future direction of the requirements 

Future changes to the specification may include:

  • Increasing performance thresholds for ηs,h and ηs,c
  • Updating the product eligibility and functionality requirements as per market demand and any UK or EU regulatory changes. 
  • The possibility of ‘smart features’ becoming an eligibility requirement for listed packaged air to air heat pumps. 
  • The possibility of updating the product eligibility requirements to encompass embodied lifetime carbon of heat pumps. Introducing a maximum value (measured in tonnes/ CO2) for the lifetime carbon of a heat pump.


[1] As per Ecodesign guidelines single package should be interpreted as “a unique functional unit that is provided by one manufacturer with one single commercial reference. However, this assembly can be provided on one or two separate frames”.