completed special task

Single-Room Heat Pumps for Cold Climates

Air-source heat pump technology used in cold climates generally means limited performance and heating capacity. Efficient defrosting is also required for systems operating in these climates.

In recent years, industry has claimed improvements to single-room heat pumps for cold climates. This project tries to find answers to two questions:

  • What are the real benefits of these improvements in practice? For example, what is the impact of improved part-load efficiency of inverter-controlled air-to-air heat pumps in terms of the Seasonal Performance Factor?
  • What other improvements to single-room heat pumps have been documented? This information could lead to a larger market for single-room heat pumps in cold climates.


The objective of this project is to provide a performance overview of high-efficiency residental single-room heat pumps for cold climates and their practical Seasonal Performance Factor.


The project covers design, performance and installation aspects, and concludes with a brief market analysis. It includes:

  • Heat pump design, including heat exchangers, compressor capacity control (inverter), frost detection, defrost method, defrost control, air-flow control etc.
  • System efficiency and operational experience, with special focus on full-load/part-load efficiencies, reliability and noise level
  • Heat pump system and unit installation, and protection from snowfalls
  • Brief market analysis considering status, economy and projected growth in various cold climate countries

The project focuses on reversible heat pumps for space heating (and cooling) in residential and small commercial applications. Heat pump water heating is not included.


The projects is implemented by the Royal Institute of Technology, Sweden, in collaboration with the IEA Heat Pump Centre.


The project resulted in the following publication:

  • Single-Room Heat Pumps for Cold Climates
    Order the document here

    This report provides an overview of the performance of single-room heat pumps on the market for use in cold climates and focuses on the latest efficiency improvements.