Sustainable domestic hot water production with heat pumping technologies will become the dominant energy demand in the domestic infra structure offering affordable smart storage opportunities.

Domestic sector energy consumption is mainly concentrated around space heating and hot water demand. Due to new building regulations and energy efficiency measures, in the future, space-heating demands will decrease, by inherently better insulation. But domestic hot water demand will remain relatively constant and can even increase as a consequence of higher comfort demands (e.g. rain-showers) by the end user. Thus due to strict legislation on energy performance domestic hot water is going to dominate the overall energy use in houses, both for the end use in kWh and in capacity.

The objective for the Annex is to analyse the information on hot water heat pumping technologies for the production of sanitary hot water in domestic and other applications. This information will be structured in such a way that leads to better understanding in the market by the end user and policy maker.

The work under the Annex will provide deeper insight into the potential of applying domestic hot water heat pumps using various concepts and systems for new as well as existing buildings by:

  • Reviewing available domestic hot water heat pumps and double function heat pumps making hot water next to space heating and/or cooling.
  • Reviewing the different systems for domestic hot water in their traditional and potential applications and gaining deeper insight in to the use of domestic hot water in order to create a solid basis for test and standardisation procedures.
  • Developing and validating models to enable an objective comparison of domestic hot water heat pumping technologies and other systems.
  • Making an overview of R&D, and sketching a scenario on the needed R&D. This information will be provided to industry players, institutes, and governments with the goal of achieving simple and low-cost solutions.
  • Data basing and where possible monitoring example projects to inform stakeholders of the viability of concepts.
  • Creating a web based information platform to serve countries participating in the Annex by publishing information on their market, legislation and policy.
  • Holding regular workshops
  • Collaborate with other related Annexes within the HPT-TCP or other TCP’s

Project manager and participating countries

Japan,  South Korea, United States, Canada, France, Switzerland and UK. Netherlands is Operating Agent.


The Annex has been structured into the following tasks:

  • Task 1. Market overview, barriers for application
  • Task 2. Systems and concepts in comparison to alternatives
  • Task 3. Modelling calculation and economic models
  • Task 4. R&D
  • Task 5. Example projects and monitoring
  • Task 6. Communication and training

Publication and result

The main objective is to provide deeper insight into the possibilities for implementation and potential reduction of CO2 emissions and energy costs using various domestic hot water heat pump concepts and systems for new as well as existing buildings. This will be achieved by delivering:

  • A scenario for future developments based upon a market analyses
  • A calculation model for the objective comparison of domestic hot water systems and concepts with heat pumps and/or other technologies;
  • Gaining deeper insight into the use of domestic hot water to create a solid basis for test and standardization procedures;
  • A roadmap on Research and Development based upon future market needs;
  • Showcasing existing and new concepts in practice and/or research and where possible supported by monitoring results;
  • Creating a web-based information platform to serve participating countries by publishing information on their market approach and training courses;

The final Annex report will be available for general publication by 2019.

Some relations

An efficient domestic hot water system can be based upon a high performance heat pump. However, the overall system efficiency depends on more than the efficiency of the generator alone. The benefits of an energy efficient generation device like a heat pump can be nullified by poor system integration and large storage or distribution losses. The overall system efficiency is a key point in the development of a Carbon Zero society with a smart energy infrastructure. This makes the choices for the efficient heating of domestic hot water for new buildings and renovation a challenge. Many concepts are still based on the traditional method of installation. For the Nearly Zero Energy new building, the placing of the heat generator can be non-traditional next to the kitchen and / or close to the bathroom. This has a strong relation with the work under HPT-Annex 49.

In the case of the renovation of existing buildings, being the largest market, such a solution is less feasible, and standardized renovation packages should be developed, where some of these are already realized with good examples. For Multi Family Buildings, which is the focus of HPT-Annex 50, the solution can be more complex with existing collective systems for domestic hot water. The replacement of these collective systems by individual domestic hot water heat pumps or semi collective booster heat pumps is one of the many options under survey in the Annex.

In densely populated areas District heating is one of the options often proposed with the 4th Generation in mind. In fact the same option for Multi Family Buildings exist here with a number of examples already given in presentations from typical District Heating countries like Finland. The relation is in this case with HPT-Annex 47.

Other combinations with air-conditioning-systems or solar thermal systems and solar photo-voltaic systems are a possible extension for Annex 46, which is in discussion. The combination with air-conditioning will be an attention point in the new HPT Annex, while the combination with Solar energy is an interesting marketing topic taken into account in Annex 46, broadening the scope and importance of the Annex.

Storage of hot water is one of the basics of a domestic hot water heat pumps, therewith being an important option in a smart grid approach.


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