IEA HPT Annex 61: Heat Pumps in Positive Energy Districts

IEA HPT Annex 61 evaluates the role of heat pumps (HP) in positive energy districts (PED). Efficiency potentials of the electric and thermal energy of districts that can be unlocked with the use of HPs are evaluated in order to reach a positive energy balance. This refers to both, upgrade of waste heat and simultaneous generation of different energy use in buildings (space heating, DHW, space cooling/dehumidification) and includes self-consumption of on-site renewable electricity generation.

Short Description

The building sector plays a key role in reducing CO2 emissions and thus the climate protection goals. Districts offer the potential to further increase efficiency through dedicated solutions for different building uses and load patterns, which can offer synergies on both the electric and the thermal side.

The overarching goal of Annex 61 is to assess the role of heat pumps (HP) in Positive Energy Districts (PED). In particular, the efficiency potential of districts that can be unlocked through the use of HP with the aim of achieving a positive energy balance should be identified.

Annex 61 builds on the work of Annex 49 on the design and integration of HP in so-called nearly zero energy buildings (nZEB). HP show high efficiency in connection with on-site renewable energy production, but for larger buildings and building clusters it is still a challenge to achieve a positive energy balance. Potentials can result from the combination of existing and new buildings, for which strategies will be developed in Annex 61.

In PED, the buildings become net energy producers and thus an active part of the energy system. At district level, HP are a key technology for sector coupling and thus for linking the heating and cooling demands with electricity generation and for integrating renewable energies.

Several actors are involved in the development of new concepts for PED. Manufacturers develop components and system solutions for integration in buildings or groups of buildings and further at district level. Politicians need information on how the energy transition can take place at district level, both for newly built and existing districts. Planners/designers as well as engineering and construction companies need information for their buildings in order to establish innovative concepts at district level to meet ambitious political energy and emission targets.

In order to achieve the goals of Annex 61, the activities are divided into five tasks.

State of the art of heat pump applications in Positive Energy Districts: The state of the art of Positive Energy Districts and heat pump applications is examined through literature research, both for new and existing projects and at building and district level.

Creation of different heat pump concepts at individual building and quarter level: This includes the simulation-based analysis and evaluation.

Technical and economic evaluation of heat pump concepts for individual buildings and districts: Heat pump concepts for individual buildings and districts are examined using techno-economic analyses. The focus here is on the assessment of heat pumps in district heating systems.

Performance evaluation of real heat pumps in Positive Energy Districts and accompanying simulations: Refrigerant cycle simulations are carried out for the technical evaluation of large heat pumps in districts. The results are verified by real operating data (monitoring results).

Dissemination: The knowledge gained in international and national cooperation will be disseminated through conference contributions, publications in international scientific journals and through the organization of and participation in national workshops.



Austria, Germany, Japan, Switzerland (Operating Agent), the USA

Contact Address

Fabian Ochs
University of Innsbruck
Institute for Construction and Material Science
Unit Energy Efficient Building
Technikerstraße 13, 5. Stock, A-6020 Innsbruck

Christoph Reichl
Giefinggasse 2, 1210 Vienna, Austria

Gerald Zotter
Feldgasse 19, 8200 Gleisdorf, Austria