IEA HPT Annex 49: Design and integration of heat pumps for nZEB

A dominating concept to reach a nearly Zero Energy Building (nZEB) is the combination of solar PV systems and heat pumps. The extended scope of the Annex 49 regards the balance of single buildings and groups of buildings/neighbourhoods, a thorough investigation of heat pump integration options for nZEBs and nZE neighbourhoods by means of monitoring and simulation as well as the design and control optimization for heat pumps in nZEB and the integration into energy systems.

Short Description

Political strategies in the frame of climate protection in the building sector indicate that nearly Zero Energy Buildings are the next step of energy efficient buildings. The criterion, currently agreed on, is the nearly zero energy balance on an annual basis.

Based on case studies carried out in the previous Annex 40 with different technologies, the scope in this Annex is extended from the balance of single buildings to groups of buildings, an issue still in discussion for the nearly zero energy balance. Groups of buildings open up opportunities for load balancing between different use patterns and energy needs and compensation of energy consumption of older buildings by the surplus of highly efficient new buildings with a plus balance. Furthermore, integration options, e.g. for collective storage or source integration exist as common ground storage/source. Moreover, development of design tools has begun in Annex 40 and shall be completed and extended, also taking into account the energy flexibility a system solution can offer as design criteria besides performance and cost. The main sector targeted with the Annex is heat pump manufacturers, engineering offices and building companies committed to the technical concept and design of equipment of high performance buildings. Moreover, evaluations of real performance of heat pumps shall be transformed into recommendation for designers, industry or policy makers to support the process of nZEB introduction and establish the heat pump as standard equipment for nZEB.

The objectives of this Annex are to:

  • Evaluate and compare definitions of nZEB across the participating countries regarding the impact on building technologies with heat pumps
  • Evaluate the design of heat pump systems for different applications in residential or office buildings regarding performance, cost, load match and demand response.
  • Refine integration options for building technology with heat pumps in terms of multi-functional operation and needs of integrated system (e.g. source regeneration, supply reheating, back-up cooling, temperature related heat decoupling, etc.)
  • Gather experience of monitoring of buildings across different participating countries regarding concepts and technology under different climate and market conditions
  • Derive recommendations for integrated heat pump systems as well as heat pump design and control in single nZEB and groups of buildings.

The Annex is work is divided into 5 Subtasks:

  • Task 1. State-of-the-art of definitions and nZEB concepts for single buildings and groups of buildings
  • Task 2. System integration options of heat pumps for single buildings and groups of buildings
  • Task 3. Technology evaluation and development/Continued field evaluation for nZEB
  • Task 4. Design and control of nZEB technologies
  • Task 5. Dissemination of results

Project Images

Terms of use: The pictures listed underneath the header “Project Pictures” originate from the projects in the frame of the programmes City of Tomorrow, Building of Tomorrow and the IEA Research Cooperation. They may be used credited for non-commercial purposes under the Creative Commons License Attribution-NonCommercial (CC BY-NC).


Belgium, Deutschland, Finland/Estonia (Interest), Great Britain (Interest), Japan (Interest), Canada (Interest), Norway, Sweden, Switzerland, USA

Contact Address

Universität Innsbruck
Fabian Ochs
Technikerstr. 13, 6020 Innsbruck
Tel. ++43 512 507 63603

IWT, TU Graz
Andreas Heinz

AIT, Wien
Philip Horn