This is an international R&D project on the evaluation and demonstration of actual energy efficiency of heat pump systems in buildings. The project is within the framework of the IEA TCP on Energy in Buildings and Communities (EBC).

Certain heat pump systems in buildings have previously been found to exhibit low energy efficiency under low partial load conditions, while other heat pump systems have been able to maintain higher energy efficiency under the similar conditions. Therefore, technical guidance on how to improve the overall energy efficiency of such heat pump systems is critical information for many engineers and HVAC system designers. Further, public policy and decision makers require support on how requirements to follow such technical guidance can be implemented within building energy codes and regulations.

Background

Heat pumping technology is one of the most promising and indispensable technologies to dramatically improve building energy performance toward decarbonised societies, with many industrialised countries already targeting interim goals for 2030 and complete decarbonisation by 2050. However, we have to ask ourselves whether researchers have sufficiently clarified the actual characteristics of such systems found in buildings. To achieve much greater deployment of this technology, it is essential to share data on the actual characteristics of the technology and to publish know-how on how to correctly monitor and utilize the characteristics. In general, heat generators for space heating and cold generators for cooling systems use considerable amount of energy in buildings, when compared with other parts of HVAC systems. In the design process, their capacities are determined taking thermal performance of the building envelope and climatic condition of the building location into consideration. Their sizing is an indispensable and critical practice, and to avoid the risk of insufficient heat (or cold) supply, HVAC system designers have to determine this with enough spare capacity to allow for unpredictable factors such as changes in building use. But this oversizing found in practice is one of the reasons why low partial load situations seem to occur frequently under real conditions. The energy efficiency of a heat generator under low partial loads is particularly important when this system's contribution to higher overall energy efficiency is evaluated. So, heat generators with higher efficiencies under low partial loads become very valuable for HVAC design. This is also the reason why HVAC design techniques such as subdividing the total necessary capacity among multiple heat generators and how these are sequenced can be effective methods to improve systems’ energy efficiency through improved sizing practice and system control.

Heat pumps are regarded as a very promising form of energy-efficient heat generator, especially under electrified and decarbonized energy supply systems. However, publicly available information on the actual characteristics of heat pump systems in buildings is still insufficient to meet the needs of both HVAC system designers and product manufacturing engineers. In fact, there seems to be a huge potential to improve design practices and accuracy of energy calculation methods, which can be applied to strengthen building energy codes and regulations. Especially for heat pump systems, information on actual partial load characteristics and energy efficiency of heat generators under such conditions should be collected and analysed, and the outcomes should then be shared among designers and engineers engaged in heat pump systems for buildings.

This project will contribute to the research themes (objectives) of IEA EBC TCP, which are described in its Strategic Plan 2019-2024, as follows:

“Planning, construction and management process reducing the performance gap”

“Low tech, robust and affordable technology”

This project will also contribute to the research theme (Mean) in the Strategic Plan 2019-2024 as follow:

“Tools for design to operation, including building energy standards and LCA”

Objectives

The overall objective of this Annex is to establish the scientific basis for more accurate estimation of the energy efficiency of heat pump systems for heating and cooling of buildings and for more reliable and transparent design strategies for building applications of heat pump systems. To meet this objective, the following activities will be carried out:

• Literature survey and collect existing field monitoring results on the behaviour of heat pump systems in buildings. The data shall include at least input (energy use) and output (thermal load) of heat pump systems, peripheral conditions such as outdoor temperature, characteristics of the heat generators such as product test results and specification of compressor(s), and characteristics of buildings and overall HVAC systems.
• Development of a manual on monitoring methods for energy efficiency and other characteristics of heat pump systems in buildings, and new data acquisition techniques on which to develop a database.
• Development and validation of alternative methods for predicting energy efficiency and energy use of heat pump systems in buildings under different conditions including partial load ratios, by utilizing product information based on existing test standards and protocols.
• Development of design guidelines for more energy efficient heat pump systems with demonstration data from applications in buildings.

  The overall objective of this Annex is to establish the scientific basis for more accurate estimation of the energy efficiency of heat pump systems for heating and cooling of buildings and for more reliable and transparent design strategies for building applications of heat pump systems. To meet this objective, the following activities will be carried out:

  • Literature survey and collect existing field monitoring results on the behaviour of heat pump systems in buildings. The data shall include at least input (energy use) and output (thermal load) of heat pump systems, peripheral conditions such as outdoor temperature, characteristics of the heat generators such as product test results and specification of compressor(s), and characteristics of buildings and overall HVAC systems.
  • Development of a manual on monitoring methods for energy efficiency and other characteristics of heat pump systems in buildings, and new data acquisition techniques on which to develop a database.
  • Development and validation of alternative methods for predicting energy efficiency and energy use of heat pump systems in buildings under different conditions including partial load ratios, by utilizing product information based on existing test standards and protocols.
  • Development of design guidelines for more energy efficient heat pump systems with demonstration data from applications in buildings.