Final report Task 2

IEA HPP Annex 40 Bundesamt für Energie BFE IEA Heat Pump Centre iea International Energy Agency‌

Final Report IEA HPT Annex 40 Task 2

Summary IEA HPT Annex 40 Task 2

In Task 2 of the IEA HPT Annex 40, case studies in order to compare system solutions in nZEB have been performed for different boundary conditions both for central European and Nordic climate conditions, as well as in Japan for climate with pronounced air-conditioning needs.
As building types, both residential buildings and office buildings have been considered.
Thereby, the boundary conditions regarding the nZEB definition and economic boundary conditions have been based on the current national state of definition and markets. Despite the partly different boundary conditions the case studies yield the results, that both in central European as in Nordic countries heat pumps are a favourable candidate for the application in nearly Zero Energy Buildings both in terms of energy-efficiency and cost.
With the heat pump solutions, requirements of nZEB can be reached. Even though heat pumps have higher partly investment cost compared to other heating systems on the national markets of the single countries, heat pumps range among the systems with the lowest life-cycle cost.

Despite the differences in the nZEB balance definition, climate and the economic boundary conditions, the resulting ranking of the different system solutions is quite similar and heat pumps are among the most energy-efficient and cost-effective system solutions, showing a certain robustness of the results, both regarding the energy performance evaluation and the economic boundary conditions.
For the energy evaluation heat pump solutions benefit from the high energy performance in nearly zero energy buildings, since the good building envelopes enable low supply temperatures. Thereby, the nZEB balance can be reached more cost effective, since less on-site generation is required for the compensation of the energy demand of the building. On the other hand, heat pumps may have higher investment cost on the national markets, but regarding the life-cycle cost, this initial disadvantage is compensated by less investment in generation technologies, e.g. PV-systems can be designed smaller, and the higher energy performance of heat pumps reduces the operation cost, which is seen in the life-cycle consideration.
According to these results heat pumps are very suitable for the application in future nZEB also for Nordic climate conditions.

Moreover, the development of two design tools has begun in Task 2 of the Annex.
One of the tools developed at the University of Maryland is dedicated to provide low supply temperature for the heat pump in space heating as well as high temperatures in space cooling without taking a risk of violating thermal comfort in the room zone. Based on model reduction technique of CFD simulation,
the tool can evaluate the indoor thermal environment of rooms in high spatial resolution. Typical comfort parameters like PMV and PPD can thereby be evaluated with less computational expense. Even though radiative systems used to be in focus, the tool can also be applied for convective systems like induction units of ducted air-handling units or ductless room air conditioners. For these systems case studies are contributed.

The other tool developed at SINTEF Energy Research in Trondheim deals with an optimised design of the heat pump system for the objective function of CO2-eq-emissions and cost. Based on preprocessing of the building data, an iterative optimisation of the system solutions regarding a cost-effective zero emission system design can be performed. Since the different models have recently be gathered in Matlab Simulink, a future development perspective is the automatic optimisation of the system with included optimisation algorithms. Summarising, both tools can help to create even more energy-efficient and cost-effective system designs for the application of heat pumps in nZEB.  


IEA HPT Annex 40
Final Report Task 2