The final results of IEA HPT Annex 61 have been presented on different conferences in summer and autumn 2026.
After the final workshop on the IEA Heat Pump Conference in Vienna in May 2026, results of the Swiss contribution have been presented on the national Swiss Heat Pump Conference 2026 in June 2026. Results deal with monitoring of an old industrial district which is transformed to a new district for living and working with 1000 flats and 1000 work places in the final stage. The district is supplied with centralised heat pumps. By simulation of the district it was confirmed that by changing the DHW integration, the grid temperature can be lowered and the system performance can be significantly improved.
On the Eurosun 2026 in September, a study on the heating grid topology was presented, which compares different grid types of a high temperature grid, a mid temperature grid with local booster heat pumps and a source temperature as distribution of a favourable source temperature for decentral heat pumps. It is confirmed, that decentral heat pumps have lowest use temperatures with the least losses and auxiliary expenditure. Booster heat pumps can enable lower grid temperatures, but there is investment in both central and decentral heat pumps and the grid, which may affect the economic benefits. High temperature grids can have economic advantages at high heat line density and require the lowest decentral installation of just a transfer station amended eventually by heat storages.
On the Geothermiekongress 2026 in October, the geothermal borehole source was considered. It was confirmed that an increase of the source temperature above the typical design to -1.5 °C after 50 years, the number of required boreholes can increase significantly based on the district loads. Moreover, it has also been evaluated how the grid configuration affects the required heat source design.