Germany was the first country to join the IEA HPT already in April 2022. Now, another institution has joined the German team in March 2024, the Institute of Solar energy research Hameln ISFH. The ISFH has an ongoing project called “WQeff”, which deals with efficient and renewable operations of heat pump in districts. The project comprises 4 districts with both air- and ground-source heat pumps installed in individual buildings as welle as connected by grids. Both monitoring results and simulation work of these so-called “Heat pumps districts” will be contributed to the Annex 61 work. The Annex 61 welcome the new member of the German Annex 61 team.