Technologies for the design and production of natural gas absorption heat pumps for residential use

The i-GAP project, aimed at achieving a low-carbon zone, intends to develop technologies for the design and production of natural gas absorption heat pumps for residential use, featuring an innovative thermodynamic cycle, compact dimensions and suitability for high volume production. The solutions can also be integrated easily into the plants and systems of a building and can provide a quantification of the energy, environmental and infrastructural benefits resulting from the adoption of this heating technology.


The building sector is responsible for about 40% of energy consumption and 36% of climate-altering emissions. The majority of energy saving opportunities are concentrated in the upgrading of pre-1990 residential buildings. These homes (about 90% of residential buildings) represent the most energy-intensive part of the building stock, (EPH >200 kWh/m2a), have a surface area of between 60 and 200 sq. m and are mostly heated with gas boilers (PEAR Lombardy 2015) connected to radiators (distribution system). Improvements to the building envelope, together with the implementation of some new plant engineering technologies (e.g. solar thermal, heat pumps) make it possible to reduce energy consumption.


Within this context, the natural gas absorption heat pump (GAHP) immediately emerged as the most suitable technology thanks to its distinguishing features and the resulting benefits:

  • high primary energy conversion efficiency
  • high thermal gradients between the renewable source and the point of use, which enable easy use of the aerothermal source and the use of radiators in energy upgrading projects
  • reduced size (or surface area) of the heat exchanger on the environment side, which guarantees easy installation and reduces the costs of the component itself
  • low emissions of climate-altering gases (also thanks to the use of refrigerants with zero GWP), CO, OGC, NOx and PM (thanks to modern gas combustion technology)
  • reduced noise, thanks to the compact size of the fan and the almost total elimination of moving parts
  • use of the existing energy infrastructure, for both the transmission network and the natural gas distribution network

In December 2017, the Lombardy Region decided to include the i-GAP project in the research and technological development funding that is part of the Regional Operational Programme 2014-2020, co-financed by the ERDF - European Regional Development Fund 2014-2020. ATIT has assumed the role of project leader, supported by partners including Politecnico di Milano and SNAM.