LIFE Project Cover Photo

Solar thermal collectors with a ZERO electricity heat pump & energy storage for sustainable heating and cooling

Reference: LIFE11 ENV/SE/000838 | Acronym: SUNCOOL



Buildings account for 40% of total energy consumption and 36% of CO2 emissions in the EU, with heating and cooling technology accounting for approximately half of these figures. The demand for heating and cooling systems continues to grow in the developed countries, as well as in fast-growing economies such as China and India. Therefore, energy saving technology that can be retrofitted at reasonable cost is of particular value. This would improve indoor conditions in residential and commercial buildings. Energy storage avoids overload during peak hours, which should lead to reductions in the running cost for air-conditioning. Additionally, the electricity network need not expand to cope with extreme air-conditioning use during peak hours, resulting in less need for investment in power plants and the electricity distribution network. SunCool is a device that works with an existing boiler or heat pump, thereby reducing the consumption of fossil fuels. The technology can be installed in existing buildings, so it has the potential to be used widely. It combines renewable energy, energy efficiency and the reduction of CO2 emissions. SunCool technology has been developed and validated by ClimateWell since 2008. However, this technology needs to be demonstrated in a pilot installation.


The overall objective of the SUNCOOL project was to demonstrate in a commercial setting the coordinating beneficiary ClimateWell’s patented SunCool solar thermal collectors, with integrated thermal heat pump and energy storage, for sustainable heating and cooling. Specific objectives were to demonstrate the energy effectiveness of the solar collectors in a pilot installation, and to show the conversion of solar energy into heating and cooling with a large as possible solar contribution and a low as possible electricity consumption. The aim was for this system to provide the building with air-conditioning, heating and possibly also hot water. The project intended to show the fully functioning solar collectors to potential customers, partners, stakeholders, target groups and others, and disseminate its finding around Europe.


The SUNCOOL project demonstrated highly-innovative patented solar thermal collectors, incorporating zero-electricity heat pumps and energy storage, for sustainable heating and cooling. This was the first large-scale evaluation of the SunCool system developed by ClimateWell at its headquarters in Stockholm (Sweden). The integrated solar collector system for heating and cooling was installed on a commercial building - a coffee roasting house - in the inner harbour district of Karlstad (Sweden). SunCool solar panels were fitted over a 180 m2 area on the roof and connected to the building’s existing circuits for heating and air conditioning. The project succeeded in achieving its target of reducing energy use by 90% (primary energy consumption, after parasitic losses).

The project demonstrated a range of environmental benefits due to the use of SunCool solar collectors, including its all-in-one capability (heating, cooling and energy storage); high energy savings and CO2 reductions as a result of using twice as much solar energy, due to the energy storage capability of ClimateWell’s SaltX Technology (which stores energy in salt crystals); and the ability to deliver solar heating during the night (ideal in situations where sunny days alternate with cold nights). The project confirmed that the thermal heat-pumps (CoolStore tube) consume zero external electricity. Together with a lack of moving parts and good corrosion protection, this all contributes to the system’s robustness. Much lower energy losses occur than for any other solar heating and cooling solutions.

Prior to switching on the system, the project team modelled the operation of the existing heating and cooling system in the building, together with meteorology data, and this definition of the building’s needs informed the installation design. During operation, the SunCool system was monitoring using a network of devices (e.g. energy meters, temperature sensors and solar irradiation meters). A series of simulations and analysis, (including LCA and LCC) was conducted to understand the applicability and profitability of SunCool in a European building context.

In order to evaluate the economic impact, based on the current data and outcomes from the installation in Karlstad, capital expenditure and profitability were calculated for three types of building (hotels, hospitals and homes) in eight different climatic locations, in Germany, Italy, Spain, Sweden, India, China, USA and Sri Lanka. The minimum payback time for the installation was estimated as 3.1 years, with variations depending on the different energy-mixes in different countries as well as climate characteristics.

The project disseminated its findings via trade fairs, participation at solar energy conferences, scientific publications and articles in specialist magazines, and a website. The findings have generated much interest as the system has a fast and easy installation, thanks to the integration of key components in the collector, and the cost savings give attractive payback times. Consequently, the new technology could provide substantial business opportunities to Europe’s leading manufacturers of solar thermal collectors.

Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).


Reference: LIFE11 ENV/SE/000838
Acronym: SUNCOOL
Start Date: 01/06/2012
End Date: 01/03/2016
Total Eligible Budget: 3,653,371 €
EU Contribution: 1,826,685 €
Project Location:


Coordinating Beneficiary: ClimateWell AB
Legal Status: PCO
Address: Instrumentvgen 20, 126 53, Hgersten, Sverige
Contact Person: Per Olofsson
Email: Send Email

LIFE Project Map



  • Renewable energies
  • Supply


  • energy saving
  • sustainable development
  • heat supply
  • renewable energy


  • Directive 2012/27 - Energy efficiency (25.10.2012)
  • COM(2011)112 - "A Roadmap for moving to a competitive low carbon economy in 2050" (08.03.2011)
  • Directive 2009/28 - Promotion of the use of energy from renewable sources (23.04.2009)


Name Type
ClimateWell AB Coordinator
Lofbergs Lila AB Participant