Scope & Main Activities

Objectives of the Task

The main goal of the proposed international work is to investigate new or advanced solutions for storing heat in systems providing heating or cooling for solar and low energy buildings.

The first objective of this Task is to contribute to the development of advanced storage solutions in thermal solar systems for buildings that lead to high solar fraction up to 100% in a typical 45N latitude climate.

A second objective is to propose advanced storage solutions for other heating or cooling technologies than solar, for example systems based on current compression and absorption heat pumps or new heat pumps based on the storage material itself.

The ambition of the Task is not to develop new storage systems independent of a system application. The focus is on the integration of advanced storage concepts in a thermal system for low energy housing. This provides both a framework and a goal to develop new technologies.

Scope of the Task

Applications that are included in the scope of this proposal include:

• solar houses
• new buildings designed for low energy consumption
• buildings retrofitted for low energy consumption

Focus

The primary focus will be on detached houses with storage units sized to achieve a significant solar fraction.

Systems that are outside the scope, albeit findings could be applied by extension to those systems are:

• large central plants (more than 1 MW) producing thermal energy from a solar collectors field
• administrative buildings with high cooling loads
• large residential buildings with high heating demand (above 200 kWh/m2)
• industrial facilities
• commercial buildings

Other appropriate applications may be considered within the Task if they fit within the main global objective of developing advanced solutions for storing thermal solar energy.

This international effort will be comprised of comparing designs, analysing laboratory results, building pilot installations and evaluating the outcome.

The Task:

• Reviews possible options for storing solar heat considering the “single-family solar house”
• Analyses the best options based on multi-criteria analysis, considering costs, availability, and toxicity of the storage material
• Sets up testing new generation prototypes of solar storage systems to identify a feasible solution, in collaboration with potentially interested industry partners
• Studies and optimises the integration of a combi-system for low energy houses with a 100% solar contribution as the ideal target
• Builds and monitor prototypes of combi-system with advanced storage concepts
• Compares results and issue recommendation and/or patents
• Exchanges the prototype findings and knowledge with industry, solar, thermal or chemical

Evaluation of system concepts

Within this Task, research and industry participants will be organised in teams and given the same boundary conditions (climate primarily) and the same space heating or cooling as well as domestic water demands. They will be asked to design a system meeting these demands under these given conditions and achieving a defined minimum solar fraction with a prescribed maximal storage volume.

A team might be organised within a participating country or across boundaries. Industry partners will be asked to participate in a team.

The different storage technologies that area addressed within the Task include:

• Chemical reactions
• Sorption behaviour (PCM)
• Sensible heat (water stores)

These technologies are at different stages of development.

In order to respect this reality but keep it open for teams to co-operate or compete with concepts based on diverse principles or materials, the final results from each team will not necessarily be at the same level of development.

It is accepted that the delivery of a team can be either:

• a system design evaluated by simulation, (i.e. for a new chemical storage)
• a system prototype evaluated in a laboratory, (i.e. using a PCM or sorption material)
• a tested installed system, (i.e. an advanced water storage based system)

The final report of the Task (december 2006) will analyse and compare the alternatives.

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International Energy Agency Solar Heating and Cooling Programme