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Thermal & Electrical Energy Storage in Ultra-Low Energy Buildings

  • Annex 15
  • Completed
  • Energy storage in energy systems


Sustainable buildings will need to be energy efficient well beyond current levels of energy use. They will need to take advantage of renewable and waste energy to approach ultra-low energy buildings. A goal of achieving such buildings by 2030 has become a common international goal. Such buildings would reduce current building design energy consumption by 60 to 90% with the remainder to be provided by renewable thermal and electric generation.

Such buildings will need to apply thermal and electrical energy storage techniques customized for smaller loads, more distributed electrical sources and community-based thermal sources. Lower exergy heating and cooling sources will be more common. This will require that energy storage be intimately integrated into sustainable building design. Many past applications simply responded to conventional heating and cooling loads. Recent results from low energy demonstrations, distributed generation trials and results from other Annexes and IAs such as Annex 37 of the ECBCS IA, Low Exergy Systems for Heating and Cooling need to be applied.

Although the ECES IA has treated energy storage in the earth, in groundwater, with and without heat pumps and storing waste and naturally occurring energy sources, it remains to integrate these into ultra-low energy buildings capable of being replicated generally in a variety of climates and technical capabilities. Electrical energy storage has recently made technical advances that are transforming renewable electrical generation into dispatchable electricity and reliable backup.

Energy storage has often been applied in standard buildings that happened to be available. The objective was to demonstrate that the energy storage techniques could be successfully applied rather than to optimize the building performance. Indeed the design of the building and the design of the energy storage were often not coordinated and energy storage simply supplied the building demand whatever it might be.

Activities included:

  • Coordinated national reviews of energy storage use in energy efficient buildings.
  • Collaborative evaluation of energy storage usage and proposed efficient systems based on the national reviews, other Annex results and a common evaluation model.
  • Development of Sustainable Energy Storage Designs for a variety of ultra-low energy buildings using thermal, phase change materials and electrical storage options. Energy storage designs for the following building types would be examined:
    • A distributed electrical generation multi-unit residential building that stores cogenerated heat energy for multiple uses.
    • A renewable energy single family house
    • A small community that shares energy among various types of buildings and occupancies including residential, commercial and institutional.
  • Apply, monitor and evaluate demonstrations of these Designs in a number of countries and climates.

The general objective of the Annex is to ensure that energy storage techniques are properly applied in ultra-low energy buildings and communities. Applications of these designs are foreseen in a post-Kyoto world where total CO2 reduction is required. Proper application of energy storage is expected to increase the likelihood of sustainable building technologies.

Specific objectives include:

  • assess the potential of harnessing natural energy sources to supply building heating and cooling through energy storage;
  • assess the use of energy storage (electrical and thermal) to optimise the efficiency of distributed generation;
  • develop and evaluate energy storage conceptual designs suitable for specific applications.

Energy storage techniques need to respond to the needs of future (2030) buildings with very low energy and power requirements. This would include the use of natural energy from earth and water, waste energy from sources such as distributed generation and conventional storage technologies sized and modified to operate efficiently at customised temperatures and quantities.

Task agent(s)

No operating agent(s) listed


Annex 15 is completed. For requests and information, please contact the ECES TCP secretariat using the contactform below.