Theme III

Mid-to Long-Term Thermal Storage for Buildings and Communities

Theme Leaders

  • M. Bernier
  • M. Rosen


This Theme will deal  with the storage of excess thermal renewable energy when it is not immediately required. The thermal  storage may be a building-integrated mass, a central active storage system such as tanks of water, or an earth storage working through buried pipes, the last for both medium-term and seasonal storage. It may also incorporate phase-change materials. This Theme will have a major component-link to Theme. It will also consider district heating/cooling.


To enhance designs of smart NZEBs and the likelihood for their implementation, an improved understanding and modeling is needed of thermal storage systems. This includes better modeling of thermal storage systems themselves, so as to predict performance and operating characteristics with improved accuracy, as well as enhanced modeling of the integration of thermal storage into buildings, their component parts and related energy systems. The integration often involves buildings utilizing heat pumps (ground-, water- and air-source) as well as district heating and cooling systems. Short-duration (diurnal) thermal energy storage is appropriate for some applications, while longer term storage (based on seasonal cycles) is optimal for others. Sometimes, a combination of short-, medium- and long-term storage is required to yield the most benefits from building and community energy systems, as is the case at the Drake Landing Solar Community in Okotoks, Alberta. Ground-based thermal storages  are proving increasingly advantageous, and for these there is a significant need to develop advanced methods for predicting ground heat transfer, especially for new in-ground applications such as earthtubes, two-phase flow boreholes, and grouts that experience a change of phase. The appropriate integration of thermal storage into buildings and communities where renewable energy sources (e.g., solar) and advanced technologies are also utilized is particularly complex. As such, improved models of thermal storage will be developed and (in conjunction with Themes 1 and 4) the system performance will be studied to achieve optimal configurations and operation strategies.