Sustainability Journal

November 2012 Issue (files are in PDF format)

Linking large and small buildings to minimize costs and eliminate GHG emissions

In situations where one or more large buildings are located close to blocks of residences the City Block concept can be applied to reduce the construction costs compared to conventionally heated buildings, to completely eliminate GHG emissions from the heating/cooling/DHW systems, and to greatly reduce the operating costs. Large buildings presently waste enough heat to heat all of the homes in Canada. Seasonal storage makes it possible to store that heat so that it can be used by the neighbouring homes. The heat store is located on the grounds of the large building, on which the solar thermal collectors for DHW (also using seasonal storage) are also mounted. The homes are heated and cooled by heat pumps that are linked to the shared central heat store, which also provides the heat for the domestic hot water (DHW) for the homes. There is no need for furnaces in the homes and most of their energy needs are met by the local energy from the large building. The concentric heat store is very compact and needs an order of magnitude less drill hole length compared to GSHP systems so its cost is very modest.

The large building in this hypothetical project has a floor area of 200,000 square feet and there are 60 homes for which average heating/cooling/DHW loads have been assumed. The results will be posted as soon as the calculations have been completed.

This is the first of three outlines that will show how communities can share central heat stores. In this case the primary source of energy is the (normally wasted) heat from the big building. In the second example the principal source of energy is the hot summer air that is used to heat a block of residences. In the third outline an existing system (Toronto's Enwave system) is described, showing how the cold winter air is being used to cool large buildings. All of these systems can also collect, store and deliver high temperature heat for heating hot water, greatly reducing the need for using electricity or natural gas for that purpose. This ability to use unconventional energy sources and to more effectively use natural sources like the sun demonstrate how our cities could be transformed in their energy use while saving money at the same time.