A SUSTAINABLE REBUILT CITY USING GEOTHERMAL HEAT PUMPS: THE CHRISTCHURCH STORY

Abstract

The post-earthquake re-build of Christchurch’s inner city has allowed large commercial-scale building owners to design and utilise more efficient building energy systems using aquifer based geothermal heat pump (GHP) technology. The city is located on a series of confined aquifers, ranging in depths from 5 m to greater than 200 m. These aquifers contain water that is consistently between 12-13oC providing a stable consistent source of heat energy. The systems extract heat from this source and also use it as a sink for cooling. The overall annual energy requirements from a large commercial building will usually require a greater cooling load than heating load. Six years after the earthquakes, there are over fifteen large GHP projects under-development or completed across the city and this paper summarises these GHP developments with a view to showcasing the present use of this technology in New Zealand.