It can be cheaper in capital cost to install one integrated Ground Source Heating and Cooling system than two separate systems. The traditional alternative is to provide heating in winter with a gas boiler (burning fossil fuels) and a second separate system to provide cooling in summer (whose high use of electricity causes further burning of fossil fuels at the power stations).
The ground source method of providing space cooling is radically less expensive to run than providing cooling by using roof mounted chillers because it is much cheaper to heat exchange with cold ground than hot air.
There is a by-product of heat exchanging with cold ground to provide cooling to the building in summer: this warms up the ground in time to provide heating more cheaply in winter.
There is also a by-product of heat exchanging with warm ground to provide heating to the building in winter: this cools down the ground in time to provide cooling more cheaply in the summer.
This virtuous circle can be repeated year after year to provide a sustainable heating system. What’s more you will only face an annual maintenance cost for one system instead of two.
The ground – mother earth – can act as a very large store of heat energy: it can provide Thermal Energy Storage. It can be used as a heat source in winter, or a heat sink in summer. The ground can be used to moderate the temperature in buildings standing on it.
District Heating & Cooling Networks
The government is promoting district heating systems with its massive Heat Networks Investment Programme. The idea is to reduce carbon emissions from heating as the use of Combined Heat and Power (“CHP”) engines in district heating makes fuller use of the inherent energy in gas if gas is used to generate electricity and the heat from generation is circulated as heat instead of being wasted to the atmosphere. However, the heat generated is also likely to be wasted in summer and so CHP district heating does not always produce the benefits assigned to it. CHP is also based on combustion which not only emits CO2, it also emits NOx, SOx and particulates which are a serious risk to health in urban environments.
In practice the use of CHP for district heating has been overtaken by events. The successful programme to decarbonise the grid means that the optimum route for
decarbonising heating has moved from using CHP engines in district heating networks towards using much lower distribution temperatures in district heating systems – eliminating heat losses to the ground – and using ground source heat pumps in each building to extract heat from the communal ground array whenever a building needs heating.
With improvements in the build construction of modern buildings, many commercial buildings need cooling in summer. A CHP district heating system is not able to provide cooling unless a second set of separate insulated pipes are installed to distribute cold water for cooling. This is seriously expensive. There is a much more natural alternative: where ground source heat pumps have been installed for heating using an ambient ground temperature network, the same heat pumps can be engaged in reverse to reject heat to the communal network and provide cooling.
Installation of Ground Source Heating and Cooling Systems
To get the full benefit of a GSHC installation you will need to employ someone with design and installation experience of integrated heating and cooling systems. A GSHC system may not perform well unless it is incorporated into a good design by someone who understands the needs of the building, the use to which the building is being put and the local geology.
For more information on installation of ground source heating and cooling from an experienced source please contact one of our members.
The Environment Agency encourages well-balanced Ground Source Heating and Cooling systems. See Environment Agency position on GSHC.