Designing a more efficient heat network

Efficent sustainable heating.

Following the feasibility studies and the identification of the most suitable properties we will then enter the design phase for the project. This will involve creating detailed plans for individual homes and how to create an efficient heat network and how many boreholes will be needed, the depth of the boreholes and where these holes will be located.

 

Internal heating design

To develop the most efficient heating for each home our team will need to consider the size of the building and the existing fabric of the building. Things considered at this stage will include existing insulation within the building i.e. Does the building have double glazing and cavity wall insulation? This information will be used to size the heat pumps and radiators needed to provide optimum heat levels to the room.

An accurate heat loss calculation for the building is absolutely essential when designing any ground array for a ground source heat pump system.

 

Borehole depth

Boreholes are our preferred ground array for clusters of properties connected via a shared ground loop array heat network, which is common in social housing or new-build development schemes.

Typically, one borehole is required per property. However, in shared ground loop array schemes, one deeper borehole could serve two properties.

 

Borehole location

A geological survey will provide an indication of the type of material that the borehole is going to be drilled into. This material can determine the design of the borehole field.

Different geological conditions have different heat transfer characteristics. For example, a borehole in loose stones has an energy extraction rate of approximately 20 watt per metre (W/m), while granite has an extraction rate of 55 to 70W/m.

A geological survey should also indicate whether there are any mine workings or aquifers present.

The Heat the Streets project and the shared ground loop array will be using multiple boreholes, the boreholes should be spaced at 5 to 6m between centres to avoid any interference between each ground collector. This ensures the ground can recover its heat and stops the ground from freezing.