GeoT*SOL Frequently Asked Questions

Yes, if we assume that the following clauses are met:

4.3.1 Permitted as alternative methodology;

4.2.12 “ Validated for UK use...” due to use of UK climate files;

4.2.12 a) Site average ground temperature is an input and hourly air temperatures form part of the hourly climate data;

4.2.12 b) Site ground thermal conductivity value (in W/mK) is an input and the user can consider the depth of the water table;

4.2.12 c) The annual heating energy consumption for space heating & domestic hot water are input/calculated values;

4.2.12 d) The power extracted from the ground (in kW) is stated;

4.2.12 e) The temperature of the thermal transfer fluid entering the heat pump is stated graphically throughout the year;

4.2.13 The temperature of the thermal transfer fluid entering the heat pump can be designed to be >0oC at all times using a 20-year average climate file since the temperature is specifically shown graphically in the results.

With these assumptions, a GeoT*SOL quote can be used as an "alternative methodology" and should be used in conjunction with the MIS 3005 methodology-based quote.

The basic message is that the MIS methodology has a very limited number of variables that it considers, whereas GeoT*SOL basic is for design and anticipates a wide range of variables. For more details about the SAP methodology and Valentin software see: here.

The "Primary energy savings" & "CO2 emissions avoided" figures listed in the project report are comparing the energy running costs of your designed heat pump system to a natural gas heating system.

The problem of cooling the ground can be resolved by undertaking one or more of the following design actions:

Reduce space heating or DHW heating demand.

Increase total length of borehole heat exchanger (either number or depth of boreholes).

Changing the grouting type from "simple grouting" to "thermally enhanced infill".

Changing the diameter of the borehole.

Increasing the size of electrical element specified.

Altering the "double u pipe" or "single u pipe" parameter.

Altering the capacity of the selected heat pump.

Please note: The effects of changes to the design (on the warning message) will only be taken into account when you run another simulation.

To input this variable, you will need to use the look-up tables provided by the Microgeneration Certification Scheme.

To download the current document, please see here (MIS 3005 - Supplementary Information I - MCS 022 Ground look-up tables)

To find the correct table within the document you would need to calculate the FLEQ run hours. To do this:

FLEQ = Total energy consumption (kWh) / Heat pump capacity (kW).

For more thermal conductivity values, please see Appendix C: Values for thermal conductivity of MIS 3005 - Heat Pump Systems.

Please note the assumptions listed above each table, of which the following can be inputted into GeoT*SOL basic or adjusted accordingly:

Borehole diameter = 130 mm

Construction type = Single U-Pipe

Infill = Thermally enhanced.

In addition, British Geological Society keeps a record of borehole scans on their website, which can be used to find ground conditions for completing this calculation.