Thermal Conductivity Test and Analysis

A thermal conductivity test includes the drilling of a single borehole, as associated pipe and grouting to facilitate the acquisition of data from the rock formation beneath the site in which you wish to install a vertical ground heat-exchanger. The gathered data will provide information regarding the thermal conductivity, thermal diffusivity, and undisturbed temperature of the earth at a depth of 100 meters from the earth’s surface. Thermal conductivity/diffusivity of the ground is essentially the ability of the ground to absorb and/or release energy. This information is necessary in order to accurately design a ground heat-exchanger capable of transferring energy to and from the earth for the purpose of heating and cooling a building.

A Thermal Conductivity Test includes:
  • Transport of all necessary drilling, grouting, and testing equipment to the site.
  • Drilling of a single borehole of 6” diameter to a depth of 100 meters from the earth’s surface at a suitable location.
  • Installation of a 1” high density polyethylene plastic pipe and u-tube assembly manufactured to standard SDR11, fusion welded at all joints, pressure tested, and charged with potable water.
  • Provide a permanent environmental seal of the entire borehole using a limestone based grout, sand, and water mixture. The grout mixture shall be pumped from the bottom of the borehole upward to the very top.
  • A detailed thermal conductivity testing report.
General Thermal Conductivity Drilling and Testing Procedure:
The table below describes the procedure for a thermal conductivity test and analysis:
Steps Timeline
1. Equipment Transportation and Set-up 1 day
2. Drilling, Piping, and Grouting of 100 meter borehole 3 days
3. Undisturbed Earth Temperature

In order measure the undisturbed temperature of the earth, the finished geothermal borehole must remain in the earth until it assumes the same temperature as the earth
5 days
4. Conductivity Test* 48 hours (continuous)
5. Conductivity Analysis 2 weeks

* If the conductivity test is interrupted during the 48 hour test, the geothermal borehole must be allowed to return to the steady-state conditions of the earth before the test is attempted again.
Conductivity Testing