How to reduce the cost of GSHP systems?

Geothermal heat pumps, also known as ground-source heat pumps (GSHP), can help significantly reduce energy consumption for heating and cooling a building, while limiting the power required from the electrical grid. However, geothermal systems require a heat pump and a ground heat exchanger, which can represent a significant cost premium over a conventional HVAC system, discouraging their use in institutional, commercial or industrial buildings.

This is particularly true when the ground heat exchanger (GHE) is sized with rules of thumb or, unrealistic or overly conservative design assumptions. The resulting geothermal system is then oversized, which can lead to excessive construction costs.

There are several complementary approaches to design a ground loop that is both thermally efficient and less expensive. Some of the most appropriate measures for large-scale projects include:

• Precise assessment of the building's thermal loads
• The design of an HVAC system, such as a hybrid system, leading to balanced ground loads
• Use of ground thermal properties deduced from a thermal response test
• Designing geothermal wells with low effective resistance
• The design of a geothermal field (number, position and depth of wells) to maintain fluid temperature within the operating range of the heat pumps.

However, it is possible to easily integrate these design measures using GHE Analysis software, and instantly simulate a heat pump's inlet temperature, calculate its coefficient of performance at full or partial load, and evaluate its energy consumption and electrical power demand. The use of GHE Analysis thus helps to reduce the construction costs of systems using geothermal heat pumps.