Presentation of GEOFIT at the European Shallow Geothermal Days 2022
Title: Introducing GEOFIT: Easy-to-install, economical and enhanced geothermal systems for energy efficient building retrofitting
Author: Henk Witte (Groenholland)
Summary: GEOFIT is an EU-funded research project focussing on the use of shallow geothermal energy for heating and cooling of buildings. It specifically addresses retrofitting, therefore tackling the specific issues one has to face while designing, installing and operating a geothermal system in an existing building (Ground source Heat Exchanger – HEX, Heat Pump – HP, heating and cooling emission system).
GEOFIT aims to answer to the challenge by developing easy-to-install and efficient underground coupling systems, including historical buildings, to make geothermal energy a standard source of heat and cold in building renovation. Such systems consider the difficulties in drilling in built environments. The project also develops improved, more cost-efficient and less environmental-impacting heat pumps to optimize the use of the energy generated by geothermal systems. GEOFIT embraces the whole path of design-site survey-installation-operation. It particularly investigates coupling between GHEX and HP and between HP and heating/cooling emission systems, thus providing guidelines for planners to reduce errors and ensure high performance of the systems.
To aid the selection of different Ground Heat Exchanger technologies and support the design, an advanced integrated design toolkit is developed. This engineering toolkit allows the engineer to design and compare the different GHEX (vertical, horizontal, slinky and spiral/earth basket type) in an integrated model framework. The approach in the engineering toolkit is based on the well-known finite line source approach and implements G-functions to speed calculation. New finite line source models have been developed and validated for spiral type heat exchangers. Other advances include detailed (temperature dependent) fluid properties correlations and inclusion of seasonally varying temperature gradients. The finite line source model for spiral heat exchangers has been validated with sand-box experiments and CFD calculations.