This report is a case study about geothermal energy system and its application forthe hospital in the city of Gävle. Today the hospital uses district heating and -coolingas their main energy source.There is a report about the hospital in the city of Umeå where geothermal energyhas been installed. Both hospitals have the same need when it comes to using heatand cooling all year round. The hospital in Umeå installed geothermal energy sothat they got a less vulnerable energy system. The emissions of CO2 were also lowereddue to this installation.This report aims to answer the following research question.How geothermal energy can be a option of choice for the hospital I the city ofGävle?The report presents a literature study on subject close to this research question. Focusfor the report is to find out if increased electricity consumption is better than usinglocal district heating- and cooling. The report from the geothermal installation inUmeå has on big difference and that is from which fuels the district heating is produced.In Gävle the energy comes from biomass which gives that the emission factoris almost zero.The calculations and modelling are performed in Excel and the results presented ingraphs.The results are positive both from an economical view and environmental perspective.If the total electricity price doesn’t increase more than 36% per year then geothermalenergy is more cost effective. Looking at the emissions of CO2 equivalentswith an emission factor of 90.4 kg per MWh electricity the COP-factor should notbe lower than 7.5. If that can be reached, then geothermal energy performs betterthan district heating- and cooling.

Geo-energy piles and walls have long been recognized as a promising way to reduce carbon dioxide emissions while providing renewable energy. However, enhancing the thermal performance of these structures has remained a signif-icant challenge. This thesis evaluated five different approaches to improving the thermal performance of geo-energy piles and walls, through a series of experiments using a fully instrumented testing rig. The first approach involved adding graphTHERM powder to concrete to double its thermal conductivity, boosting heat transfer efficiency by an impressive 50% to 66%. The second approach tested slag-based geopolymer concrete as a sustainable construc-tion material for geo-energy piles and walls, reducing CO2 emissions by 44.5% while improving thermal performance by 14% to 21%. The third approach in-volved testing thermally enhanced soils at the geo-energy structures/soil inter-face, resulting in an 81% improvement in heat transfer efficiency. The fourth approach utilized innovative phase change material (PCM) heat exchangers that increased heat transfer efficiency by 75% and 43% in heating and cooling operations, respectively. Finally, incorporated PCM-impregnated light weight aggregates at the interface of the structure soil, significantly increasing tem-perature difference and reducing thermal deformation of geo-energy struc-tures.Overall, these innovative approaches made a significant contribution to enhancing the thermal performance of geo-energy piles and walls. However, approaches four and five, which involve utilizing PCM heat exchangers and PCM-impregnated LWA's, respectively, showed extra benefits in dropping the thermal effect on soils and reducing the thermal damage on those structures. These techniques offer great promise for improving the thermal performance of geo-energy structures.