@article{ben2026balancing,
title={Decarbonising office buildings: balancing building fabric insulation and geothermal energy for optimal efficiency},
author={Ben, Hui and Kreitmair, Monika J. and Makasis, Nikolas and Kolo, Isa and Brown, Christopher S.},
url={https://www.sciencedirect.com/science/article/pii/S0378778826013058},
urldate={2026-09-15},
DOI={10.1016/j.enbuild.2026.118245},
journal={Energy and Buildings},
ISSN={0378-7788},
publisher={Elsevier BV},
year={2026},
month={09},
day={15},
article-number={118245},
abstract={The decarbonisation of office buildings requires a careful balance between reducing energy demand through fabric efficiency and integrating renewable heating and cooling technologies. This study investigates the combined influence of building fabric insulation and closed-loop geothermal energy systems using the University of Cambridge Civil Engineering Building as a case study. A calibrated building energy model was coupled with subsurface simulations to evaluate energy performance, system viability, and economic implications under three levels of building fabric insulation scenarios (BFI--BFIII). Results show that improved insulation significantly reduces heating demand (from 785 to 271 GWh for lowest and highest levels of insulation), enabling geothermal systems to operate more efficiently and within design constraints, while poorly insulated buildings impose unsustainable loads that require auxiliary systems.  Shallow borehole heat exchanger (BHE) arrays provided reliable performance for moderately insulated buildings but were limited under high loads, whereas 1 km deep borehole heat exchangers (DBHEs) offered higher stability and efficiency with minimal surface footprint. For instance, in the base case scenario the lowest fluid temperature encountered in the shallow array was 0.6 {\degree}C, whilst for the DBHE it was 6.1 {\degree}C. Economic analysis indicated that moderate fabric upgrades (BFII) combined with geothermal systems deliver the most favourable balance of cost, operational savings, and carbon reduction, with diminishing returns observed for deep retrofits (BFIII) when embodied emissions are considered. Over a 50-year period, the combination of building fabric improvements and geothermal technologies can reduce carbon emissions associated to operational conditions by up to 9.5 kt CO2e. The findings highlight the necessity of a fabric-first approach, integrated with appropriately scaled renewable solutions, in this case closed-loop geothermal systems, to provide a robust and cost-effective pathway for office building decarbonisation.},
annote={[**UF]},
}