Deep retrofitting: carbon vs cost payback

Perisoglou, Emmanouil ORCID: https://orcid.org/0000-0002-7295-6058, Patterson, Joanne ORCID: https://orcid.org/0000-0002-4440-159X, Li, Kaiwen ORCID: https://orcid.org/0000-0002-3708-029X and Hou, Shan ORCID: https://orcid.org/0000-0002-8794-1510 2025. Deep retrofitting: carbon vs cost payback. Presented at: CIBSE IBPSA-England Technical Symposium 2025, London, UK, 24-25 April 2025. CIBSE,

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Abstract

This paper provides a methodology for calculating carbon and cost payback for deep retrofits with known capital cost and embodied carbon. Cost payback was calculated by subtracting operational cost savings from the capital cost whereas carbon payback was calculated by subtracting operational carbon savings from the embodied carbon. Two future energy cost scenarios combining national UK and global projections were used for the cost payback predictions. Three future grid carbon intensity scenarios based on the UK 2030 clean power target were utilised to calculate carbon payback. The methodology was applied to a social housing case study that underwent a deep low carbon retrofit. The homes were monitored and modelled before and after the works. Projected data illustrate that carbon payback is 5.9 to 7.9 times faster than cost payback. Embodied carbon associated with imported PV panels is the most dominant carbon contributor to the system and boiler fossil fuel avoidance is the most significant cost and carbon saving.

Item Type:	Conference or Workshop Item (Paper)
Status:	In Press
Schools:	Schools > Architecture
Subjects:	N Fine Arts > NA Architecture T Technology > TA Engineering (General). Civil engineering (General)
Publisher:	CIBSE
Funders:	Low Carbon Built Environment
Related URLs:	Publisher
Date of First Compliant Deposit:	6 November 2025
Date of Acceptance:	25 April 2025
Last Modified:	06 Nov 2025 15:55
URI:	https://orca.cardiff.ac.uk/id/eprint/182189

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