The comprehensive retrofit of residential buildings has significant potential to reduce carbon emissions and provide additional heath and economic benefits. However, in countries such as the UK, much of this potential is yet to be realised. This paper shows how the concept of 'business models' (BMs) can be a powerful tool for understanding the challenge of improving energy performance and reducing carbon emissions in residential buildings. Through a review of contemporary literature and 18 semi-structured interviews, the paper describes and compares five distinct BM archetypes: the atomised market model, market intermediation model, one-stop-shop, energy services agreement and managed energy services agreement. These models range from the traditional approach to highly innovative energy service contracts. The paper further illustrates how the UK and EU market for retrofitting residential buildings is beginning to trial the more innovative BMs. These emerging BMs are characterised by increasingly industrialised processes and integrated supply chains, a holistic customer offering and single point of sale, longterm energy-saving performance contracts (ESPC) and integral project finance. It is argued that whilst the traditional BM is suitable for the implementation of single or piecemeal energy-saving measures, BM innovation will be required to meet the UK's ambitious climate change targets. Keywords Energy efficiency. Retrofit. Housing. Business models. ESCO. ESPC. Value proposition. Supply chain. Customer interface. Financial model. Governance 1 SAP quantifies a dwelling's performance in terms of energy use per unit floor area, a fuel-cost-based energy efficiency rating (the SAP Rating) and emissions of CO2 (the Environmental Impact Rating) (GOV.UK 2017).