The paper uses a multinomial logit model to study the determinants of domestic space heating systems in Ireland. Nine types of heating systems are considered, classified by fuel type (liquid, electric, gas and solids or combinations thereof). Heating system choice is modelled as a function of household socio-demographic variables and dwelling attributes; information on occupants' knowledge of fuel costs, energy efficiency, and fuel emissions; as well as actual environmental behaviours. Key findings are that environmental concerns, including knowledge of fuel costs, emissions, or engagement in environmentally sustainable behaviours, are not an important determining factor in heating system choice across the majority of households. No clear trend emerges on the likelihood of specific heating systems being associated with a broad range of socio-demographic variables, including age, income, and working status. Certain building attributes are associated with specific heating system types, with analyses segregated by new build properties, properties with their original heating system, and also by tenure type (i.e. mortgage, rental, etc.). For example, we find public sector landlords' properties have a substantially higher likelihood that the heating system is solid fuel based compared to other heating systems, which identifies an obvious opportunity to target decarbonisation of heating systems.