A whole life carbon analysis of the Irish residential sector - past, present and future

Abstract

The residential sector is targeted for emission reduction in the climate action plans of many countries. These plans typically focus on reducing the operational energy of the residential sector only, with little focus on the embodied emissions of its construction. To fully decabonise the residential sector both operational and embodied carbon emissions would need to be eliminated.

This paper presents whole life carbon quantification of the Irish residential sector, which aggregates the carbon emitted in operating the national housing stock, as well as the carbon emitted year on year in building and maintaining it. A detailed methodology is presented for both baselining, and forecasting, the emissions due to the residential sector. Operational emissions from space heating, hot water provision and electricity usage in the home are amalgamated. Embodied emissions, which are distributed across almost all categories of the national carbon inventory, are also estimated. The whole life carbon emissions of the residential sector account for approximately 25% of the total GHG emissions reported in the national carbon inventories.

Modelled forecasts to 2030 are presented for national plans that aim to reduce emissions through retrofit and electricity decarbonisation, but will result in increased embodied emissions through planned housing development. The current Climate Action Plan for reduction of residential sector operational carbon fall short of achieving sectoral target reductions. Additional measures will be required if the sector is to meet its proportional share and sectoral emission ceiling. Even if these are achieved, gains that might accrue from home retrofit and electricity decarbonisation will be negated by the growth in embodied emissions deriving from housing development outlined in government plans, when the sector is considered from a whole life carbon perspective.

Forecasts for operational emissions including business as usual and national sectoral targeted reduction scenarios of 40% are outlined. A range of scenarios are then presented to achieve emission reduction across the whole of the residential sector in line with the national 51% reduction targets. These will require; strategic targeting of the worst performing homes for retrofit first, complete decarbonisation of electricity, reduction in the size of future homes, as well as a major reduction in the embodied carbon of building materials used for residential construction. Activation, and renovation, of existing and vacant properties could accelerate the number of homes available while offsetting the need for extensive new construction.