500,000 homes to be retrofitted for energy efficiency

Government proposal is short on detail but SEAI estimates €30,000 for deep retrofit

Workers install solar panels on a roof. Photograph: Courtesy of Construct Ireland

Workers install solar panels on a roof. Photograph: Courtesy of Construct Ireland


The Government’s announcement that 500,000 houses are to be retrofitted to be more energy efficient will leave many people looking at their own four walls and wondering what exactly will be needed, how long it will take and how much it will cost.

Their proposals, rolled out on Monday, are short on detail and few questions have been answered.

However, the Sustainable Energy Authority of Ireland (SEAI) has a comprehensive guide to retrofitting which outlines what people can expect to happen if they try to improve the energy rating of their home.

It will take time – several months at least – and will cost tens of thousands of euro for many people but, if done well, it will significantly cut down on the energy used in homes while making them feel warmer and more comfortable.

More than a third of a home’s heat can be lost through external walls and that is where many retrofit experts will look first. The three main ways of improving insulation are cavity, external and internal wall insulation.

For homes with cavity walls, insulation is simply pumped into that gap through a series of small holes while external insulation sees the outside of a home wrapped in heavy insulation material and then sealed and re-plastered.

Homes where neither option is practical can be insulated by attaching insulation boards to the inside of the external walls and covering them with plasterboard although this option does see the size of rooms shrink somewhat.

Up to 30 per cent of a home’s heat can be lost through its roof which is why attic insulation is critical. It is also one of the least intrusive elements of retrofitting as it simply sees a thick layer of insulating material rolled over the ceiling below and the water tank and pipework similarly insulated.


With 10 per cent of a home’s energy potentially disappearing through floors, they are typically insulated as part of the process and the approach that will have to be taken will depend on the flooring. A solid ground floor, a suspended concrete floor and a suspended timber floor all require different approaches.

With a further 10 per cent of a home’s heat potentially lost through windows and doors, replacement to modern standards is essential.

As the overall airtightness of your home will be dramatically improved as part of a deep retrofit, ensuring that there is good ventilation is even more important, to improve the indoor air quality and reduce the possibility of any condensation or mould.

Projects will have to include renewable energy solutions. Modern room heating stoves are highly efficient when compared with a traditional open fire and provide three times the heat and use only a quarter of the fuel.

Other renewable energy systems include heat pumps, solar water heating panels and solar photovoltaic panels.Wood chip or pellet boilers, biomass boilers and combined heat and power (CHP) systems are also used.

A deep retrofit will cost about €30,000 or more for bigger, older homes. As it stands, grants of as much as 50 per cent are available for insulation works. More details are available from seai.ie.