Bringing Northern Ireland’s housing stock up to Energy Efficiency Rating (EER) Band C will cost £2.4bn, experts have estimated.
Measures required to improve the energy efficiency of the 390,000 homes in the region currently below Band C will cost an average of £6,200 per dwelling, according to a new report produced by the Building Research Establishment (BRE) on behalf of the Northern Ireland Housing Executive (NIHE).
Doing so would mean average energy cost savings of £500 a year per home, as well as annual carbon dioxide savings of 3.2 tonnes, the report said.
Owner-occupied homes make up 72% of those below Band C, with 21% private rented and just 7% in the social rented sector.
Improving the energy efficiency of the 26,000 eligible social rented homes would cost an estimated £100m, at an average per-unit bill of £2,900.
In comparison, the estimated per-unit cost for owner-occupied homes is £6,600, with a total sum of £1.9bn for the 281,000 eligible homes.
For the private rented sector, 83,000 homes are estimated to need work to meet Band C standards, at a total cost of £500m and an average per-unit spend of £5,900.
Social housing in Northern Ireland, like the rest of the UK, received huge investment in the 2000s to reach the Decent Homes Standard.
The UK government has set a target to get as many homes as possible up to Band C by 2035, with a specific 2030 target for social housing.
Achieving the higher Band B across Northern Ireland’s stock would mean works to around 586,000 homes at a price tag of £9.2bn, the BRE report found.
That represents an average cost per home of £15,600.
But it would save affected households £700 a year on energy bills, while reducing their carbon output by 3.7 tonnes.
“Generally, traditional improvement measures, which focus on installing fabric insulation and upgrading heating systems, were sufficient to improve dwellings to an EER Band C,” the report said.
“To reach the target Band B threshold, however, further measures were required in the majority of cases.
“Specifically, the installation of photovoltaic (PV) panels was essential in improving a significant proportion of the stock to Band B.”
The cost of bringing all social housing up to Band B was pegged at £1bn, reflecting an average spend of £12,300 to upgrade around 82,000 homes.
The BRE’s analysis is based on data gathered through the 2016 Northern Ireland Housing Condition Survey.