New figures from the Central Statistics Office show that households with better energy ratings consumed both less gas and electricity per square metre.
Homes with better energy ratings used less gas per square metre of dwelling floor area, the CSO said, but they were larger in terms of floor area.
Average gas consumption per square metre in 2021 varied from 87 kWh for A and B rated homes, 100 kWh for C rated dwellings, 112 kWh for D rated dwellings, 118 kWh for E rated dwellings and 120 kWh per square metre for F or G rated homes.
The CSO noted that households constructed in 2005-2021 used 93 kWh per square metre compared with 112 kWh per square metre for dwellings built in 1900-1966.
Today's figures show that average gas consumption per dwelling varied considerably more by household type than by energy efficiency rating.
The mean gas consumption by detached houses was 15,906 kWh in 2021. This was 84% higher than the mean gas consumption by apartments of 8,664 kWh.
The CSO also said that the mean gas consumption was lower in 2021 than in 2020 for all household types, which it said may have been influenced by fewer people working from home in 2021 as Covid-19 restrictions eased.
The decrease in average consumption varied from 1.5% for detached houses to 2.7% for semi-detached houses.
But the CSO said the figures for 2021 were all higher than the average for each dwelling type in 2019.
Meanwhile, today's CSO figures show show that homes with better energy ratings used less electricity per square metre of dwelling floor area.
Average electricity consumption per square metre in 2021 varied from 42 kWh for A and B rated homes, 75 kWh for C rated dwellings, 79 kWh for D rated homes, 79 kWh for E rated dwellings and 67 kWh per square metre for F or G rated dwellings.
The CSO said these figures are well below the average gas consumption per square metre reflecting that electricity is used less than gas as a main space heating fuel.
It also noted that the mean electricity consumption per square metre in 2021 was lower for newer dwellings.
The mean electricity consumption in 2021 for dwellings built in 2005-2021 was 48 kWh per square metre compared with 75 kWh per square metre for dwellings built in 2000-2004.
The CSO said the mean electricity consumption was lower in 2021 than in 2020 for apartments (-3.1%) and mid-terrace houses (-1.6%).
It was higher for end-of-terrace (1.6%), semi-detached (2.6%), and detached houses (6.2%).
Average electricity consumption per dwelling also varied considerably more by household type than by energy efficiency rating.
The mean electricity consumption by detached houses was 8,039 kWh last year - 70% higher than the mean electricity consumption by mid-terrace houses of 4,740 kWh.
