HOMEOWNERS have added almost 10pc to the value of their homes by investing in more efficient heating systems and installing insulation.
Economic think-tank the ESRI says the most energy-efficient homes listed for sale attract a price premium of 9.3pc over comparably-sized properties without upgrades – and commanded rents which were 1.8pc higher.
Since January 2009, all buildings offered for sale or letting must give information on energy efficiency, which is called a building energy rating (BER).
The ratings are based on a 15-point sliding scale from G to A1, where A1 is the most efficient, meaning the property is warmer and cheaper to heat.
Researchers examined the asking price of 36,000 homes for rent or sale on property website Daft.ie, and found that making changes resulted in higher asking prices.
They found that even minor upgrades which changed the rating from a D3 to a D2, D2 to D1 or D1 to C3, added value to the property.
"If you're moving from D1 to C3, and you're talking about the same type of properties in the same location, it's 1.3pc more valuable," researcher Ronan Lyons said.
"The fact you can save money on your energy bills hasn't encouraged people to retrofit their homes. It's taken grants to do that. This is another reason to retrofit.
'The Value of Domestic Building Energy Efficiency – Evidence from Ireland' research was co-authored by ESRI researchers Marie Hyland and Sean Lyons.
It made three findings: energy efficient homes commanded higher rental and sales prices; homeowners placed a greater value on efficiency than renters did; and upgraded, or retrofitted homes, tended to sell quicker.
As many as 250,000 properties have been retrofitted, the Sustainable Energy Authority of Ireland (SEAI) said.
"More than 400,000 homes also have a BER, or one in four, so there's a lot of awareness about it," chief executive Dr Brian Motherway said.
"If you do a gold standard retrofit, costing maybe €20,000, you're talking about a 20 year payback.
"Typically, most are between €3,000 and €5,000, and that's about a six-year payback in savings on your energy bills. But you've added to the value of your home, so the payback is instant."
Grants to pay for upgrades are available, and SEAI is funding works on some 500 homes every week.