Green mortgages are discounted fixed rates available to borrowers buying or building energy-efficient homes.
AIB and Bank of Ireland already offer them.
Ulster Bank’s new four-year green mortgage rate undercuts its existing four-year rate of 2.6pc, which it says is the lowest in the market for that home-loan term.
Head of home-buying Lorraine Costelloe at Ulster Bank said climate change is the defining challenge of our lifetime and the bank wants to incentivise customers who are looking to buy a more energy efficient home.
“Like all of our other fixed rates, the Green Mortgage is open to both new and existing customers as long as the home they are buying or own has a BER rating of B2 or higher.
The advent of green mortgages means homeowners can save money on their mortgage as well as their heating and electricity bills if they choose a sustainable, energy efficient homes.
Bank of Ireland offers discounts of 0.2pc off any of its fixed rates, which range from between one year and 10, for those who qualify for a green mortgage.
Last month AIB launched a suite of green mortgages with rates based on loan to values.
The five-year fixed rates are between 2.35pc and 2.25pc. This is down from 2.45pc.
The emphasis on discounted green mortgages comes as Spanish-owned Avant Money has shaken up the market with the first sub-2pc mortgages here for more than a decade.
It launched this week with the lowest rates in the market at 1.95pc.