It will be the first country in the UK to implement the initiative, assessing home loans against the energy efficiency of the property being bought.
The Welsh Government has worked with the Building Research Establishment on the LENDERS project which modelled the work, with the maximum mortgage offered varying by as much as £11,500 between the most energy efficient and inefficient homes.
The change will come into effect next month.
Housing and Regeneration Minister Rebecca Evans said: “From this June, the Help to Buy-Wales equity loan affordability calculator will include an energy efficient element. This means when people look to see how much they can afford, they will be given different options depending on the energy efficiency of the property they are looking to buy and loans will be adjusted according to the energy rating of the home they choose.
“A more energy efficient home costs less in bills so buyers will potentially be able to afford to borrow more. We know that energy spending can be a major household outgoing, which is why we want to make energy efficiency part of the consideration when people look to buy a home in Wales.”