The Green Party has committed to spending €50bn on retrofitting homes over the next 20 years.
The party says it would also look at replacing the social welfare system with a non-means-tested Universal Basic Income if in government.
It will also merge the contributory and non-contributory State pensions and create a tax credit for part-time workers.
The party says: "Overruns in spending, delays in the delivery of the National Children's Hospital, and ever-increasing waiting lists have seriously harmed the welfare of patients and service users, as well as hitting people in their pockets.
"We believe that health policy is best addressed through cross-party consensus and therefore support the Sláintecare plan and commit to adequately funding healthcare reform through that framework."
The party is pledging to reduce the country's overall energy demand with a combination of technological advances, regulatory decisions and positive behavioural change.
It also wants to invest in public transport, walking and cycling "at a much higher rate" and give commuters alternatives to driving private cars.
— Seán Defoe (@SeanDefoe) January 25, 2020
It also says it would provide free public transport for students and pilot a €365 annual public transport pass.
While 20% of the transport budget will go on walking and cycling projects.
Party leader Eamon Ryan has said he will not promise people tax cuts - but instead focus on increased investment in housing, health and public transport.
He thinks there needs to be a massive investment in order to drive a move away from fossil fuels.
"We should start also - everyone agrees on this in the Dáil, it's one of the areas where there isn't disagreement - that we need to retrofit those 1.5 million homes.
"It's a project beyond compare in scale.
"What's it going to cost? €50bn over the next two decades.
"'That sounds a bit over the top' - but if we're to stop burning fossil fuels, that's what we need to do".
And the party has big plans for renewables - with targets for 700,000 solar panels on Irish homes.
Read the full manifesto here