Grants for upgrading oil and gas boilers to more efficient models end in the next few weeks and new grants for conversion to electric heat pumps are due to be rolled out in April.

However, the Department of the Communications, Climate Action, and Environment says it expects it will only help around 1,200 home-owners a year with grants. At that rate it would take 583 years to complete the conversion unless householders take the initiative and bear the full cost themselves.

The Green Party says the scheme is woefully inadequate to address the problem of carbon emissions from residential heating.

Energy spokesman and Dún Laoghaire councillor Ossian Smyth said: “We have a huge dependence on oil and gas and we need to switch away from that but if we’re looking at switching 1,200 a year, that’s not a plan.”

Heat pumps — which extract ground heat or external air and condense it to raise the temperature — are becoming more common in new buildings but retrofitting existing homes costs €10,000-€15,000 for the basic installation, while extensive insulation and pipe replacement also often has to be carried out at additional cost.

Grants for approved works will run to €3,500 while grants for external wall insulation are being increased to a maximum of €6,000 for detached houses but that still leaves much to be paid by the homeowner.

Running costs are lower than oil and the Sustainable Energy Authority of Ireland (SEAI) has calculated that more than half of households should be able to make their money back in savings over 11 years, although the pump will need replacing a few years later.

While the department says it has no short-to medium-term plans to place an outright ban on oil-fired heating — unlike Denmark and Norway — the State is under growing pressure to tackle carbon emissions from all sectors. Households account for 25% of all emissions in the country and 30% of that is from oil-fired central heating.

Michael Manley, one of the most senior officials in the Department of Climate Action, told an energy seminar recently that home heating “has to come and will come into focus”.

“We have over 700,000 oil-fired heating systems — it’s difficult to see those still operating in years to come and easily reconciling with our climate change ambitions,” he said.

Mr Smyth said a range of switching options and incentives needs to be put in place urgently.

“There is an obvious case for solar panels,” he said. “We have all this roof space in Ireland not being used and it could be heating homes and supplying the excess electricity to the grid but there is no system in place for that.”

Taxpayers will bear the brunt of fines of up to €600m a year from 2020 onwards for the country’s failure to meet EU obligations to reduce carbon emissions.

“Does the Government prefer that we pay those fines than that they bring in schemes to save energy? It doesn’t make sense,” said Mr Smyth.

The department said there is no set budget for the grants scheme — although Climate Action Minister Denis Naughten said at the time of its announcement that it, plus the insulation grants, would cost about €3m a year.

The Climate Action Department said it would be “demand led”.

“The Greener Homes Scheme which ran from 2006-2011 grant-aided an average of 1,200 heat-pumps per annum. A similar level of activity is possible once the scheme rules are defined and the market responds accordingly,” it said.