The cost of a controversial £1.4m swimming pool revamp plan, which saw councillors divided over whether it could afford it,  looks set to rise by almost half a million pounds.

Richmondshire District Council’s corporate board has given the thumbs up to borrowing £462,000 to cover numerous extra costs and schemes as part of the first major upgrade of Richmond’s swimming pool in three decades.

Last year a £1.4m scheme was approved by the council chairman’s casting vote after it emerged the cost would equivalent to a third of the annual council tax income of the authority.

A meeting of the authority’s leading members heard the additional costs had since arisen due to inflation of £108,000 because of the “crazy” state of the building industry, and to cover £104,000 of more improvements to the building’s fabric.

Members were told while the scheme remained at the design stage a further £125,000 was needed after a survey identified the air handling system needed replacing and another £125,000 to install an air source heat pump to improve the facility’s carbon footprint.

The Green Party and Independent councillor Leslie Rowe called on the authority to provide more details of the proposed improvements, so elected members could ensure “the people who use the pool are actually going to get some benefit out of this rather than just upgrading things that won’t be seen or upgrade the service for the customers”.

He said: “We do need more details exactly what this, originally £1.4m, is going to be spent on and now we have an additional £462,000.

“You are suggesting an air source heat pump for £125,000, which is about 13 times what it costs a household. Given the amount of land that’s around the swimming pool surely a ground source heat pump would be much more efficient to boost the energy of the area.

“It would be helpful if we had some discussion and debate about what’s actually being done to the swimming pool and we could actually try and get value for money as well as an improved and longer lasting swimming pool.”

Conservative councillor Ian Threlfall questioned the wisdom of upgrading the pool’s heating system just three years after efficient gas boilers had been introduced at the pool.

He said: “I am concerned that this is just going to roll on and roll on.”

The authority’s corporate director Colin Dales said he had been working closely with specialist consultants, who had been made aware of the council’s climate change aspirations.

He said while plans to install solar panels to provide energy for the pool had been deemed effective, ground source heat pumps and wind turbines had been ruled out due to numerous issues.

Mr Dales said an air source heat pump would save about 40,000kg of carbon dioxide a year.

He added: “I have gone to great pains to make sure we explore any additional measures that could be taken as part of the pool improvements that are affordable. Some mechanical engineering specialists have been brought in to assist us in that respect.”

Before the extra cost was unanimously approved, the authority’s leader Councillor Angie Dale said: “I think the pool is essential for the residents of Richmond and anything that we can do to bring it up the future all singing and dancing it is a lasting legacy for the residents of Richmondshire.”