Replacing Dundee street lights with LEDs has failed to deliver the promised £900,000 a year in savings.
Local authority bosses logged an almost £1 million overspend on city development last year after expected savings from its replacement light programme failed to materialise.
Councillors were told in 2017 the £4.8m scheme to fit more than 18,000 new white LED lights would reduce running costs by around £900,000, as well as cutting carbon emissions.
Councillor Richard McCready (Labour) said handling of the scheme raised questions about the “confidence” councillors could have in the business cases for key projects.
He said: “Officers are often not very happy about their work being questioned in committee.
“We see a situation where a plan that we were told would save us money, actually hasn’t saved us money and it hasn’t worked out.
Mr McCready said the value in the LED scheme may come from the reduction in carbon emissions. Colleagues, however, had been presented with a business case built upon the potential for cost savings.
“Can we, as councillors, have confidence that any business case put in front of us in the future is as robust as it can be?
“I understand there are particular issues around Covid-19 but business cases put in front of us should stand up, be robust and deliver what they say they are going to do.
“When a plan doesn’t do what it is intended to do we are meant to forget about it, walk on, and hope for the best in the future.”
The replacement street lights have also been widely criticised for leaving large parts of the city poorly lit.
The overspend figures emerged as councillors debated the local authority’s annual accounts.
The accounts listed the 12 areas in which the council had overspent against its agreed budget and the 19 areas where it had underspent.
Overall, the council spent £4.753m less than it had planned in its 2019/2020 revenue budget. City Development, however, overspent by £2.6m for the fourth year in a row.
The overspend on LED street lighting and car par security was the third highest. The largest was £1.5m in “under-recovery of fees and charges” related to building services and just 0ver £1m of additional spending on the Integration Joint Board created by an additional demand for health and social care services.
Council chief executive David Martin said: “There is absolutely no problem whatsoever with elected members querying officers’ business plans and our best estimates sometimes, and thorough business cases in others.
“That’s why reports come to elected members for scrutiny. On the particular issue of the LEDs, we have, in fact, brought a report back to tackle that particular issue and elected members thoroughly debated it.”
Figures published in the council’s annual accounts revealed a £990,000 overspend on “LED Street lighting electricity savings not achieved and higher car park security costs”.
Councillor Fraser Macpherson (Liberal Democrats) had similar concerns over the overspend.
He said: “This is almost £1 million. I wonder if we can get some reassurance that this issue will be taken account of in future budgets so we don’t end up with an unrealistic level of expectation on what can be achieved?”