Owners would have to declare buildings left vacant for more than a year.

Owners of office buildings left empty for more than a year will be required to declare them on a public register under plans announced by ministers on Thursday, in an effort to bring thousands of square metres of vacant commercial space back into use as housing.

The Empty Buildings Register, set out in a draft bill published by the housing ministry, would cover all offices above 500 square metres in the region. Owners would have to report the floor area, the date the building was last occupied and any plans for its future use. Failure to register would carry fines of up to £25,000, and buildings that remain empty for more than three years could face a sharply increased business rate.

Housing Minister Lucia Farrant said the register would for the first time give councils and developers a clear picture of how much space is sitting idle. “We have families on waiting lists for years while entire office blocks in the middle of Calder have their lights off,” she said. “We cannot fix what we cannot see.”

How much space is empty?

No one knows precisely, which is part of the problem the register is meant to solve. A survey commissioned by City Hall last year estimated that around 18 per cent of office floor space in central Calder was vacant, much of it in older buildings around the station quarter and along the canal that have struggled to find tenants since the shift towards home working. Port Selwyn and Ardle report lower but rising vacancy rates.

Housing campaigners say a significant share of that space could be converted into flats. A study by the Calder Housing Forum identified 42 buildings in the city centre that had been empty for more than two years and which, it said, could provide around 1,800 homes if converted.

“Some of these buildings have been empty for so long that pigeons are the only tenants,” said Rashida Mbatha, director of the Calder Housing Forum. “A register won’t build a single home on its own, but it ends the excuse that nobody knows where the empty space is.”

Owners push back

Property owners have reacted with caution. The regional property federation said it supported more homes but warned that many vacant offices were empty for good reasons – awaiting refurbishment, tied up in legal disputes or unsuitable for conversion because of deep floor plates and poor natural light. A blanket penalty on vacancy, it said, could push owners to demolish rather than convert.

Graham Ostrowski, a director at a firm that manages several office blocks in the station quarter, said converting older offices was often more expensive than people assumed. “You need new windows, new plumbing in every unit, fire escapes, sound insulation,” he said. “Some buildings work beautifully. Others simply don’t, however much the government wishes they would.” The housing ministry says the register itself would not compel conversion, but would be used to target support. Alongside the bill, ministers announced a £30m fund to help owners and housing associations with the cost of converting suitable buildings, offering loans of up to £2m per scheme.

A test in the Assembly

The bill’s fate will depend, as ever, on the arithmetic of the Assembly, where no party holds more than 24 of the 61 seats. The governing coalition can count on around 30 votes, leaving it reliant on support from smaller groups or the two independents representing the hill towns. The independents have signalled conditional support. One of them, Brendan Hallworth, said he would back the bill only if it was extended to cover empty homes and second homes in rural areas, where he said the housing pressure was just as acute. “Empty offices in Calder are a problem,” he said. “Empty cottages in the hill villages are a problem too, and nobody seems in a hurry to count those.”

The opposition said the plan was too timid, arguing that councils should be given powers to take over long-term empty buildings compulsorily. Ministers have ruled that out for now. The draft bill is open for consultation until the end of January. If passed, the register could be in place by next autumn, with the first entries published online within six months.