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A trial which saw high-tech “damp and mould sensors” installed in homes across London has demonstrated that the technology could be scaled up to help tenants tackle poor conditions in their properties, according to an official evaluation of the project.
The £120,000 pilot scheme, led by City Hall and the London Office for Technology and Innovation (LOTI), supported 16 boroughs with the installation of 155 environmental sensors across their council housing stock.
The idea behind the project was that the sensors would monitor temperature and humidity conditions and provide an ‘early warning system’ to prevent damp and mould from building up.
The devices were highlighted by mayor Sir Sadiq Khan during his re-election campaign last year, and were mentioned in his manifesto.
He said at the time: “If this pilot is successful, I want to roll out thousands of mould sensors all across London, to ensure tenants can hold their landlords to account.”
An evaluation of the scheme, conducted by LOTI and highlighted by the mayor in answer to a recent question from the London Assembly, found that the sensors “allowed councils to identify at-risk properties earlier, shifting from reactive to proactive management”. This in turn “reduced the likelihood of severe cases, costly repairs, and tenant relocations”.
In addition, the devices allowed for a “more efficient use of housing officer time”, as “remote monitoring reduced unnecessary inspections and repeat visits, enabling housing teams to focus on high-priority cases”.
Asked whether these positive results mean Sir Sadiq will now provide further funding to ensure “thousands” more sensors can be installed across London, the mayor’s office did not directly respond. They insisted however that he was “committed to expanding” the sensors’ use and would “promote” the technology, in the hope that boroughs and housing associations choose to invest in the devices.

A City Hall spokeswoman said: “The mayor is committed to expanding the use of damp and mould sensors across London, to improve housing standards and ensure tenants can hold their landlords to account.
“He provided £10,000 funding to support the [pilot] project through the winter and will continue to work with boroughs and housing associations to promote this cutting-edge technology to help create a better, fairer London for everyone.”
Aside from the pilot scheme’s more positive results, the sensors’ evaluation report admitted that the devices only provided a “partial picture”, because they “lacked data on other critical factors like boiler usage or ventilation”.
In addition, gaining access to residents’ homes in order to install the sensors is said to have “proved challenging, as many residents were reluctant to engage, hard to contact, or unavailable”.
A Hackney Council representative told LOTI: “It’s been hard to get the damp and mould sensors in… Some people just don’t want to engage with the council, the response is ‘leave me alone’, people say they don’t know when they’re going to be home, just not playing ball.”
The fact that the project didn’t initially cover most of the winter months was also a “limitation” for the pilot scheme, the evaluation noted.
“Due to delays to the start of the project, delivery largely took place during the warmer months, from around April to December, when damp and mould issues were much less prevalent,” according to the report. “This meant councils struggled to make relevant inferences in the timeframe or test the sensors during peak damp and mould conditions.”
However, the extra £10,000 from Sir Sadiq’s office meant that the project was in fact able to continue through the winter months, up to the end of the financial year in March 2025.