The London Office of Technology & Innovation (LOTI) and the Greater London Authority (GLA) are pioneering a data-driven approach to improving housing conditions across the city. By deploying Internet of Things (IoT) sensors, London boroughs are now able to proactively identify and address damp and mould issues—before they escalate into serious problems. This initiative marks a shift from reactive housing maintenance to a preventative model, improving both living conditions and operational efficiency.

From Reactive to Proactive

Damp and mould in homes are more than just an inconvenience – they pose significant risks to respiratory health and general well-being. Historically, councils have relied on tenant complaints or visual inspections, meaning that many cases were only addressed when they had already become severe. The IoT sensor project changes this, enabling councils to monitor environmental conditions in real-time and intervene earlier.

By capturing data on temperature and humidity levels, the sensors create an early warning system for damp and mould risks. The goal is not just to fix issues but to prevent them altogether, reducing costly repairs, minimising disruption for residents, and ensuring healthier homes for thousands of Londoners.

Implementation lessons 

The project has rolled almost 200 sensors that were distributed across 16 boroughs, allowing councils to experiment with different deployment approaches. The collaboration included a further 4 boroughs who shared insights and expertise from their own sensor deployments. Some boroughs targeted properties with historical damp issues, while others focused on temporary accommodation or older housing stock in need of investment. This diverse approach to deployment has allowed us to collectively test a number of use cases and begin to track the emerging benefits alongside the challenges that might impact scaling in the future, those findings are summarised below with the full detail available in IoT Sensors for Damp and Mould Project: A Comprehensive Review.

The benefits of using IoT sensors to support dealing with damp and mould

We identified a number of areas where sensors have demonstrated their value in supporting boroughs deal with damp and mould:

1. Early Warnings and Risk Prediction

• IoT sensors have provided real-time risk assessments, identifying at-risk properties before damp and mould develop into severe cases.
• Automated alerts enabled councils to act quickly, reducing the likelihood of expensive repairs and potential health risks to tenants.
• Councils using a proactive model reported a 40% reduction in severe cases, as they were able to intervene early.

2. Insights Into Root Causes

• The data has highlighted that fuel poverty plays a major role in damp and mould issues, as some tenants are unable to afford heating, leading to cold, damp environments.
• Structural issues such as poor insulation, aging housing stock, and inadequate ventilation were frequently identified as underlying causes.
• By combining sensor data with other datasets, councils gained a holistic understanding of property risks, making it easier to prioritise long-term investments in maintenance and repairs.

3. More Efficient Housing Management

• Sensor-based monitoring has reduced the need for repeat property inspections, allowing housing officers to focus on high-priority cases.
• Predictive maintenance strategies, informed by sensor data, are being tested to plan interventions before problems arise.
• Some boroughs, like Barnet, reported an estimated 25% reduction in damp and mould-related callouts after integrating sensors into their processes.

4. Stronger Resident Engagement

• Several councils have shared sensor data directly with residents, leading to increased awareness and preventive behaviours.
• In half of the properties where alerts were triggered, residents took corrective actions after engaging with housing teams.
• Barnet’s Resident App, which provides real-time sensor insights and tailored advice, has improved tenant trust and engagement.

5. Financial Savings and Long-Term Impact

• While still early in the project, some boroughs have completed provisional assessments that estimate annual savings of up to £8 million by scaling IoT sensors across their properties.
• The most significant financial benefits come from avoiding severe cases, reducing legal claims, and minimising costly tenant relocations.
• The project is proving that a small upfront investment in IoT technology can lead to substantial long-term savings and better housing outcomes.

Benefits in Context

Boroughs shared insights into how sensors aided the work of identifying and dealing with damp and mould

1. Early Identification and Prevention

Councils have been able to detect damp and mould risks much earlier than ever before. Instead of waiting for tenant complaints, they can now proactively monitor and act on warning signs, preventing serious issues before they arise.

“If we can see the issue before it’s arising, we can treat it as a repair. The resident doesn’t have to do anything—they don’t even have to pick up the phone.” – Hounslow Council

2. Better Support for Vulnerable Residents

IoT sensors have helped councils identify cases of damp and mould that residents may not have reported. This has been particularly beneficial for vulnerable tenants, including older individuals and those experiencing fuel poverty.

“Sensors have helped us identify people living in properties at risk of fuel poverty, allowing us to provide the right support.” – Islington Council

3. Diagnosing Root Causes and Improving Repairs

Instead of relying on guesswork, councils can now use sensor data to diagnose the root causes of damp and mould—whether it’s poor ventilation, faulty heating systems, or insulation issues. This ensures that repairs are not just quick fixes but long-term solutions.

“We used sensors to understand the tricky cases where mould kept coming back. We found out what was really going on—whether it was due to property issues or fuel poverty.” – Redbridge Council

4. Reduced Inspections and More Efficient Housing Management

Previously, councils often conducted multiple inspections to monitor damp and mould conditions. With IoT sensors, many of these visits are no longer necessary, freeing up time and resources for more urgent cases.

“We don’t have to visit properties as often, and we’re seeing fewer repeat cases where we’ve installed sensors.” – Ealing Council

5. Stronger Resident Engagement

By sharing sensor data with tenants, councils have been able to improve communication and build trust. Residents are also more likely to adjust their behaviour when they can see the direct impact on their living conditions.

“We didn’t want this to feel like ‘Big Brother’ surveillance. Instead, we wanted residents to be part of the process—helping them understand what’s happening in their homes and how small changes can prevent damp and mould.” – Barnet Council

Challenges and Lessons Learned

Despite its successes, the project has faced some challenges:

• Interpreting and operationalising sensor data – Some councils initially struggled to determine the best way to respond to alerts. A clear process for triaging and acting on sensor insights is essential.
• Resident participation – Some tenants were hesitant about installing sensors due to privacy concerns. Councils found that clear communication and transparency helped build trust.
• Fuel poverty and structural issues – In some cases, damp and mould are linked to broader systemic problems, such as poor insulation or tenants not being able to afford heating. While sensors help identify these cases, addressing them requires wider policy interventions.

What’s Next? Expanding the Impact

To build on the project’s success, LOTI and GLA are working on several key next steps:

• Continuing the project through winter months to gather more data on seasonal damp and mould risks.
• Scaling up deployment by testing larger numbers of sensors across different property types.
• Enhancing data integration by combining sensor data with other housing datasets to provide even deeper insights.
• Strengthening resident engagement through apps and communication strategies that empower tenants to take preventative actions.
• Working with strategic leadership to understand the required resources to deploy sensors at scale and adapt processes to make the most of predictive insights as part of repairs and maintenance processes.