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Tom Garrigan, Executive Director at BSRIA says combining accurate building data with occupant insights can deliver retrofit programmes that are evidence-based, cost-effective, and resilient
With 85 per cent of the buildings that will be in use by 2050 already built, decarbonising the UK’s built environment has become one of the most urgent and complex challenges facing facilities managers.
But with the UK’s complex regulatory landscape and some of the oldest building stock in Europe, there is no one-size-fits-all approach. Instead, we must adopt data-led, assessment strategies that consider the requirements of every building individually to inform the decision-making process.
This requires a change of mindset: one that prioritises performance and compliance, but also long-term resilience and occupant wellbeing. As Dame Julia King noted at the recent BSRIA Briefing: “Reaching net zero is no longer enough; we must adapt our buildings to avoid them becoming uninhabitable.”
The scale of the challenge is significant, and so is the opportunity, with the decisions made today defining the buildings of tomorrow.
FROM ASSUMPTIONS TO ASSESSMENT
Robust decarbonisation is not something that can be estimated; it requires an accurate data and assessment approach. This means that a successful decarbonisation strategy should always begin with investigation, not intervention. Before any retrofit works are planned or resource is committed, a building must be fully understood, including how it performs, how it is used, and how occupants experience it.
This process should involve a combination of non-invasive techniques, including thermal imaging, airtightness testing, acoustic analysis, and, crucially, post-occupancy evaluation. When analysed together, this data builds a holistic view of building performance by identifying inefficiencies, inconsistencies, or risks that may not be visible at surface level.
What this achieves is twofold. Firstly, it enables targeted retrofit investment, which avoids the waste and disruption of unnecessary upgrades. Secondly, it improves project outcomes by ensuring that any interventions align with the actual usage and performance of a building, rather than being based on assumption.
However, to ensure a truly holistic approach, the assessment process should also include input from the people who use the building regularly. Occupant engagement through surveys, interviews, or open communication can highlight comfort issues, behavioural trends and operational constraints that non-invasive measurements alone might not capture. This collaborative approach not only uncovers deeper insight to assess the improvements required, but it also encourages users to become active participants in achieving operational sustainability targets.
ASSESSMENT IN PRACTICE
We applied this methodology during the recent retrofit of our own headquarters, BSRIA House. Rather than opting for broad, generic improvements, we adopted cost-effective rapid fabric assessments to provide a full picture of the building’s baseline performance and the starting conditions. This allowed us to identify specific, high-impact areas for retrofit works that would deliver maximum value while avoiding unnecessary disruption.
The outcome of this was a more meaningful retrofit that substantially improved energy efficiency and operational performance. We achieved a 35 per cent reduction in building airtightness, a 28 per cent reduction in Scope 1 and 2 emissions and a 14 per cent increase in occupation satisfaction scores, all while the building remained fully operational.
This demonstrates how targeted retrofit based on measurement assessment and evidence can be far more cost-effective, less invasive and more impactful than relying on standardised solutions. It also shows the importance of doing the groundwork first: measuring, testing, and listening, before acting.
