#1 The Case for Post Occupancy Evaluation
A conversation between Carrie Behar, Head of Sustainability at Useful Simple Trust and Romy Rawlings FLI FRSA at DeepGreen
Dr Carrie Behar
When it comes to delivering buildings and places, the construction industry rightly prides itself on attention to detail in design quality, sustainability, safety, and increasingly, co-design and user engagement. But one fundamental question is rarely posed:
Does the finished project meet its original aims?
That question is at the heart of Post Occupancy Evaluation (POE), a discipline that remains underused in the built environment despite offering so much vital insight. For this blog, associated with DeepGreen’s Can’t See the Wood for the Trees interview series, I had the pleasure of speaking with Carrie Behar, Head of Sustainability at the Useful Simple Trust, and a longstanding advocate of POE.
I first encountered Carrie’s views on the topic when we served together on the New London Architecture Expert Panel for Wellbeing. Her belief in the value of POE really got me thinking; because when you consider it, the absence of rigorous, routine POE in our projects is hard to justify.
Carrie brings a deeply informed perspective to this conversation. With a background in architecture and environmental design, her PhD research 10 years ago focused on how people adapt to new ventilation systems in their homes; research that relied heavily on POE as a primary tool. Today, she leads sustainability strategy at both corporate and masterplanning level, while also serving on the steering group of Architects Declare. That POE is something she continues to champion across these roles speaks volumes.
“POE is the process of going back to completed projects after they’ve been occupied to learn from the people using them and to measure the real world environmental performance so that we can learn lessons from both in order to improve”
What Is POE and Why Does It Matter?
At its core, POE is a process of returning to a completed building or landscape once it is in use, to gather feedback from occupants and measure actual performance: environmental, functional, and experiential. As Carrie explains, the logic behind POE is strikingly simple. In any other sector, designing and releasing a product without following up to see whether it works as intended would be unthinkable. And yet in construction, astonishingly, it remains the norm.
This disconnect is significant. Carrie notes that buildings often consume two or even three times more energy than they were designed to, pointing to the widespread performance gap that POE can help identify and reduce. Whether the result of flawed design assumptions, value engineering, changes made during construction, or poor commissioning, the reasons for that gap are rarely obvious without post-occupancy insight. POE acts as the bridge between design intent and actual use, helping us understand not only where things go wrong, but also how they might be put right.
“We’re humans, not machines. We’re not predictable. And when humans go into a building or space and start to occupy it there will be some some unexpected outcomes”
More Than a Diagnostic Tool
But POE is not only a mechanism for identifying what went wrong; it’s also a framework for continuous learning. Carrie draws a compelling parallel with snagging: just as we inspect and fix issues identified after handover, so too should we inspect and adjust systems that affect comfort, usability, or efficiency. She argues that POE should be a natural extension of that process, particularly given the variability introduced by human behaviour. No matter how well-designed a space may be, people will use it in unexpected ways, highlighting needs, gaps, and opportunities that weren’t foreseen on the drawing board.
The potential benefits extend beyond the project in question. Insights gained through POE - whether around lighting, HVAC performance, spatial usage, or even user misunderstanding - inform better standards across the sector. And yet, despite the clear logic and long-standing availability of the methodology, uptake remains low. As Carrie notes, POE has been around for 30-40 years but is still rare in most project workflows.
So Why Isn’t POE the Norm?
There are multiple reasons, and none are insurmountable. Primarily, there’s the loss of momentum and budget at the end of a project. By the time a building is operational, most of the team has moved on to the next deadline, the next client., the next ‘new, shiny thing’. Carrie believes it takes a very enlightened client to champion POE, and they must be willing to ring-fence budget even when there’s little contractual pressure to do so. Post-handover, there can obviously also be issues with accessibility.
For clients that plan to sell a building on immediately post-construction (a high proportion), there’s nothing to be gained from conducting POE so there will be minimal interest. However, there is real value to be gained by owner occupiers or those managing building or estates in the longer term, for instance universities, hospitals, or Build to Rent properties.
Then there’s the fear factor. What if a POE reveals uncomfortable truths: underperformance, design flaws, even construction defects? For speculative developers or clients focused solely on delivery to market, that’s a risk they may prefer not to take. As Carrie recounts, thermal imaging during a building performance evaluation once revealed missing insulation, raising difficult questions about responsibility and liability. Not everyone wants to go looking for problems they might then have to solve.
Another barrier is misconception and the belief that POE must be a complex, research-heavy process requiring sensors in every room and wading through huge amounts of data. In fact, a proportionate approach can be just as valuable. A single-day walkthrough, conversations with users, and a quick look at energy bills can yield insights that make a real difference. More comprehensive evaluations can, and should, be built in from the outset on larger or longer-term projects, but they’re not the only valid model.
From Insight to Action: Advancing the Adoption of POE
Despite growing awareness of environmental and social challenges, POE remains an undervalued practice across the construction and property sectors. As Carrie explains, POEs are often still seen as a ‘nice to have’ rather than an essential process. Making POE mandatory, she argues, is critical if we are to bridge the gap between design intentions and real-world building performance.
“Architects Declare has a policy around building performance which also signposts the benefits of carrying out POE on projects, as something that is required in order to deliver net zero buildings in practice”
Policy Momentum and the Role of Standards
Carrie points to promising developments in the UK, such as the UK Net Zero Carbon Building Standard, which mandates post-occupancy data as part of its certification. Only after a full year of operational performance data can a building be verified as ‘net zero in use’. Similarly, the NABERS UK standard, relevant to commercial buildings and adapted from the Australian model, requires verified performance data.
However, current building regulations in the UK still assess compliance only at planning and construction stages, with no post-completion checks. This disconnect means energy performance targets often go unverified, and issues like overheating or poor air quality can persist unchecked.
Beyond the Building Envelope: Addressing Equity
POE isn’t only about energy data. Carrie emphasises its broader role in understanding occupier comfort, usability of systems, and the effectiveness of both internal and external spaces. These human-centric insights - how people feel and behave in a space - are difficult to capture with sensors and meters alone so qualitative feedback is essential.
This connects to wider questions of equity. Carrie raises concerns that higher regulatory standards in London, driven by the Greater London Authority and the London Plan, may create a two-tier built environment. With local authorities outside London lacking the same rigorous planning requirements, deprived communities in particular risk being left with substandard housing. This growing divide, which Carries refers to as ‘housing apartheid’ undermines national ambitions for climate resilience and social justice.
“A big concern is that POE will exacerbate the equity divide we already have between the North and South of the UK. It’s amplified by land prices and the viability constraints of building outside of London, where property prices don’t necessarily justify these additional items unless there’s a policy requirement to do so”
Embedding POE into Practice
To scale up POE effectively, Carrie argues for embedding it in policy so that it becomes mandatory. This would drive consistency in data collection and ultimately enable meaningful comparisons across projects. However, she cautions against reducing POE to energy metrics alone since its true power lies in its capacity to inform holistic, people-focused, and place-sensitive design.
Carrie advocates aligning POE with regenerative design thinking, which demands a far longer-term view by considering the impact of construction on future generations. Rather than seeing POE as a one-off assessment, 1-3 years post completion, we need to use it as an ongoing feedback loop to understand how our built environments evolve, support wellbeing, and affect ecosystems over seven future generations.
Introducing the Handprint Tool
In a step towards integrating POE with regenerative practice, Carrie introduced the Useful Simple Trust’s Handprint tool. This new tool evaluates a project's impact across six themes: climate resilience, carbon, biodiversity, wellbeing, social equity, value, and material use. Inspired by the idea of moving from ‘footprints’ (what we take) to ‘handprints’ (what we give), the tool positions each project on a regenerative-to-degenerative spectrum. While it produces a quantifiable score, its main value lies in fostering deeper team reflection and learning.
As important as carbon is, this holistic approach helps move beyond carbon tunnel vision and encourages a wider consideration of the systems that buildings sit within. With climate events becoming ever more severe, Carrie stresses the need to consider natural systems and community resilience in design outcomes.
Facing 2050: Adaptation vs Mitigation
Looking to the future, Carrie is torn between the imperatives of mitigation and adaptation. While we know we must cut carbon emissions, many UK homes are already ill-equipped to deal with our cold, wet winters and now we’re also facing increasing heat. The rise in domestic air conditioning, once rare in the UK, signals a worrying trend towards carbon-intensive adaptation.
She sees retrofit as a vital strategy, not only to make homes warmer in winter, but more liveable in our hotter summers. However, the UK still lacks incentives and investor interest in deep retrofit. Partly because there’s no ‘one-size-fits-all’ solution and nor does it offer the kind of rapid returns that often attract funding. However, the social and environmental returns could be transformative.
Closing Thoughts
Ultimately, our conversation returns to POE and ends with a call to embed it more firmly into practice. Not as a box-ticking exercise, but as a means to continuously learn, adapt, and improve the places and spaces we create.
“If we don’t learn from each project we deliver, how can we ever hope to do better?”
Coming next month:
Emma Bearman of PLAYFUL ANYWHERE C.I.C. shares her thoughts on how and why our high streets have erased children and how we can reverse this damaging trend.