We model buildings with precision: daylighting, thermal loads, smart control strategies.
But once people move in, something shifts. Systems get overridden. Windows stay open in winter. Spaces are adapted for life, not for the model. The result? A performance gap that’s not technical, but behavioural. And if we don’t design for it, we’ll keep losing the performance we think we’ve delivered.
1. When Design Meets Reality
The behaviour gap — the chasm between intended and actual use — is one of the most persistent failures in architecture, engineering, and sustainable development.
No matter how intelligent the system, it’s still subject to human impulse:
- A thermostat taped over because someone’s too cold.
- Automated blinds disabled for privacy.
- Ventilation systems bypassed by a window propped open.
From high-end office buildings in Asia to retrofitted social housing in the UK, the story repeats itself: models don’t match reality. Not because the physics failed — but because people used the space differently than expected.
2. Two Real-World Lessons
The London Smart Cladding Project
In a recent project, our team developed a responsive façade system for a residential block in London. It dynamically adjusted glazing ratios based on light and occupancy — and simulations projected a 45% reduction in heat loss during winter.
But post-occupancy monitoring told a messier story.
Some residents used the system as designed. Others didn’t:
- Leaving glazing permanently open for airflow or personal preference.
- Closing it entirely for perceived security.
Result: real savings varied widely. Some flats underperformed, others barely improved.
The conclusion? If user behaviour isn’t embedded in the simulation phase, even the most advanced systems will underdeliver in practice. The behaviour gap isn’t a side note — it’s the story.
The Bullitt Center, Seattle
One of the greenest buildings in the world. Net-zero ambitions.
And still, in its early years, it struggled to hit its energy targets.
Why? People didn’t use operable windows or blinds as expected. Design assumptions didn’t align with lived behaviour.
Only after the team worked closely with occupants — through training, feedback loops, and transparent dashboards — did the building begin to meet its promise.
It wasn’t about redesigning the tech. It was about redesigning the relationship.
3. Why the Behaviour Gap Matters More Than Ever
As climate regulations tighten and cities edge toward performance-based standards, this isn’t just a nuisance — it’s existential.
Ignoring behaviour puts us at risk of:
- Regulatory failure
Buildings that look compliant on paper but fail in practice. - Occupant dissatisfaction
Discomfort, distrust, and workaround behaviour that kills system performance. - Wasted investment
Smart tech that doesn’t account for real use becomes a stranded asset. - Reputational damage
Developers and cities lose trust when green claims don’t hold up.
In vulnerable regions, especially those facing heat stress or energy poverty, these failures are not abstract. They become public health crises, deepening inequality instead of solving it.
4. Designing With Behaviour in Mind
So what do we do?
We shift from idealised control to resilient adaptation.
From assuming compliance to designing for divergence.
Here’s how:
- Engage early and often
Include users in co-design, scenario mapping, and decision-making. Don’t guess what people will do — ask, observe, anticipate. - Build a culture of post-occupancy evaluation (POE)
Not a checkbox. A feedback loop. A living archive for learning, adjusting, evolving. - Embrace adaptive, human-centred systems
Interfaces and controls must allow for flexibility, not enforce rigidity. - Pair data with ethnography
Sensor readings tell you what happened. Ethnography tells you why. Use both. - Treat buildings as living laboratories
Encourage ongoing participation — from facility teams to residents. Make performance a shared experience, not a silent metric.
This isn’t about overengineering for every outcome.
It’s about designing buildings that don’t break the moment humans walk in.
5. The Stakes Are Real
If we fail to close the behaviour gap, we don’t just waste energy.
We risk:
- Losing credibility in sustainable design
- Undermining climate policy
- Alienating the very people these spaces are meant to serve
As the London project showed, even brilliant systems falter without behavioural integration.
As the Bullitt Center proved, empowering users changes everything.
Because in the end, no matter how smart our systems get —
Reality always wins.
The Future We Must Design For
The future of sustainable buildings won’t be model-perfect.
It will be human-perfect: adaptive, forgiving, and grounded in how people actually live.
If we want better buildings, we may not need smarter tech —
We need smarter empathy.
Let’s Rethink How Buildings Perform — with People in the Loop
At BRUSEGROUP, we help cities, developers, and design teams translate behavioural insights into design strategies that hold up in real life — not just in simulations.