In the complex dance of BREEAM certification, most project managers are laser-focused on material credits, waste management, and energy models. However, there is one critical milestone that isn’t dictated by the contractor or the client, but by the British weather: The Thermographic Building Fabric Survey.
As we approach the warmer months, the window for capturing high-quality thermal data is rapidly closing. If your project is nearing completion, understanding the relationship between physics and BREEAM compliance is essential to avoid a six-month delay in your certification.
The Physics of “Seeing” Heat: The 10°C Rule
A thermographic camera doesn’t actually “see” insulation or air leaks; it detects infrared radiation. To identify a defect in the building envelope, there must be a significant flow of heat passing through it. This requires a temperature gradient—known as the Temperature Differential (Delta T).
For a survey to be compliant with BS EN 13187 (the standard required for BREEAM credits under Man 04 and Ene 01), we typically require a minimum Delta T of 10°C between the internal and external environments.
- In Winter: Maintaining an internal temperature of 21°C against an outdoor ambient temperature of 5°C is easy. The heat “pressurizes” the building fabric, making every missing bat of insulation or leaky window seal glow brightly on the thermal sensor.
- In Summer: If the sun has been beating on the brickwork all day and the night-time temperature only drops to 16°C, even a 22°C internal set-point only provides a 6°C differential. At this level, the “thermal signature” of a defect becomes blurry or invisible. The camera sees a uniform wash of heat, and the survey becomes technically invalid for BREEAM purposes.
The “Summer Wall”: Why You Can’t Just “Wait a Week”
The most dangerous assumption in building thermography is that you can simply reschedule for a “cooler night” in July. Unlike air pressure testing, which can be done in almost any weather, thermography is seasonally locked.
Once we hit the “Summer Wall”, typically between late May and early September, the overnight temperatures rarely stay low enough for long enough to allow the building’s thermal mass to stabilize for a valid reading. If you miss the window in May, you aren’t just delayed by a few weeks; you are often waiting until late October for the weather to turn.
The BREEAM Emergency Exit: KBCN00031
So, what happens if your build schedule finishes in July? Does the credit simply evaporate? Not necessarily. BREEAM provides a “seasonal allowance” under KBCN00031, allowing the Assessor to award the credit based on Evidence of Intent.
However, this isn’t as simple as just placing an order. To secure the credit without a completed survey, you must provide a “Evidence of Appointment” package, which includes:
- A Formal Appointment: Evidence that a PCN-certified Thermographer has been contracted.
- The Technical Justification: A written statement from the surveyor explaining that the current seasonal conditions prevent a valid survey.
- The Scheduled Commitment: A confirmed date for the survey during the next available “thermal window” (the following autumn/winter).
- The Rectification Agreement: A contractual guarantee from the main contractor stating that any defects identified during the future survey must be rectified at their own cost, even if the building is already occupied.
The Commercial Reality: Why “Plan A” is Always Better
While the KBCN00031 allowance is a vital safety net, relying on it is a massive commercial risk.
The “Occupied Building” Nightmare: Imagine discovering a major insulation void or a significant air leak in December, six months after handover. The building is now full of tenants. Carrying out remedial works on the building envelope at that stage is exponentially more expensive, disruptive, and legally complex than fixing it while the site team is still demobilizing. Also bear in mind that preparing for, and undertaking, the survey itself when the building has been handed over and is occupied can be a logistical nightmare.
By booking your survey now, while the temperatures still allow for a 10°C differential, you achieve:
- Immediate Compliance: Close the BREEAM file and secure your credits without lingering “Evidence of Intent” notes.
- Quality Assurance: Identify and fix defects while the scaffolding is still up or the subcontractors are still on-site.
- Operational Efficiency: Ensure the building actually performs as the energy model predicted from Day 1, avoiding “performance gap” complaints from the first winter occupants.
Secure Your Survey Before the Heat Rises
The clock is ticking. As the days lengthen, the window for accurate, compliant thermography is shrinking. Don’t let your BREEAM “Excellent” or “Outstanding” rating be derailed by a warm spell.
Contact our team today to schedule your survey or to discuss how we can help you manage your BREEAM evidence requirements if you’re hitting the Summer Wall.