Phoenix Journal · Ductwork
Cheap, always-on sensors are shifting building maintenance from fixed schedules to live, condition-based decisions - here is what that means for cost, air quality and kitchen extract compliance.
Building maintenance
For decades, keeping a building safe and comfortable meant working to the calendar - service the plant in spring, clean the ductwork in autumn and hope nothing failed in between.
That model is quietly being replaced. Small, low-cost sensors now sit on fans, filters, motors and inside ductwork, streaming readings to a dashboard around the clock. Instead of guessing when a part is tired or a duct is dirty, you get a signal the moment something drifts from normal. The industry calls it condition-based maintenance, and it is changing how facilities teams plan work, spend budgets and prove compliance. The UK is well into this shift: Britain accounted for roughly a fifth of Europe's industrial IoT revenue in 2023, and more than half of larger operators now treat predictive maintenance as a core strategy rather than an experiment.
For anyone responsible for a commercial kitchen, a busy office or a multi-let building, it is worth understanding what these sensors can and cannot do - because the technology is genuinely useful, but it does not replace hands-on cleaning or formal testing. It simply tells you where to point them.
What the sensors watch
Most building sensors track a handful of simple physical signals that, read together, reveal the health of a system. On air handling and extract plant, that usually means fan motor current draw, vibration, bearing temperature and - crucially - differential pressure across filters and grilles. When a filter loads up or a duct starts to narrow with grease, the pressure difference climbs. A sensor can raise a work order the moment loading passes a set threshold, rather than when the calendar says the filter is due. That single change - from time-based to condition-based triggers - is the heart of the whole approach.
Alongside the mechanical signals sit environmental ones. Sensors for carbon dioxide (CO₂), fine particulate matter (PM2.5), volatile organic compounds and humidity give a direct read on whether ventilation is actually doing its job. A meeting room where CO₂ creeps up through the afternoon, or an extract canopy where airflow has quietly dropped, shows up as a trend on a screen long before anyone complains of stuffiness or smells. In a kitchen, falling extract airflow is often the first hint that grease is building where you cannot see it.
The good news for older buildings is that you rarely need to rip out what you have. Modern IoT kit is designed to sit alongside a legacy building management system, feeding extra data into a cloud platform while the existing controls carry on running the plant. That hybrid route keeps disruption and cost down, which matters when you are weighing this against every other call on a maintenance budget. If you are trying to prioritise building maintenance on a limited budget, a phased rollout of sensors on your highest-risk assets is often a sensible first move.
Reactive versus planned
The strongest argument for sensors is not the technology - it is the cost of failure. An unplanned breakdown means an emergency call-out, premium parts, out-of-hours labour and, in a kitchen or a let building, lost trade or unhappy tenants while things are put right. When a sensor gives you a warning window of a few weeks, that same repair becomes a planned job done quietly at a convenient time, typically at well under half the cost. You move from firefighting to scheduling.
There is a compliance angle too. TR19 Grease, the BESA specification that governs kitchen extract cleaning, already encourages a risk-based approach: heavy-use kitchens running twelve hours a day or more should be cleaned roughly every three months, moderate use around every six months, and light use annually - but always adjusted to real grease accumulation rather than a fixed date. Sensors that track airflow and pressure help you build the evidence for where your system genuinely sits on that scale, so you are neither cleaning too often and wasting money, nor leaving it too long and letting fire risk climb. It turns "we think it is about due" into "the data says now".
What sensors do not do is make the decision for you or perform the work. They flag a trend; a competent person still has to interpret it, verify the condition on site and carry out the clean or repair. Used well, they sharpen your judgement and stretch your budget. Used as a substitute for inspection, they lull you into a false sense of security. The buildings getting real value are the ones treating live data as a prompt to act, not as proof that everything is fine.
Duct cleaning and the law
Nowhere is this clearer than in commercial kitchen ductwork. A grease sensor or an airflow trend can tell you that deposits are building and cleaning is getting close - but TR19 Grease still sets a hard limit of a 200 micron mean deposit across the system, and the only way to prove where you stand is a physical measurement. That is done with a Wet Film Thickness Test or a Deposit Thickness Test, taken at several points along the run. No dashboard reading substitutes for that verified figure, because it is the figure your insurer and a fire risk assessor will want to see.
The legal backdrop has not changed. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for a premises must manage fire risk - and with around seven in ten commercial kitchen fires starting in the extract system, greasy ductwork is a well-known hazard. Insurers increasingly ask for TR19 Grease evidence, and a gap in your cleaning records can complicate a claim. Sensors strengthen that story by showing continuous oversight, but the certificated clean and the test report remain the documents that carry weight. This matters especially in leased premises, where responsibility for ventilation upkeep can sit in unexpected places; it is worth checking for any hidden maintenance liabilities in a building lease before you assume the duct is someone else's problem.
The sensible position, then, is to let IoT sensors do what they are good at - watching, trending and warning - while keeping trained people and formal testing at the centre of your fire safety and hygiene regime. The technology makes maintenance smarter and cheaper; it does not make it optional.
Questions
No. Sensors are excellent early-warning tools - they can flag rising grease loading or falling extract airflow so you clean at the right time. But TR19 Grease sets a hard 200 micron mean deposit limit, and only a physical Wet Film or Deposit Thickness Test can prove where your system stands. The certificated clean and test report remain the documents your insurer and fire risk assessor rely on.
Usually not. Modern IoT sensors are designed to sit alongside a legacy building management system, feeding extra data into a cloud dashboard while your existing controls keep running the plant. This hybrid approach keeps cost and disruption low, and it lets you start small by fitting sensors to your highest-risk assets first, then expanding as budget allows.
They shift you from reactive to planned work. When a sensor gives a few weeks' warning that a fault is developing, you can schedule the repair quietly at a convenient time instead of paying for an emergency call-out, premium parts and out-of-hours labour. Early, planned fixes typically cost well under half of an emergency, and they avoid the lost trade or tenant complaints that come with an unexpected breakdown.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.