TL;DR:<\/strong><\/p>\n Visit Delta First<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n HTM 03-01 is published in two parts, and the 2021 edition supersedes the 2007 version that many estates teams still reference from memory. Knowing which part applies to which task saves time when briefing contractors and avoids the common mistake of quoting design guidance during an operational dispute, or vice versa.<\/p>\n Part A deals with everything that happens before a system goes live: specification, plant selection, ductwork design, installation standards and acceptance testing. It sets the benchmarks a new air handling unit (AHU) or isolation suite must meet before handover, and it is the document your mechanical contractor should be working from during a refurbishment or new build.<\/p>\n Part B takes over once the system is operational. It covers routine inspection, planned maintenance, logbook requirements and the annual verification regime that confirms a system still performs as designed. For an estates manager running an existing hospital, care facility or diagnostic centre, Part B is the document you will open most often.<\/p>\n HTM 03-01 applies in several distinct situations:<\/p>\n HTM 03-01 does not sit in isolation. It works alongside HTM 04-01 on water safety where plant interacts with domestic services, and it is supplemented for isolation facilities by the HBN 04-01 supplement on special ventilated isolation facilities, which sets out pressure regimes and filtration detail that HTM 03-01 references but does not fully repeat. Building Regulations Part F and Part L still apply to the fabric and energy performance of the building envelope, so a compliant ventilation system also needs to sit within a compliant building shell. Estates teams managing a mixed estate, some wards decades old, some newly built, often find the practical answer is to treat Part A as the target and Part B as the ongoing discipline that keeps you there.<\/p>\n Verification visits and document audits tend to focus on a handful of numbers. Knowing what they should say, and why, makes it far easier to spot a system that has drifted out of compliance before it becomes a clinical risk.<\/p>\n Isolation suites are the area where pressure regime failures cause the most harm. The HBN 04-01 supplement sets out the logic clearly: an infectious isolation bedroom runs negative to the corridor, its lobby runs positive relative to both the bedroom and the corridor. The pressure differentials must be tight enough to control airflow direction without making doors difficult to operate safely. This arrangement, often referred to by its abbreviation PPVL (positive-pressure ventilated lobby), only works if door seals, dampers and fan speeds are all still within their commissioned tolerances. A door that sticks or swings freely is often the first visible sign that pressures have drifted.<\/p>\n Filtration guidance has moved on considerably from older classifications. Current recommendations point towards ISO ePM10 and ePM1 grades for general supply air, with the HBN 04-01 supplement specifying that supply terminals serving isolation facilities should accept an EPA E12 filter, and that supply pre-filters and final filters together should achieve the SUP2 classification under BS EN 16798-3. Specifying AHUs with housings that can accept EPA E12 or HEPA-grade filtration, even where current use does not demand it, gives estates teams headroom to upgrade without replacing plant, which matters given how long AHUs typically stay in service.<\/p>\n A handful of items are worth checking on every inspection:<\/p>\n Fans can account for around 40% of a ventilation system\u2019s total electricity use, which is why HTM 03-01 Part A favours electronically commutated fans over older belt-driven designs.<\/strong> That single specification choice affects running cost for the entire operational life of the plant, so it is worth insisting on at tender stage rather than treating it as an optional extra.<\/p>\n Where no more specific guidance applies to a space, a minimum fresh air rate of 10 litres per second per person is the baseline many estates teams fall back on, reflecting the general ventilation hierarchy HTM 03-01 sets out: dilute first, filter and direct airflow second, and rely on supplementary measures such as portable air cleaning only as a last resort. That hierarchy matters when a ward raises concerns about air quality and the instinctive response is to reach for a portable unit rather than check whether the fixed system is even performing to its commissioned rate.<\/p>\n Part B sets out a two-tier inspection regime for critical healthcare ventilation, and the two tiers are frequently confused with each other, which is one of the more common findings during compliance audits.<\/p>\n The first tier is a quarterly simple visual inspection. This is a walk-round check: confirming fans are running, filters are not visibly clogged, pressure gauges read within expected ranges and there is no obvious damage to ductwork or terminals. It does not require calibrated instrumentation and can usually be carried out by a competent in-house technician.<\/p>\n The second tier is the annual detailed performance verification, and it is a different exercise entirely. This requires calibrated instruments to measure air change rates, room pressure differentials and filter pressure drop against the original commissioning benchmarks, or against a re-established baseline where the original data cannot be found. Treating a quarterly walk-round as if it satisfies the annual verification requirement is one of the most frequent gaps found on audit, and it leaves a trust unable to demonstrate that the system still performs as designed.<\/p>\n A working logbook and user manual should include, at minimum:<\/p>\n The AE(V) exists to give an independent, technically qualified view of whether a trust\u2019s ventilation systems are being designed, commissioned and verified correctly. Procurement notices for these roles, of the kind published through Contracts Finder<\/a>, confirm that appointing an AE(V) is standard practice across NHS trusts, not an optional extra reserved for the largest estates. Independence matters here: an AE(V) who also holds the maintenance contract for the same plant creates a conflict of interest that auditors will flag, so contracts should specify functional separation between the two roles.<\/p>\n Permit to work systems matter as much for ventilation as for any other live building service. Isolating an AHU or extract fan for filter change should require a signed permit, confirmation that sealed access and cleaning hatches have been checked for integrity, and use of a safe-change housing for any filter handling potentially contaminated air. Each of these steps should leave a paper trail that lands back in the logbook.<\/p>\n Pro Tip:<\/strong> Keep quarterly visual inspection records and annual verification reports in physically separate log sections. It makes the distinction obvious to anyone auditing the file, including your own team six months later.<\/em><\/p>\n Local exhaust ventilation (LEV) is a distinct category from general HTM 03-01 ventilation, and it carries its own statutory examination regime under the Control of Substances Hazardous to Health Regulations. LEV applies wherever a process, such as a pathology fume cupboard, a pharmacy compounding hood or a workshop extraction point, generates an airborne hazard that needs to be captured at source rather than diluted by general ventilation.<\/p>\n HSE guidance INDG408<\/a> sets out the core requirement: LEV must be properly designed, commissioned, used and maintained, and it must undergo a thorough examination and test (TExT) carried out by a competent person. The statutory maximum interval between tests is 14 months, and HSE guidance, reinforced in HSG258, treats an annual cycle as the practical norm. This is a legal duty under COSHH, separate from the HTM 03-01 annual verification schedule, and the two are easy to conflate when a single contractor is managing both.<\/p>\n The TExT report itself needs to cover specific ground:<\/p>\n Design and commissioning for LEV carries its own detail that differs from general HTM ventilation: correct hood selection for the hazard and task, permanently fitted or accessible test points for instrumentation, and a user manual that tells operators how to recognise a fault, such as an unusual noise or a visible drop in capture performance. The most common compliance mistake is treating LEV as part of the general ventilation PPM round rather than as a standalone statutory duty with its own certificate, its own competent tester and its own 14-month clock. Keeping LEV TExT certificates in a separate, clearly labelled file from HTM verification reports avoids that confusion at the next audit.<\/p>\n Annual verification is only meaningful when it is measured against something. That something is the commissioning baseline, and a surprising number of estates teams manage systems where that baseline has been lost, was never properly recorded, or belonged to a configuration that has since changed.<\/p>\n A proper commissioning record should include:<\/p>\n Re-commissioning becomes necessary in a few recurring situations: when no reliable baseline exists at all, when a room\u2019s clinical use has changed (a general ward bay becoming a negative-pressure isolation room, for example), or when plant has been replaced or substantially altered without a fresh acceptance test. Waiting until the annual verification fails before addressing this is the wrong order of operations. It is far cheaper to re-commission proactively and enter the annual cycle with a defensible number to test against.<\/p>\n The measurements that matter most for ongoing verification are air change rate, room-to-room pressure differential, and filter pressure drop, each compared against the commissioned or re-established baseline rather than against a generic industry figure. Reporting should be traceable: raw readings, the date and time they were taken, the instrument reference and the technician\u2019s name, not just a pass or fail summary.<\/p>\n When briefing a contractor for commissioning or verification work, a procurement checklist should ask for calibration records for every instrument to be used, confirmation of AE(V) witness where required, a defined corrective action process for any reading outside tolerance, and an agreed reporting timetable that gets the final report into your logbook within a set number of working days.<\/p>\n Pro Tip:<\/strong> Ask any contractor quoting for verification work to state upfront how they will establish a baseline if none exists. A vague answer here is the clearest sign of a rushed job to come.<\/em><\/p>\n Most estates teams do not need a full audit to know roughly where they stand. A short triage exercise surfaces the priority gaps quickly, and it gives you a defensible starting point if a compliance question comes from above before a full review is complete.<\/p>\n Start with the basics:<\/p>\n Where remedial work cannot happen immediately, interim controls can reduce risk while it is arranged. Temporary HEPA filtration units are sometimes used as a stopgap in affected spaces, but NHS guidance on HEPA filter devices in healthcare spaces is clear that these are adjuncts, not a substitute for a properly functioning fixed system, and their use should follow that guidance rather than being treated as a fix. Readers comparing supplementary units for interim use can also refer to independent buying guidance such as Simco Direct\u2019s overview of commercial air purifiers when assessing options. Operational changes, such as restricting a room\u2019s use until pressure regimes are confirmed, or adjusting patient flow to avoid a suspect isolation bay, often do more to manage risk in the short term than any portable device.<\/p>\n Record retention and audit readiness come down to one question: could you hand your logbook to an inspector tomorrow and account for every system\u2019s current status? The table below sets out how the main compliance elements should be classified for budgeting purposes.<\/p>\n\n
\nWhat HTM 03-01 covers across parts A and B<\/h2>\n
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Filtration, pressure regimes and minimum airflow benchmarks<\/h2>\n
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Inspection cadence, logbooks, permits and the AE(V) role<\/h2>\n
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LEV and COSHH: the statutory regime that runs alongside HTM checks<\/h2>\n
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Commissioning, re-commissioning and setting a defensible baseline<\/h2>\n
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A practical checklist for triaging HTM 03-01 compliance now<\/h2>\n
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