For estates teams, infection prevention leads and M&E consultants specifying healthcare HVAC, understanding how air change rates, filtration and pressure cascades interact is core to meeting HTM 03-01, the NHS's specialised ventilation standard, and to protecting the patients and staff inside the building.
Here we break down exactly how HVAC systems influence infection risk, why the entrance is as much a part of the system as the ductwork, and what a compliant, well-specified healthcare ventilation strategy actually looks like in practice.
What Role Does Ventilation Play in Hospital Infection Control?
Airborne pathogens travel wherever air travels. In a healthcare building, that makes ventilation design a frontline infection control measure, not a comfort feature. Three mechanisms do most of the work:
- Air change rates (ACH) — how frequently the air volume in a room is fully replaced, diluting the concentration of any airborne contaminant present
- Filtration grade — determines what's physically removed from supply air before it reaches occupied space; HTM 03-01 specifies filtration standards by room type and risk category
- Pressure cascades — a deliberately engineered pressure difference between adjoining spaces, so air flows out of clean zones (theatres, isolation rooms) and into higher-risk zones, rather than the reverse
A 2025 literature synthesis of post-COVID-19 hospital ventilation research (MDPI, Ventilation and Infection Control in Healthcare Facilities: A Post-COVID-19 Literature Synthesis) reaffirmed the critical role ventilation plays in airborne infection control, while identifying evidence gaps and highlighting which design, maintenance and operational advances are best supported by research to date.
How Does HTM 03-01 Regulate Healthcare Ventilation Design?
HTM 03-01 splits responsibility into two parts, and both matter for infection control:
- Part A covers the concept, design, specification, installation and acceptance testing of new ventilation systems and major refurbishments
- Part B covers the management, operation, maintenance and routine testing of existing systems, with no exemption based on the age of the installation
That second point is easy to miss. A ventilation system installed long before the current HTM 03-01 was published in June 2021 is still expected to be actively managed against it, not grandfathered out of scope.
Alongside HTM 03-01, ASHRAE Standard 170 sets ventilation rate requirements for healthcare facilities internationally, and the CDC provides specific guidance on ventilation measures to reduce airborne transmission of pathogens like tuberculosis and COVID-19; a useful cross-reference for teams benchmarking UK compliance against wider clinical ventilation science.
Where Do Entrances Fit Into Infection Control Strategy?
It's tempting to think of infection control purely as an air-handling-unit problem: filters, ducts, fan redundancy etc. But every time an external door opens, it's a direct route for outdoor air, and whatever it's carrying, straight into a space where pressure, temperature and filtration have been carefully engineered.
This is where air curtains earn a genuine place in a healthcare ventilation specification. A correctly specified unit creates an air seal across the doorway, reducing air exchange between inside and outside without slowing things down.
The infection-control case for this isn't theoretical. A peer-reviewed numerical study (Building Simulation, Springer) of air curtains fitted to hospital consulting desks found the average mass fraction of exhaled pollutants decreased by 70–90% in the consulting ward when the air curtain was in use. The same research found supply air velocity and angle both critically affect that cut-off performance.
Biddle's SR and DoorFlow2 ranges are designed specifically for this kind of high-traffic, infection-sensitive doorway where an air seal has to hold up against constant use, not just occasional opening.
What Does Good Healthcare Ventilation Specification Look Like?
A ventilation strategy that actually protects against airborne infection risk needs every element assessed against the same standard, not just the parts that are easiest to check:
- Air change rates matched to room risk category, per HTM 03-01 Part A guidance for new installations and refurbishments
- Filtration grade appropriate to the space — theatres and isolation rooms need a materially different specification to general wards
- Pressure cascades engineered and verified, not assumed — negative pressure for isolation, positive for theatres
- Doorway air seals at every external and high-traffic entrance, sized and angled for the specific opening frequency and space they serve
- Ongoing Part B management — testing, validation and maintenance scheduled regardless of installation age
Specify Healthcare Ventilation With Infection Control Built In
Biddle's Healthcare Solutions range is designed to support in a number of functions within the sector. Read our Healthcare Solutions brochure for full product specifications, or get in touch with Biddle's healthcare team to discuss ventilation strategy for an NHS or private healthcare project.