by Roy Jones, Technical Director @ Gilberts Blackpool
Creation, refurbishment and upgrading of healthcare facilities is facing interesting times. The Government has ramped up plans to build new hospitals and now announced additional funding for operating theatres, to increase their number and capacity. At almost the same time, the NHS has published new guidance on ventilation for healthcare premises with two main purposes: to reduce the carbon footprint of the healthcare estate and improve the health of patients and staff alike.
With regard to the carbon footprint, healthcare provision represents more than 5% of the UK’s greenhouse gases. Thus, the new Health Technical Memorandum 03-01 requires the default ventilation principle to be natural ventilation, with mechanical ventilation as a last resort. It has also updated guidance on the provision and selection of filters, to address indoor air quality (3).
Irrespective of the proven benefits of fresh air on our health & wellbeing, it goes without saying that good indoor air quality is critical in hospitals: 10% of patients contract an infection whilst in hospital(1), and up to 25% of infections as a result of surgical interventions come from an airborne route(2).
An over-riding principle of the new guidance is that energy consumption of ventilation systems should be minimised by specifying solutions with the lowest lifecycle environmental cost. The basic objective of energy-saving strategies is to provide the required ventilation service using the minimum energy. To this end, Health Technical Memorandum 03-01 recommends “switching a system “off” when not required to be the most energy-efficient policy. If the system is needed to maintain a minimum background condition, reducing its output by “setting back” to the minimum necessary to achieve and maintain the desired condition is the next best option”.
HTM03-01 also recognises that whilst natvent may be the preferred option, depending on the environment- which are many and varied within a healthcare estate- it may not always be the most appropriate. The number of air changes also varies with the activity in an area: in areas requiring a highly sterile environment, such as operating theatres, as many as 22ac (air changes)/hour is now the standard.
One of those highly sterile areas is the operating theatre. HTM 03-01 has updated guidance on ventilation in general operating theatres.
Now, HTM 03-01 recommends the use of either of two means of ventilation, particularly over the operating table: laminar flow or radial convergence, providing at least 22 ac (air changes)/hour at a velocity of between 0.2 and 0.3m/3. Horizontal flow distribution should not be used in new installations and only if space constraints force its inclusion in refurbishments/upgrades.
At one of the UK’s leading independent test facilities- actually that @ Gilberts Blackpool- in-depth research has been carried out to validate the most effective option. Both ventilation principles were tested via Computational Fluid Dynamics (CFD) modelling and real-time testing within the test facility.
The research(3) found that the best way to ensure optimal removal of potential airborne pollutants from around the patient on the table was laminar flow. This delivered a continuous supply of filtered air in one direction downwards, thus washing over the patient area without risk of any contaminants from the surrounding area. The radial convergence (with diffusers) option allowed potential for the air be redirected back over the patient increasing the potential risk of contamination.
The location of the ventilation in relation to the patient/operating table is vital to its effectiveness. In order to ensure correct air distribution ideally the terminals should be co-ordinated with lighting and equipment positions at the design stage to ensure no clashes occur to disrupt the air distribution. Filters should be fitted to purify the incoming air(4) and design should take account of the need to replace filters during the lifespan of the theatre.
HTM 03-01 is guidance and is crucial, if we are to successfully use this to ensure ventilation in healthcare is efficient and effective. We would always advise use of specialists in the supply chain, who have a proven track record and the capability to step up and work with you to deliver the best healthcare project.