HVAC SYSTEMS
improved indoor air quality, resiliency, and energy efficiency, to the healthcare setting, but perhaps not every change should be taken to the letter. The HTM is, after all, open to derogations from the guidance, as long as these provide an equivalent degree of safety. There are value engineering options available that would deliver identical value and results without inflating the cost to the design. Take the new recommendation for the casing construction to be Thermal Transmittance T2 and Thermal Bridging TB2 for example.
T2/TB2
Requirements for a T2/TB2 casing construction are now an integral part of HTM 03-01, with the aim of combating condensation and heat loss through the casing of the air-handler. Taken at face value, it would be fair to assume that all healthcare AHUs now need to be classified as T2/TB2, under the BS EN 1887 standard. However, casings designed to achieve a T2/TB2 classification are expensive, and often make use of plastics to provide thermal breaks between the inside and the outside of the casing. Furthermore, their use is not always warranted unless certain risk factors are present. They are therefore not always the most cost-effective, environmentally-friendly, or appropriate solution. As a supplier of bespoke air- handling products, T2/TB2 casings included, we could gloss over this, but we know that this solution is not appropriate for all situations, and can often add significant cost to the project, while providing little added value.
T2/TB2 is essential in areas that might be subject to high relative humidity and extreme temperatures, where the temperature differential between the outside and the inside of the unit is sufficient to create concerns over the formation of condensation on the surface of the casing. However, most healthcare AHUs will be housed in a ventilated plant room in sheltered conditions, where the ambient temperature is controlled, and with these units often not cooling to very low temperatures (<10˚C), a thermal classification T2/TB2 would really add no value, other than eating substantially into the budget.
Correct interpretation This is just one example of why interpretation and knowledge are key. It is obvious to us that some revisions need to be applied across the board, whereas others need careful interpretation. Some affect installation, while others impact the lifespan of the unit. They are all important to improving IAQ, reducing waste, and helping the NHS achieve its efficiency goals and meeting required standards, but all need applying to different degrees depending on the environmental setting.
40 Health Estate Journal September 2021 In summary
To summarise, the changes to air-handling unit design introduced with the publication of the revised HTM 03-01 (2021) shouldn’t come as a surprise, as they mostly address topics which have long been in the agenda, such as new legislation and standards, system resiliency, efficiency, sustainability, and the improvement of IAQ. We can say, in brief, that the following major areas have been addressed in this revision: n A ‘refresh’ of existing standards and legislation, including the EcoDesign Directive for Energy-Related Products (EU 1253/2014), and updated filtration standard, ISO 16890.
n Selection of appropriate manufacturing materials, with a focus on avoiding corrosion, growth of microorganisms, and unwanted condensation.
n Implementation of energy-efficient solutions for air movement, heat recovery, and controls, covering newer technologies such EC fan walls, and the overhaul of outdated, inefficient requirements, such as the use of droplet eliminators and fan mesh guards. n New requirements and
recommendations to improve system resiliency, such as the use of fan walls and appropriate access and maintenance facilities.
n Updated installation, validation, commissioning, maintenance, and service requirements and guidance.
Informed interpretation of these changes will make all the difference to not only meeting the required standard for healthcare ventilation systems, but also meeting budget requirements by supplying systems that are cost-effective and appropriate for their environment. I absolutely recommend engaging with experienced healthcare ventilation suppliers for more detailed information on how specific products can comply with the HTM 03-01 (2021).
Demand for healthcare infrastructure is high following the 2020 government announcement that 40 new hospitals will be built by 2030 as part of a package worth £3.7 billion, delivering on the commitment to improve the UK healthcare infrastructure in the face of the COVID-19 pandemic and Brexit.
Open to discussion
Anyone familiar with the HTMs knows that while some of the guidelines are straightforward and easy to understand, most of the guidance can be vague and somewhat open to interpretation. The new version of the HTM 03-01 still contains many potential ‘grey areas’, and its execution should therefore be discussed carefully and objectively. This is the main reason that we decided to come up with a CPD on the topic, which will hopefully allow
us to both inform and open a dialogue with professionals in our industry. The Barkell HTM 03-01 CPD is available, free of charge, to any industry professional who might benefit from this information.
References 1 HTM 03-01, Specialised ventilation for healthcare buildings. NHSE/I, 22 June 2021 [
https://tinyurl.com/zv56a3px].
2 Delivering a ‘Net Zero’ National Health Service. NHSE/I, 1October 2020 [
https://tinyurl.com/kecjm28c].
3 The Clean Air Hospital Framework. Global action Plan, 5 March 2019 [
https://tinyurl.com/btza9tz4].
4 Toxic air at the doors of the NHS. British Lung Foundation, October 2018 [
https://tinyurl.com/6369x5kd].
5 Can damp and mould affect my health? The NHS, 8 August 2021 [
https://tinyurl.com/5ftc3eb6].
6 Aspergillosis advice, The NHS [
https://www.nhs.uk/conditions/ aspergillosis].
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Bruno Guedes
Bruno Guedes is the head of Technical Solutions at Barkell, a leading UK manufacturer of bespoke air-handling units. His role leverages his own hands-on knowledge, as well as Barkell’s extensive 40-year experience in the design and delivery of air-handling systems, ‘to provide tailored solutions to the most technically demanding sectors in the UK construction industry’. He holds a Bachelor’s degree in Renewable Energy Engineering, and, having begun his career with an air-handling unit manufacturer in Portugal, has been with Barkell since 2015, holding increasingly senior positions of technical responsibility. He has overseen an AHU design software implementation project, the introduction of the EcoDesign directive, Building Information Modelling, and the development of multiple ventilation products, during his six years with the business.
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