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BSEE
Effective air management is crucial to create safe, energy efficient and flexible laboratory spaces. So, what design principles should HVAC system designers follow to meet the challenging requirements of today’s laboratories, asks Ian Thomas, product manager – LabControls, at TROX UK
emphasised the urgent need for greater flexibility. To meet the intense demand placed on laboratories, management teams at healthcare sites are seeking ways to increase occupancy levels by enabling multiple scientific disciplines to work safely and effectively alongside one another. The facilities also need to be reconfigured more quickly and easily than in the past, to enable the types of activities carried out in the lab to be adapted in response to changing priorities.
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Even before the pandemic, clinical and research teams in the UK had begun to identify the importance of designing laboratories to facilitate multidisciplinary working. Back in 2018, for example, the imperative for teams from different scientific disciplines to be able to work alongside one another was key to the design of the new Collaborative Teaching Laboratory (CTL) at the University of Birmingham. ‘Collaboration’ held a double meaning for this project. In addition to promoting interdisciplinary engagement across the different departments of the university, the new building was designed, internally, to lower the amount of redundancy present when running multiple single-disciplinary labs. The aim was to create spaces that are utilised for a greater percentage of the time, with the ambition of achieving occupation rates of up to 70%.
To achieve these aims, in the site’s nine purpose-designed laboratory spaces, TROX EASYLAB room air management systems were installed incorporating 88 TROX VAV (Variable Air Volume) units. The TROX EASYLAB systems manage the supply and extract controllers to provide a rapid response to changes in extract volumes by the technical extract (for example fume cupboards) to ensure the correct air flow balance and room pressure at all times in the laboratories. This safeguards health
and safety of site occupants, and also ensures energy efficient operation.
The system has also been specifically designed, however, for collaborative working. In one area, for example, an EASYLAB system, integrated with the site’s BMS, controls the air management of 50 fume cupboards. It divides the laboratory into five zones. Each zone features two supply air VAV units which track the extract air, ensuring the maintenance of correct leakage flows and enabling multiple scientific disciplines to carry out teaching and research safely and simultaneously, whilst achieving the optimum level of environmental and financial performance.
Energy efficiency Increased demand placed on
healthcare laboratory facilities has inevitable financial and
environmental implications for those managing healthcare sites. The energy consumption of laboratories is often more than three or four times that of offices on a square metre basis. This can mean that laboratory buildings are responsible for between 50% and 80% of the total energy-related (non-residential) carbon emissions of research- intensive universities. Government research facilities, hospitals and private sector laboratories are similarly affected.
The higher energy costs and carbon emissions of laboratories are typically associated with the air supply and extraction requirements of fume cupboards. When sashes of fume cupboards are open, the volumes of air required to maintain a safe working environment for personnel increase significantly. For example, a 900mm wide cupboard with a maximum sash height of 500mm and face velocity of 0.5 m/s would extract approximately 225 l/s of conditioned air from the room. By contrast, the minimum air volume for a variable air volume fume cupboard would only be around 55 l/s when the sash is closed, saving 170 l/s of conditioned air, whenever the sash is in the down position. Effective control of fume cupboard air supply and extraction is therefore essential to tackle rising operational costs. Best practice is to install a room air management system capable of fully integrating fume cupboard air supply and extraction with the wider air management systems to prevent wastage. This will make it possible for all input and extract air for the laboratory to be controlled automatically to ensure that the required ventilation strategy and levels of safety are maintained. The supply and extraction of the fume cupboards (or other technical air management devices) is automatically balanced and offset in line with changing requirements, reducing the total supply and extract volumes.
Other energy saving measures
might include introducing devices to close the sashes of fume cupboards automatically when they are not in use, or the installation of local cooling or extraction devices (such as ventilated down flow tables, canopy hoods or fume exhaust ‘snorkels’) which reduce loading on the site’s central air conditioning facilities by taking heat away at source.
Safeguarding laboratory occupants
Increased flexibility also requires careful consideration of air management to ensure safety of building occupants, with particular focus on the filtration requirements determined by containment levels in the different zones of the site. The Quadram Institute building, at the Norwich Research Park, for example, includes Containment Level 2 and 3 Laboratories, as well as being a clinical trials facility and a centre of excellence for endoscopy. The ventilation systems therefore need to enable multiple clinical and research operations to be accommodated in a single building. To manage the containment requirements in different zones, an EASYLAB room air management system installed at the site controls a pressure cascade. Laboratories are controlled at larger negative pressures than the adjacent circulation spaces serving them, to ensure there can be no reversal of airflow under normal operational conditions. The suite also has an automated ventilation sequence that allows ventilation shut down, fumigation and purge of labs in a number of combinations to allow maximum flexibility. This automated ventilation sequence works by switching the EASYLAB between different flow rate set points and pressure set points to achieve the desired ventilation strategy. Technical specialists worked with TROX during the design phase to determine the most appropriate HEPA filter cells and diffusers for the scheme. This resulted in the installation of specific room pressure control capabilities for the Containment Level 3 laboratories, and volume offset tracking controls for the Containment Level 2 spaces.
30 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2021 Read the latest at:
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n recent years the unprecedented pressure placed on hospital laboratories has
FOCUS: MEDICAL AND HEALTHCARE
Upgrading ventilation systems for hospital laboratories
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