Modern Building Services

FEATURE VERTICAL FOCUS: RETAIL, EDUCATION AND LEISURE MODERN BUILDING SERVICES JUNE 2022 27 4. Preventing wastage with fume cupboard best practice It is very common for sashes to be left open unnecessarily when individuals are away from the fume cupboards. Changes in work practices, or visual reminders in the laboratory can reduce energy consumption by reminding lab occupants to close sashes when they are busy elsewhere. In addition, PIR (passive infrared) sensors can be installed to identify times when fume cupboards are unattended. After a set time a visual or audible alarm is triggered to indicate that the sash has been left up. An auto sash closer can then work in conjunction with the sensor to close the sash automatically, preventing unnecessary extraction of conditioned air. Step 5. Reviewing fume cupboard controls As part of your review of fume cupboard efficiency, check whether there is resident technology that is currently unused. It is quite common for specific control features to be left unconfigured at the time of installation of the fume cupboard. Contact the manufacturer, or a lab air management specialist, to investigate whether additional energy-saving features on existing hardware can be brought into operation. It might also be possible to retrofit advanced control to existing lab hardware, to maximise return on capital investment whilst providing new energy efficiency and safety capabilities. Step 6. Integrating fume cupboards with a room air management system The most significant energy reductions can be achieved by integrating fume cupboard air supply and extraction with the wider air management systems to prevent wastage. Installing a room air management system (such as our EASYLAB system) makes 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. Supply and extraction of the fume cupboards (or other technical air management devices) are automatically balanced and offset in line with changing requirements, reducing the total supply and extract volumes. For example, if the fume cupboards are open and extracting air, there is not the same requirement for the room system to carry out this process. By scaling down room exhaust air extraction in line with fume cupboard extraction, the room air management system is able to prevent wastage associated with over-supply of conditioned air, improving energy efficiency significantly. Step 7. Removing heat at source Another way to reduce demand on the site-wide cooling and ventilation system is to install equipment such as ventilated downflow tables, canopy hoods or fume exhaust ‘snorkels’. These can reduce energy consumption by taking away heat at the source, and are particularly helpful where cooling demand relates to intensive usage of IT equipment on laboratory benches. Step 8. Tackle energy consumption out-of-hours Typical office space would require four air changes per hour. In the laboratory environment, due to the nature of the activities and substances present in the space, the number of air changes is typically set considerably higher to err on the side of caution. One energy-saving opportunity is to set the BMS (Building Management System) to reduce air change rates overnight or at the weekend when the laboratories are unoccupied, and the requirement for air changes is therefore lower. Local overrides can be used to ensure that, if personnel should be working out of usual work hours, the air changes can be re-established at times when the BMS has put the building into reduced mode. Step 9. Check Zoning As part of any project to address laboratory energy consumption, double-check the settings of different zones to ensure that the air change rates suit the activities carried out in each space. Step 10. Energy efficiency across the site as a whole In addition to addressing the energy efficiency of the laboratory spaces, give careful consideration to the operation of the centralised air management system. One approach with significant energy-saving potential is to harness the opportunities presented by the latest generation of VAV technology to control fan speed using the positioning of the damper blade (rather than via duct pressure measurement). Installations employing this approach to date indicate that fan energy consumption can be reduced by around 45%. A number of our standard products and solutions have the digital control capability for this approach already resident, facilitating fan speed optimisation without the need for bespoke BMS programming. 1 Peter James and Lisa Hopkinson, ‘Carbon, Energy and Environmental Issues Affecting Laboratories in Higher Education - A Supplement to the HEEPI Report on General Regulations and Schemes on theTopic’, August 2011. 2 Installed at the University of Birmingham is our EASYLAB room air management system incorporating 88 VAV units. The fume cupboards are fitted with our EASYLAB TVLK-type fume cupboard controllers. More information can be found at www.troxuk.co.uk