Fume Cupboard Flow – Saving Energy in Laboratories
Martin Farley – Research Efficiency Manager, KCL
Common within many laboratories are fume cupboards, which are large pieces of equipment which safely extract air within a contained small area to ensure worker safety. King’s College London (KCL) is no different in that it contains several hundred of them, albeit only 30 or so are directly under KCL management. This is due to the fact that the majority of KCL’s research spaces exist either within the Trust, or within Bouygues operated spaces (under PFI contracts). Fume cupboards are notorious for consuming large amounts of energy, and can easily consume more than the average UK household uses. That said there are many ways in which this may be mitigated to achieve energy savings, and thus significantly reduce the impact of KCL’s laboratories on the environment. With this in mind, KCL’s Energy team managed a project to achieve exactly that, and targeted the worst offenders under KCL management.
Fume cupboard within KCL managed buildings were surveyed for flow rates, including the Hodgkin building, James Black Centre, the Rayne Institute, and the newly built Wohl. There was a focus on flow rates in particular as it is common for them to creep up over time. Increased flow means more air is exhausted, which the college has likely heated or cooled, resulting in waste energy. As such, surveying existing fume cupboards for excessive flow rates helped highlight which were particularly wasteful. Furthermore, all fume cupboards surveyed were ‘fixed-flow’ or in other words typically on 24/7 with a constant volume of extract. All fume cupboards surveyed were considered for conversion to variable air-volume (VAV), where flow rates are automatically reduced when sashes are lowered and not in use, resulting in significant energy savings. Conversion to VAV is only appropriate for fume cupboards in heavy use and in particular settings, and the surveys revealed only one fume cupboard was appropriate for this within the Rayne building located at Denmark Hill.
12 fume cupboards across King’s were selected for reduction in flow rates, while one designated for conversion to VAV from fixed flow. Flow rates discovered during the survey varied from 40-70% higher than necessary. Coupled with savings due to a heavily-used fume cupboard being converted to VAV, the project had an estimated payback of only 2.5 years. Pictured here is laboratory manager Amanda Wilson of the Rayne, who manages the fume cupboard which was converted to VAV. This conversion was particularly prudent as the Rayne building is undergoing significant ventilation upgrades, and thus an existing VAV systems savings will be compounded. A review of the fume cupboards showed that flow rates had remained low in the year since project completion, putting savings at an estimated £3,800 per year.