Variable volume fume cupboards for Chemistry
A fume cupboard left running 24/7 uses a similar amount of energy to a detached house, but a recently completed project aims to halve this by retrofitting new controls to the fume cupboards.
Fume cupboards are ventilation devices used widely in laboratories to limit exposure to airborne hazardous substances. However, they use a considerable amount of energy, particularly ones that operate at a fixed extract rate and on a continuous basis - as in many of our research areas.
In Chemistry, lab C13 is typical of this type of operation and contains 16 fume cupboards, with annual energy operating costs around £35,000 and carbon emissions around 208 tonnes of carbon dioxide per year.
In order to significantly reduce these costs and the associated carbon emissions, the University has installed variable volume extract systems that adjust the extract rate of the air according to the height of the sash window (this separates the working chamber from the users and was previously varied by the user manually opening or closing the sash). The extract rate can be reduced down to 25% of the existing volume flow rate when the sash is in the lowest position and is achieved by introducing a damper and control system in the extract duct.
To maximise these potential savings an auto sash closing mechanism has been installed, which uses a passive infrared sensor to close the sash when no one is working at the fume cupboard. The sash has to be manually lifted by the user, so it is not opened simply by some walking in front of the fume cupboard.
This system in Chemistry is expected to save £19,300 per year in energy costs and 130 tonnes carbon dioxide for a total project cost of £81,500. This represents a significant reduction in operational energy use and carbon emissions.