Universities are increasingly aware of their environmental performance – both from the perspective of cost, and due to the increasing visibility of performance data in green league tables such as those produced by People and Planet. So those companies able to offer universities specific solutions for reducing lab energy consumption will easily excel in competitive tenders.
So how do you approach a lab-specific air movement strategy?
- the number of air changes necessary to meet the safety requirement.
- the supply air required for cooling/heating the laboratory to a comfortable temperature for occupants.
- the supply air needed to replenish air exhausted by fume hoods.
The room air management system (for example TROX’s EASYLAB system) manages the supply and extract controllers in order that they respond rapidly 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.
This significantly improves energy efficiency, as it prevents unnecessary supply of conditioned air to the space. See Figures 2 and 3.
The energy savings are made possible by offsetting one form of exhaust air against another. By scaling down room exhaust air extraction in line with fume cupboard extraction when sashes are open, the room air management system is able to prevent over-supply and extraction of conditioned air from the space.
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. This would be fixed on a constant volume cupboard, whereas on a variable volume cupboard the minimum air volume could be around 55 l/s when the sash is down. Converting from constant volume to variable volume would therefore save 170 l/s when the sash is in the down position for a single cupboard.
In addition, a range of solutions can prevent fume cupboard sashes being left open unnecessarily, whilst addressing out-of-hours air management can also deliver savings without compromising operational effectiveness or health and safety. The TROX EASYLAB systems has a range of features designed specifically to address energy efficiency in laboratories and are happy to discuss options. In the meantime, here is a checklist which will prove helpful at design stage.
Checklist for Improving University Laboratory Energy Efficiency
- Is Variable Air Volume technology being harnessed to avoid over-supply and over-extraction?
- Could devices incorporating sensors be used to close sashes that have been left open unnecessarily?
- Are air change rates appropriate across the site? Often these are set on a site-wide basis and could be reduced safely in some low risk laboratory areas of the site.
- Could the air change rates be reduced overnight or at the weekend when the laboratories are unoccupied?
- Could occupancy sensing be used on a zone-by-zone basis to link air change rate with demand?
- Could working sash heights for fume cupboards be reduced? Reducing the working sash height from 500mm to 400mm, for example, can achieve a 20% reduction in the air volume at no cost and with negligible impact on working practices.
- Could fan speed be optimised by detecting and analysing damper blade positions?
- Could fume cupboard efficiency be upgraded by retrofitting new control technology to existing cupboards?
- Could local cooling or extraction devices such as ventilated down flow tables, canopy hoods or fume exhaust ‘snorkels’, reduce energy consumption by taking heat away at source?