- The Arthur Willis Environmental Centre provides facilities to grow plants for research
- Working together, the facility鈥檚 technical manager and EFM trialled adjusting the air handling units鈥 fan speeds, initially to resolve problems with the plant growth conditions in the greenhouse
- Multiple positive outcomes meant that they then reduced fan speeds across the whole greenhouse, reducing their electricity consumption by 22%
Background:
The Arthur Willis Environmental Centre (AWEC), one of the UK鈥檚 largest and most advanced controlled environment facilities, can simulate a wide range of environments to grow and study plants in, from tropical to temperate. Research conducted at AWEC includes crop resilience in our changing climate, and development of new technologies for indoor plant growth.
One of these facilities includes the greenhouse, which is made up of 16 independently-controlled compartments for large scale plant growth experiments. Each of these is the size of a large room, and they can have their temperature and lighting adjusted to simulate different environments. All compartments are fitted with an air handling unit which operates around the clock to serve three functions: to bring in fresh air, to circulate air within the compartment, and to control the temperature.
The Challenge:
Ben Palmer, Controlled Environment Facilities Manager, looks after controlled environments both at AWEC and the Central Annexe. Earlier this year he noticed that the powerful air currents from the air handling units were damaging some of the ceiling blinds, which are there to minimise light pollution from the greenhouse. To mitigate this, baffles were installed to redirect the air away from the blinds. However greenhouse users then raised concerns that the turbulent air might be affecting plant growth, and in turn, their research. Seeking another solution, Ben contacted the Building Management System (BMS) team in EFM. This team has control of various systems including heating and ventilation across campus.
Speaking to the BMS team, Ben learned that the fan speeds of air handling units were in fact adjustable. Rather than being fixed 鈥榦n鈥 or 鈥榦ff鈥, they had been set to run at 80% of full speed during the day and at 60% at night, although it was not clear why these values had been chosen.
Trialling a New Approach:
James Richardson from the BMS team supported Ben Palmer in trialling reduced fan speeds in two empty compartments within the greenhouse. This was required to ensure that the facility could still meet the needs of the research by providing enough temperature control with the fans running at slower speeds, particularly on hotter days. Together, Ben and James monitored the internal conditions over five days in June to see how they varied from their setpoints, with the fans reduced from 80% to 60% of maximum speed during the day and from 60% to 50% at night.
They found that the internal temperatures were unaffected by the reduction in fan speeds, even with external temperatures reaching 30掳C on two days of the trial period. As a result, they were able to apply the new fan settings to the air handling units serving all 16 compartments of the greenhouse, confident that there would be no negative impact on the research happening within them. In fact, running the fans at a reduced speed has mitigated the issue initially raised by the researchers: that turbulent air might be damaging growing plants.
The Impact:
This adjustment will save about 37,800 kWh of electricity per year - the same amount of electricity that 14 would use in that time - which is a 22% reduction from what the fans were using before. At current prices, this reduces our electricity bill by more than 拢9,000 annually.
This case study highlights several key takeaways. Firstly, small adjustments to the way in which electrical equipment is run can result in substantial savings - this is particularly true for equipment that is operational 24/7 or over a large region of space. Secondly, it can often be technicians or facility managers who are best placed to identify these sorts of adjustments, as such adjustments may require detailed knowledge of what the equipment is being used for, or be on a scale too small to be on EFM鈥檚 radar. Thirdly, it is worth questioning why things have been set up in the way that they have, and whether or not this exceeds the need; in this case, there was no clear justification as to why the fan speeds had been set to what they were.
Beyond the financial and operational benefits, this case study underscores a big win for energy efficiency and sustainability. The reduction in electricity use demonstrates that adjustments in equipment operation can promote more sustainable research environments, and helps us move towards decarbonising our energy supply as we approach our target of net zero on campus.
Ben Palmer, Controlled Environment Facilities Manager, said: 鈥淭his energy saving was actually a knock on effect from trying to improve the growing conditions for some of our facility users. I was pleasantly surprised at how well the greenhouse still managed to maintain its setpoint, even with the high ambient temperatures outside.
鈥淚 think this particular case study highlights that support staff on the ground are well placed to identify subtle energy savings in their own work areas - small changes can make a big difference.鈥
Louis Garnham
Environmental Projects Co-ordinator
Estates and Facilities Management