FEATURE HVAC SYSTEMS
Demand-based ventilation reduces HVAC energy costs
The University of Cambridge’s Hutchison/MRC Research Centre was faced with the unsettling prospect of reducing life-saving cancer research to pay utility bills. After implementing a unique airside solution that allows ventilation to vary based on laboratory conditions, the centre reduced total natural gas costs by approximately 41 percent in the first year, and by 54 percent in year two. The total electricity bill was reduced by 9 percent. Here’s more on how the new system from Aircuity helped cut cost and emissions
J
ust a few years ago, Brian Richardson, research manager for the
Hutchison/MRC Research Centre, was talking to his long-term airflow control system vendor Critical Airflow Europe about energy use at the cancer research facility. He mentioned that he was looking at having to cut the facility’s research budget to pay for the lab’s utility bills. Gas and electricity bills were extremely high – and growing at a rapid rate. Full air conditioning was required at all
times to keep the laboratories operating properly. This meant that ventilation systems had to be operating at the same rate day and night – whether occupied or unoccupied. The building was also running at higher than normal air change rates, due in part to flaws in the building’s original design. The building engineer was aware that the original design flaws in heating and ventilation required a retrofit of standalone fan coil units in offices and equipment rooms to supplement heating and cooling. Chris Mulholland, operations director for
Critical Airflow Europe, told Richardson that he might have a solution to retrofit the building to provide energy savings of as much as 50 percent. The new solution would modify the centre’s traditional variable air volume (VAV) control in lab spaces with the demand-based Aircuity system, which allows the ventilation to vary based on conditions in each laboratory. With numerous installations at U.S. university laboratories, the Aircuity system proposed for the Hutchison/MRC Research Centre would be the first in the United Kingdom. The Aircuity airside efficiency platform
optimises air change rates based on comprehensive indoor environmental data. It continuously collects an array of building indoor environmental data. Air samples are gathered from individual spaces and at the air handler level and routed through the network to the Sensor Suite for analysis.
14 WINTER 2017 | ENERGY MANAGEMENT
energy costs by 40-60 percent in laboratory spaces. The system payback was less than two years. In addition, the system reduced carbon emissions by 422 metric tonnes per year (about 464 US tons per year). According to Mulholland, research centre
manager Brian Richardson is an extremely proactive system user, evaluating airflows and managing the energy saving information online. He can also diagnose how the VAV units in the building are performing by checking the Aircuity information online. The system can be applied as a retrofit or
The sampled data is then transmitted
to the web-based platform for archiving and reporting. A signal is also sent to the facility’s building management system (BMS) to adjust the ventilation levels based on current conditions, which provides energy savings while improving indoor environmental quality. Critical Airflow proposed to reduce the air
changes per hour (ACH) from the existing rate of 24 ACH for both occupied and unoccupied periods to a minimum air change rate of 4 ACH during the day and 2 ACH during night periods. Figure 1 shows the system basics.
TROUBLE FREE INSTALLATION AND INSTANT RESULTS The capital cost of the project was £94,000 (about $118,000), which was shared between the MRC and the University of Cambridge. The day the system was switched on, the baseline air flow went from 1000 litres per second (L/S) down to 200 L/S. In the first year, the system reduced total gas costs by approximately 41 percent, and the total electricity bill by 9 percent – a combined saving of around £67,000 (about $85,000). In the second year, total gas costs were down by 54 percent. Results showed that the system can reduce HVAC
Figure 1:
Aircuity system allows ventilation to vary based on conditions in each laboratory
as a new build and is applicable to a variety of University buildings, including lecture theatres, labs, and libraries. Two Aircuity projects are currently in the pipeline, one at the new Capella lab and the other in the Chemistry Department extension. Installing the Aircuity system helped
building managers who were caught in a situation of using the precious research science budget to pay their gas bill. The year on year savings they achieved has ensured the most efficient use of their hard earned resources, protecting the science budget rather than simply paying the utility company. “Installation of Aircuity has provided
significant and varied benefits to our research centre,” concludes Richardson. “We achieved our main goals of improving the laboratory environment for our occupants, reducing the environmental impact of the research centre, and, crucially, reducing our expenditure on utility costs. Without this installation, we would have been in the unenviable and inevitable situation of having to reduce direct research budgets to pay our gas bill. But now, with such impressive financial benefits the science budget is protected, with a direct positive impact on cancer research.”
Aircuity
www.aircuity.com e:
customersupport@aircuity.com
/ ENERGYMANAGEMENT
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