The following blog post was originally submitted by Aircuity and published in the April edition of Buildings Maintenace & Management of Southern California. This article discusses how universities [the University of Cambridge] can reduce HVAC energy costs by more than half when using Aircuity’s demand control ventilation technology.
University Uses Demand-Based Ventilation to Reduce HVAC Energy Costs By More Than Half
In the face of growing 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, Hutchison/MRC 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. The new system, which had a payback of fewer than 2 years, also helped reduce carbon emissions. What’s more, the savings have continued to grow year over year in the 4 years since the system has been in operation.
UNIVERSITY LAB SEEKING ENERGY REDUCTIONS TO ELIMINATE RESEARCH BUDGET CUTS
A leading site for basic and translational cancer research, the Hutchison/MRC Research Centre was built in 2001. It houses about 160 research scientists and support staff from the MRC Cancer Unit and Department of Oncology, University of Cambridge, working in 11 laboratory spaces over three floors. The center has about 1,115 square meters (12,000 square feet) of lab space, plus one floor for support services and one plant room floor.
Just a few years ago, Brian Richardson, research center 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. He had spent years trying to tweak and improve the system to make the best of the situation.
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 center’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 optimizes 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. 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.
Richardson initially questioned whether the retrofit could actually achieve such a high level of energy savings. He agreed to entertain the notion because Critical Airflow had been supplying laboratory control, critical airflow systems and building management system services to MRC for years. The capital cost of the project was £94,000 (about $118,000), which was shared between the MRC and the University of Cambridge.
Once the Hutchison/MRC Research Centre got the green light, Critical Airflow coordinated closely with lab managers to make sure disruption was kept to the absolute minimum. The 1-month process went very smoothly. Building managers immediately began receiving very positive feedback on improvements to air quality. (One somewhat amusing side note is that the extreme reduction in ventilation noise levels caused some occupants to notice other building noises that had previously been drowned out. Within a few weeks that concern went away.)
As shown in Figure 2, the day the system was switched on, the baseline air flow went from 1000 liters per second (L/S) down to 200 L/S. The team then waited with bated breath for the arrival of the first quarterly energy bill to determine if the actual results matched the goals.
The results were extremely positive. 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 energy costs by 40-60 percent in laboratory spaces. The system payback was less than 2 years. In addition, the system reduced carbon emissions by 422 metric tonnes per year (about 464 US tons per year).
Figure 3 summarizes the data on savings. “The initial reduction was like falling off a cliff, but the long-term results are even more impressive,” says Critical Airflow Europe’s operations director Chris Mulholland. “We now have 4 years of energy savings that show improvements increasing year over year. The system is still performing well and is paying back even more than we estimated.”
Figure 4 shows the gas consumption before and after project implementation. According to Mulholland, research center 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.
This project received a lot of notice and was highly commended in the Green Gown Awards Technical Innovation for Sustainability category in 2014. In announcing the award, judges said, “Sometimes institutions need to be leaders in applying existing technology to new areas. This project does this very effectively by applying variable ventilation controls to complex and high-risk laboratory settings to good effect. The demonstration of the short payback period is persuasive and should enable other institutions also to take the plunge.”
The system can be applied as a retrofit or 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 center,” concludes Richardson. “We achieved our main goals of improving the laboratory environment for our occupants, reducing the environmental impact of the research center, 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, founded in early 2000 by the management of Phoenix Controls Corporation, is the smart airside efficiency company providing building owners with sustained energy savings through its intelligent measurement solutions. By addressing the inherent deficiencies in conventional approaches to energy efficient building ventilation, Aircuity’s smart solutions deliver significant energy savings for a wide range of commercial, institutional and lab building applications without sacrificing occupant comfort, productivity or safety.
For more information about Aircuity and how we can provide you with their demand control ventilation solutions contact us today at 860.291.8886, email Tom Proietti or Cheryl McIntosh. You can also visit us on the web. Don’t forget to follow us on social media: Twitter, LinkedIn, Google+ and YouTube!