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Cutting energy use by 20%

Nazita Saye

Nazita Saye

Posted Sep 16, 2010

A couple of months ago I visited my colleagues in Budapest. During my stay, I was invited to take a tour of a local university where we visited an engineering studies building.  We ended up in a lab to see some equipment. As soon as I walked in, I got distracted because of the temperature in the lab. Why? Because we were visiting Budapest in the middle of a heat wave (it was about 38° celcius, 100° F outside) and the temperature inside the lab was easily in the “frostbite” range. My attention quickly drifted back to the equipment which was being packed away in preparation for a move to a new building.
As we were walking thru the building, I noticed that the hallways were not cooled at all but each lab had its own air conditioning unit … each one pumping out an enormous amount of cool air to keep the occupants and equipment comfortable. It was then that I realized that the building had been retroactively updated at some time to offer localized cooling to make sure the critical areas were kept cool.  So as we were walking down the hallway, I started wondering about their energy usage and the cost of cooling the labs especially since the building looked like it was built in the 50s and didn’t look like a very “green” building. I guess that’s why the labs were being moved to a new purpose-built building.

Purpose-built buildings using the latest/greatest “greening” techniques have become very popular and for good reason. They are more energy efficient and they cost less to operate. One such building is the new Genomic Science building at the University of North Carolina (UNC) at Chapel Hill in the States which was designed to meet a Silver certification rating under the Leadership in Energy and Environmental Design (LEED) program. This new building was designed with an active chilled beam cooling system that is estimated to deliver a 20% reduction in energy usage.  The building is currently under construction and should be completed in 2011.

The UNC was established in 1780 as America’s first public university and remains one of the most popular universities in the South.  Their $125 million building is quite impressive. It will ultimately provide an additional 210,000 sq ft of classroom space, labs and offices plus two massive lecture halls among other facilities. The active chilled beam cooling system relies on natural convection for cooling purposes and therefore reduces the need for the amount of energy required for ventilation systems.  According to an article published in a supplement of the June 2010 issue of HVR, “passive chilled beams consist of an exposed chilled water coil suspended from the ceiling. Chilled water flows through the coil and convection induces warm air from the space across the coil which falls back into the space creating a natural air flow. Active chilled beams use supply air distribution nozzles which magnify the effect of natural induction by creating a negative pressure zone on one side of the beam. Air systems are used to supply the minimum ventilation requirements for the lab while the chilled beams are used to meet the cooling loads that aren’t met b y the ventilation air.”

Affiliated Engineers use FloVENT to optimize chilled beam cooling system and cut energy consumption by 20%. Image courtesy of AEI and Mentor Graphics.

Affiliated Engineers use FloVENT to optimize chilled beam cooling system and cut energy consumption by 20%. Image courtesy of AEI and Mentor Graphics.

The engineers at Affiliated Engineers Inc. (AEI) used simulation software to optimize the design of this cooling system and maximize the energy savings. A wide range of active beam scenarios were analyzed in order to find the right design – one that met the temperature requirements for the space while reducing the overall energy consumption. The team at AEI also used the chilled beam capacities and ventilation requirements as input for an annual energy consumption simulation for the lab. The analysis predicted that the energy consumption of the lab conditioning systems will be about 20% lower than a baseline comparison for conventional designs based on ASHRAE standard 90.1-2004. It really is a fascinating concept and you can learn more about it here. And as always, if you are interested in learning more about how simulation can help you realize your HVAC designs, please pay a visit to our on-demand library for a presentation on a topic of interest.

As for me, I can’t wait to take a tour of the new facility at UNC to see the new energy efficient system in action.

Until next time,

PS. The Tarka trail was lots of fun – despite the ever present rain, I saw some stunning English countryside, found the bemused look on the sheep running around the Dartmoor as they stared at the crazy people on bikes hysterical and met some friendly locals. I feel like I’ve finally gotten to see a bit of the real England …

Energy, HVAC, chill beam, UNC at Chapel Hill

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About Nazita Saye

Nazita SayeI have been involved with the CFD user community in one shape or another since 1999 -- when the NIKA team first introduced FloWorks to the engineering community. Over the years I've seen the market evolve and I still marvel at the wide range of products that are being designed with our tools. As the Manager of External Communications for the Mechanical Analysis Division at Mentor, it is my privilege to bring some of our customer stories to you. Visit CFD doesn’t mean Color For Directors

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