Field Devices: Case Studies in Controlling Costs and Increasing Comfort

Strategically placed field devices that can sense or control air and water temperature, as well as unhealthy levels of CO2 (carbon dioxide), are the foundation of a BMS (Building Management System). They’re also the foundation for energy and money-saving success. As a critical part of a BMS, they have been shown to reduce energy consumption by 30% or more, which often results in a payback measured in months. If you are thinking about implementing an energy-saving solution, consider these real-world case studies.

The first example helps make history by preserving it. The Abraham Lincoln Presidential Library and Museum in Springfield, Ill. is half again larger than any other presidential library. It also is the best attended, with visitors treated to an array of rare artifacts on loan from collections around the world.

The thing about artifacts is that they can’t be replaced. So, while museum visitors view documents and the like, at the same time the exhibits have to be protected. That’s why the Federal Historic Preservation Agency requires keeping areas at a constant 68o F and 45% relative humidity year-round with an allowed deviation of just 1%. That can be challenging in a place that averages a 17o F low in January and an 86o F high in July. The sheer number of visitors entering and exiting also adds to climate control difficulty.

The museum successfully solved this problem with Schneider Electric products, using controllers to manage air handlers and scientific-grade sensors to monitor humidity and temperature. The system is able to respond to changes in the heat load in just seconds. For more information, visit the Lincoln Presidential Library and Museum case study.

A second example comes courtesy of the Busey Bank, which has a 100-year old Executive Center building in Champaign, Ill. Not surprisingly given the age of the building, a lot of energy, and money, was being wasted. For instance, the entire building was a single zone running full heating or cooling.

An examination of energy usage revealed that the building wasn’t thrifty. The annual usage was about 1.8 million kilowatt-hours (kWh), more than twice what it should have been for a building of that size. As for heating, that too had enormous energy savings potential, thanks to the waste of a boiler system running at only about 60% of its nameplate rating.

Correcting the situation involved in installing Schneider Electric field devices. These include variable speed drives to adjust aid conditioner fans so as to better match cooling needs. There also were valves and actuators to regulate steam, with this making heat delivered better aligned with heat demand.

The result was an annual electric savings of 30%, with usage reduced from 1.8 to 1.2 million kWh. Annual natural gas consumption fell by more than 50%. A final measure of success would please any banker: a 100% return-on-investment in just over 18 months. For more information, see Busey Bank.

A third and final example involves repurposing and retrofitting a large building, in this case the hangers and other structures used by the Springfield, Ill.-based Illinois Air National Guard’s 183rd Air Wing. The Air Wing had a new mission to support: fixing instead of flying fighters. It also had to satisfy a 2007 law calling for cutting energy consumption per gross square foot by 30% by 2015.

For the facilities of the 183rd Air Wing, that translated into a reduction of 100,000 kWh in electricity alone. With the buildings already in place, the Air Wing had to achieve these savings by upgrading its old boilers and the field devices that controlled them or distributed air and steam. This meant installing modern zone valves and valve and damper actuators. These were combined with an up-to-date control system to increase occupant comfort and enable a temperature setback, with unused areas allowed to deviate from an ideal temperature. This can save a percent for each degree of setback over an eight-hour period.

By retrofitting its buildings, the Air Wing was able to reduce electricity usage by 30% and cut annual gas consumption by 70% while maintaining precise temperature control. The seamless integration of everything into one system makes it easier to monitor and control. For more information, see Illinois Air National Guard.

As these examples show, the right technology and the right approach can make energy management and savings take off.

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