An ABB control system at a Swedish university library has reduced electricity and heating costs by up to $220,000 a year and helped the library achieve international recognition for student satisfaction with the library's physical environment.
Anyone who has sat reading in a library for hours at a time will know how important the physical environment is. The air has to be fresh and the temperature conducive to studying. Stale or warm air will make you sleepy, cold air will make you shiver and lose focus.
Jönköping University in southern Sweden has about 12,000 students and 800 employees. Recently, the university's library was awarded a top-ten ranking by students for the excellence of its physical environment in an international comparison of 238 university libraries.
In 2011 the university's property management company, HÖFAB, which looks after
85,000 sq m of campus buildings, decided to switch from its aging multi-vendor building control system to a simpler and more efficient alternative.
After putting the project out to public tender, HÖFAB selected a control system based on ABB's System 800xA Extended Automation. The solution includes AC 800M controllers, S800 I/O, local operator control panels, and new temperature and carbon dioxide sensors.
HÖFAB has chosen to decentralize the I/O units and distribute them throughout the many campus buildings. "This reduces the cabling and makes it easier to program changes," says Mikael Falk (left)
of HÖFAB to Gert Svensson of ABB.
The new 800xA control system processes signals from around 1,000 sensors and controls more than 3,000 fans, dampers, valves and other objects in the ventilation and district heating systems. Each operator panel provides an overview of all the alarm points and enables HÖFAB engineers to control all the system objects and check the air quality of each room.
"One of the big improvements of the new control solution is that we've switched from a presence-controlled ventilation system to a demand-controlled system that uses carbon dioxide sensors," says Mikael Falk, operations engineer at HÖFAB with responsibility for the university's building automation systems.
"With the old control system, the presence of just one person would activate the room's ventilation system. Now the ventilation system is activated only when the amount of carbon dioxide in the room reaches a certain level."
Other energy-saving features of the new ABB system include the precision control of large fans and 18 kilowatt motors that blow air upwards through a seven-storey building. Previously the fans and motors were permanently operating at full speed, now they are operating at just 35 percent of their full speed thanks to the 800xA control system.
"All in all we estimate energy savings of between $150,000 and $220,000 a year in reduced power and heating consumption," says Mikael Falk.
As for the students who use the library on a daily basis, the verdict on the quality of the air is overwhelmingly positive. It's one of the reasons why they voted so highly for the excellence of the library's physical environment.
The solution was provided by local ABB partner Goodtech Project & Services.