System Review Cuts Energy Bills

The facilities management team at Glasgow Science Centre has cut energy bills by an estimated 55 000 a year,simply by reviewing it's operational profile and by reprogramming the Honeywell building management system to take these into account

The Centre opened in 2001 and comprises a Science Mall with three floors of exhibition space, caf,shop,lab and planetarium, plus an IMAX Cinema and the 105 metre-high Glasgow Tower.The Tower is the only building in the world that can rotate 360 from the ground up.

The Honeywell building management system, complete with an Excel Building Supervisor (XBS), monitors and controls the Centre's heating, ventilation and air conditioning (HVAC), lighting and fire detection.

For around 70 days each year, the Centre is open outside its normal hours to accommodate special evening events IMAX film screenings, for example.The complex and diverse nature of events means that programming the BMS to accommodate them is no trivial task, but the challenge is simplified using the XBS.

"Excel Building Supervisor enables end users to reassess their control needs and to make improvements to their control strategy," says facilities manager,Alan Cuggy, "We've been able to realise a big saving in energy consumption by using the controls properly."

Before the review work could start, Alan insisted that his team should be trained to use XBS effectively."I've worked at various sites where the BMS is not always working as originally intended,"he says,"People must be aware of what the technology can do in order to optimise it."A two-day Honeywell 'refresher'course was a prime motivator for the subsequent system improvements.

The first priority was to create programs for all eventualities.This meant considering different scenarios for each part of the Centre and programming the BMS to execute suitable lighting and heating profiles for them.

Even without the consequent energy reductions, the exercise would have proved its worth.Rather than spending time adjusting dozens of individual controllers for different functions, staff simply choose the appropriate event option from the programs already prepared.

The facilities team then turned its attention to the individual building management subsystems. A Honeywell Building Solutions engineer,who works at the Centre as part of the service agreement, reprogrammed the lighting system to deliver bespoke control for different parts of the complex and also set up lighting patterns for typical events. For evening film screenings, for example, lights in the IMAX Cinema are turned on while the rest of the complex remains in darkness.

Some parts of the Centre, including the exhibition areas and restaurant,have large windows and glass walls that let in plenty of daylight. A pair of new daylight sensors fitted to the north and south elevations of the building now link to the BMS, which switches off the lights in these areas when the average light reading reaches a predetermined level.This has had no adverse effect on the working environment.It took staff a week to notice that the lights were turned off on a sunny day.

Heating and ventilation also operates more efficiently under the new regime.The computer suite used to depend on the Centre's main chillers for 24-hour temperature control. Likewise the IMAX Cinema has a heavy cooling load for its projectors.Now both zones are switched to local secondary cooling at night and the main chillers, along with boilers and air conditioning,can be shut down.Alan Cuggy's team has also taken data from the BMS and modified the boiler control software to make sequencing changes. Sometimes only a single boiler will be running rather than all three, thereby improving efficiency.These changes save an estimated 900 000kWh a year.

Simple modifications to the control software have enabled more cool air from outside to be drawn into the building for ventilation, adding to the energy savings.

"We've also linked the BMS to our half-hourly meter reading,"says Alan. "We can now pinpoint the daytime load for any half-hour period.As a result, the Centre can cut or balance the total load, so it that does not exceed the maximum demand agreed with our electricity supplier."

Although relatively simple, these measures have had a significant impact on Glasgow Science Centre's energy costs. The estimated annual savings breakdown is:

• Boiler controls, local chilling 30 000
• Greater use of outside air for air conditioning 20 000
• Enhanced lighting controls and scenario setting 5000
• Exterior light sensors for lighting control 1400