By Kevin Callahan
At the most basic level, a building automation system (BAS) helps reduce operating costs and equipment replacement capital costs by only running systems when they are needed. For example, facility professionals could use a BAS to raise air-conditioner set-points or turn off the system in college dorm rooms in Toronto in the spring and summer, or lower heating set points in Edmonton commercial office buildings on winter weekends. The dual result is lowering utility bills year-after-year, and longer life for the HVAC equipment due to fewer annual operating hours and less frequent on/off cycling.
A properly equipped BAS can also help manage building ventilation costs. Installing wall units with carbon dioxide (CO2) sensors enables the system to determine when fresh air is needed for occupant comfort and health, rather than continually bringing in outside air. As heating or conditioning outside air is a large part of HVAC costs, this is a growing focus for many facility managers. The types of buildings in which this particularly makes sense, are those with highly varying occupancy over time, such as schools, office buildings, and government facilities.
Benefits with BAS
In addition to saving HVAC energy costs, a BAS can reduce lighting costs, which are typically the second-largest energy demand in many commercial and institutional buildings. Facility professionals are also increasingly using BAS to manage plug loads, such as those in which office employees leave on task lights or computer monitors at the end of their work day.
Although building owners typically think of BAS only for cost savings, the systems also offer revenue generating opportunities. For example, facility managers can use data provided by a BAS to document building operating costs outside tenant leased spaces, and recapture those costs from tenants. So, in an office building, the owner could bill tenants for operating costs (such as heating and lighting) related to hallways or other common-use areas. Or, a school that rents its gymnasium for community recreational programs could recapture costs from those users for ancillary space use such as corridors and foyers.
By enabling better monitoring and control of building systems, a BAS can reduce utility costs by about 15 per cent. The savings for most buildings range from $2.48 to $4.96/m2, according to the Metropolitan Energy Policy Commission, which is located in the cold-climate Minneapolis/St. Paul region.
Achieving such cost savings requires facility professionals to be able to readily retrieve and make use of performance data the BAS generates. Such building analytics are the heart of a ‘smart’ building, and are what makes a BAS more than a glorified, programmable thermostat that turns off the HVAC equipment and other building systems according to a fixed schedule.
Building analytics provide facility managers the information needed to optimize building performance. This could include actions as seemingly simple as ensuring they are not simultaneously heating and cooling the same building area or that lights are turned off or dimmed when the building is vacant. A BAS can also help with specialized facility needs, such as an airport that needs to determine how many escalators really need to be kept on in the early morning when only a few passengers are in the terminal, or a hospital that wants to figure out the best timing for posturing its surgical suites.
Making the system as efficient as the building
Although a BAS can save a facility’s owner thousands in annual energy costs, many users do not achieve the full benefits. The problem is a number of systems are not intuitive to use, so their capabilities go untapped. Earlier iterations of some assemblies seemed to highlight a design conceit in which people should adapt to the machine, and if not, too bad for them.
BAS manufacturers are now taking a different view of their systems; they are understanding the machines need to be adapted to people. As a result, some automation systems incorporate human-centred designs to make software, wall units, and control modules simpler to use, while still providing powerful functionality. The intent of this design philosophy, which centres on ‘usability testing,’ is to “empirically evaluate the usefulness, effectiveness, and acceptance of a product at various stages of the design process,” according to Carolyn MacGregor, an associate professor at the University of Waterloo.