Intelligent Building Management is Fast Becoming the Way to Save Money
Though we all know the nine-to-five workday is a relic of a bygone era, the buildings we work in are frequently unaware. Lighting, if automated at all, often starts shutting down at a prescribed time even though staff may be working into the night. HVAC systems that require manual switching from winter heating mode to summer air conditioning, usually don’t get switched over until employee complaints become too loud to ignore.
Enter intelligent building scheduling. Play it smart and it becomes possible to use lighting in a targeted manner that is easy on employees’ eyes as well as the wallet. And by tying building controllers into facility scheduling software, spaces, such as conference rooms and classrooms, can be brought to an optimum temperature prior to the start of an event.
“The most effective lighting scheme is one that incorporates ‘daylight harvesting,’ that knows the angle of the sun, whether it’s cloudy or bright, and where the sun is facing in relation to your facility, according to the astronomical calendar for your latitude and longitude,” says Michael Carter, director of Building Automation Solutions at AMX. “There are also lots of other data points to consider, such as how many people are in a room at a particular time and whether the order in which rooms can be booked should vary based on time of day and the amount of natural light each one receives.”
For Kirk Davis, managing principal at the Portland, Ore. Office of sustainable engineering firm Glumac, leveraging maximum daylight comes first when developing any intelligent automated facilities schedule, whether building from the ground up or retrofitting an existing structure. For him, even though daylight is free, it can be harnessed to varying degrees based on the age of an existing building and the extent of updates. With the right tools and an approach that’s flexible enough to change as the project progresses, retrofitting is no longer the challenge it once was. Those tools include automated window shades and sensors to detect the presence or absence of people.
Occupied or Not?
Occupancy sensors, used to turn lights on or adjust temperature when someone enters a room, are not always the best choice for overriding a preset facility schedule. In spaces that do not benefit from natural light — bathrooms, windowless lecture halls, and printer alcoves among them — it makes sense to use occupancy sensing to turn lights on. In other spaces, the contrarian strategy of using sensors to detect the absence of people often makes more sense.
One tip for efficient facility management relates to energy and occupancy sensor best practices, according to Glen Marianko, technology manager for Enterprise Software at Crestron. “You don’t always want to use sensors to detect when people are present. It’s often smarter to do the opposite and detect vacancy, the absence of people.” In a simple scenario, Marianko says an employee attending an afternoon meeting might dash into his or her officeat 6 p.m. to grab keys and briefcase then head home. Instead of having an occupancy sensor turn on the lights which might be needed for just a few seconds, it’s better left to the employee. “Let the occupant decide to switch on the light and use the vacancy sensor to turn it off after a brief period of inactivity.”
The question, of course, is how quickly to turn that light off. Through the use of controllers and software from AMX, Crestron, Lutron and others, the timeout value can be varied by time of day. “You want the timeout to be long enough so that lights are not turned off when people in a conference room take a 20-minute coffee break, but you may want to shorten the timeout to five minutes after 6 p.m.,” says Doug Jacobson, vertical markets manager for Lighting and Energy Management at Crestron.
Since lighting is instantaneous, there’s no need to prepare a space more than a few minutes before scheduled use, mainly to accommodate early arrivals or set-up. HVAC is vastly different. An auditorium booked for a 2 p.m. meeting in mid-July needs to be pre-cooled well before the event starts, says AMX’s Carter. “You also have to take into account the heat generated by several hundred bodies in that auditorium.”
With pre-planned and ad-hoc events continually at odds with a structured hour-by-hour facilities schedule, there is universal agreement when it comes to implementation – it’s okay to be energy efficient, but it’s not okay to be annoying. If you’ve installed sensors in a conference room to detect occupancy or vacancy, overlaying system-wide time-clock scheduling on top probably will not work. The converse, however, giving the sensors precedence over the clock schedule could work much better.
Yet, even the exceptions have exceptions. During in-session school hours, it may make more sense to have the control system disable or disregard occupancy/vacancy sensors installed in hallways to prevent lights from turning off when classrooms are full and hallways empty. After school hours, hallway lighting could switch to a low mode in which only every second or third fixture is illuminated. Sensors detecting occupancy could then turn on the remaining lights as needed for a set interval or turn them off in response to vacancy sensing. Similarly, the handling of parking-lot lighting is not simply a time-of-day matter. “You could start with a time clock, but adding a photocell may help, especially when a summer thunderstorm rolls through and darkens the sky, even though it’s 2 o’clock in the afternoon,” says Crestron’s Jacobson.
In the end, facilities managers invariably discover that intelligent building management is an iterative process that warrants periodic re-visitation. Assumptions about workday length made when schedules were initially developed may not be reflective of current employee work patterns. Desks may be shared by people working staggered shifts. Fortunately, with individual lighting fixtures controllable by flexible systems over the corporate network, keeping lighting and HVAC in sync with employees’ work patterns — while minimizing energy consumption — has never been easier.
By Joel Shore