Make Your School Control Itself
- By Michael Fickes
- 04/01/12
A typical school building — with air conditioning — will cost about $1.50 per square foot per year to operate. But schools that incorporate building automation systems and the latest lighting, mechanical and water technologies can do much better.
Tim Lehman, mechanical discipline director with Celina, Ohio-based Fanning Howey, an architectural firm that specializes in education, can point to school renovations and new construction that have driven operating costs significantly below $1.00 per square foot per year.
There are different levels of building controls. Some buildings have stand-
alone controls — light switches, zoned thermostats and so on — with no integration and no way to monitor the overall system.
“Everything we do today has a full-blown control system that schedules and controls building systems, while monitoring performance as well as incoming electricity, gas and domestic water,” Lehman says.
Two Ways to Integrate
and Control Building Systems
The key to controlling energy use in a building lies in integrating the mechanical, lighting and other building systems so that you can schedule each system, control how the systems work together and monitor performance.
There are two ways to do that, says Lehman. First, you can use a third-party, front-end package like BACnet, which is a protocol that enables different kinds of building systems and systems from different manufacturers to talk to each other.
With such a third-party package, you have to integrate the individual pieces and parts, linking the controls on systems from each manufacturer into the third party’s front end.
Third-party systems aim to be
open and not proprietary, so that any maintenance tech can troubleshoot or
fine tune the building control system
and components from one manufacturer can replace components from another.
According to Lehman, however, building system integration isn’t as simple as buying a new printer and simply clicking a few buttons to get your computer to talk to it.
“Suppose you buy a major national brand air conditioning unit and tie it
into a third-party, front-end system,” Lehman says. “You can control certain things, like scheduling the unit, but
if you want to change how the unit
operates by, say, adjusting how far the outside damper opens, then you will
need a software tool from the manufacturer to change the equipment’s
programming.”
The other approach, continues Lehman, is to choose a proprietary building automation system provider like Milwaukee-based Johnson Controls or Munich-based Siemens.
A proprietary company will install
its controls in each of the different systems, from HVAC to the lighting
and water systems. Then, the provider will tie those controls into a proprietary front-end system with a user interface that enables a user to control, monitor
and analyze all of the building’s
systems.
Decide Early
Lehman recommends deciding on the kind of building system control and monitoring systems you want at the beginning of the project.
“For us, it makes sense to choose to monitor all the utilities coming into the building — electricity, natural gas and water,” he says. “That enables you to build a database that records consumption and compare consumption over time. That way you can evaluate improvements you have made. Are they helping or hurting?
“You will also be able to detect systems as they fall out of sync and cause you to use more electricity, gas or water.”
Another early decision related to energy involves whether or not to integrate the indoor and exterior lighting into the building automation system.
If you choose to integrate the lighting, you can use the same software application to schedule the HVAC for a part of the facility, the gym for example, and the lights in the gym.
Still another issue to consider upfront deals with tying your card access control security system into the building control system. That way, when the football coach cards in on the weekend to review video of his team’s next opponent, the building system will turn on the HVAC system and lights in the coach’s office.
You might want to think about tying the fire alarm monitoring system into the integrated system too. It’s easier to manage all of these things from a single user interface.
Addressing these issues up front enables the design team to work out key preliminary details that smooth the way to completing the project.
Renovating St. Henry
Fanning Howey designed additions and renovations for the St. Henry Elementary School and St. Henry High School in St. Henry, Ohio. The work was completed in 2002, so there has been plenty of time to track and evaluate the results.
Both were older schools and had old-fashioned building controls. Each school was using classroom unit ventilators — one in each classroom, floor-mounted on the exterior wall.
“We removed the old ventilators from each school,” says Lehman. “In the elementary school, we put new unit ventilators back in as well as a new air conditioning system.
“We used direct digital controls (DDCs) from a proprietary manufacturer on the HVAC and lighting systems throughout the building.”
The results have been exciting. The 65,700-square-foot elementary school has seen operating costs fall to $1.03 to $1.10 per square foot per year.
The 135,300-square-foot middle school-high school costs have slid down to $1.10 to $1.13 per square foot per year.
“These are excellent costs, probably close to what both schools were paying before the renovation — but now both have air-conditioning,” Lehman says. “According to an ENERGY STAR tool that compares how buildings operate against average buildings of the same size and use, these schools are operating 28 percent more efficiently.”
The Coldwater K-12 Renovation
Fanning Howey also designed the total renovation plus an addition to the Coldwater K-12 School in Coldwater, Ohio. The 47,000-square-foot addition tied two existing buildings together and brought the total floor area to 243,000 square feet.
This school, too, was using classroom unit ventilators and had no air-condi-tioning. “Here we installed variable air volume (VAV) systems in most areas,” Lehman says. “We did replace a few unit ventilators in areas where we couldn’t install VAV — there wasn’t enough room above the ceiling for the new ductwork.”
Now fully air-conditioned, the building received an ENERGY STAR certification upon completion in 2006.
Proprietary building system controls encompassing the lighting and HVAC systems enables operators to monitor and schedule systems and maintain costs in the range of 85 cents to 93 cents per square foot per year, about the range it was operating in before the air conditioning system came on board.
Chilled Beams for the
McPherson Middle School
Opened for only a year, the new 85,900-square-foot McPherson Middle School in Clyde, Ohio, combines a newer chilled beam heating and cooling system along with building automation controls to achieve an operating cost below 80 cents per square foot per year.
A chilled beam system uses a heating coil and cooling coil integral to the diffuser, which is shaped like a beam. “Using a dedicated outside air system (DOAS), we deliver conditioned ventilation air from the outside through the chilled beam,” Lehman says.
The DOAS units have conditioned and dehumidified the outside air and tempered it to room neutral conditions — it is now room temperature and dry. The air handling system delivers the conditioned air through high velocity nozzles in the chilled beams. The pressure change induces air from the room below up through the heating or cooling coils. Once the inside air has been heated or cooled, it mixes with the ventilation air and flows back down into the room below.
According to the American Society of Heating, Refrigeration and Air-condi-tioning Engineers (ASHRAE), chilled beams require 50 to 65 percent less air than a VAV system, smaller ductwork and smaller air-handling units. So they reduce operating costs.
“Chilled beams are very energy efficient because the air handling units only have to move the ventilation air, not the entire amount of air required to heat or cool the space. This is typically less than half of the typical air flow needs for a VAV system,” Lehman says. “In addition, because there are no moving parts, chilled beams are nearly maintenance free.”
The efficiency of chilled beams combined with a proprietary building automation control system that integrates the HVAC system and the lighting system enables McPherson Middle School to turn in such low operating costs.
In an era of continually rising utility costs, efficient systems managed and monitored by building automation control systems can ensure that building costs don’t eat into funds necessary for education.