Connected RTUs Take the Next Step
Smart rooftop units can monitor, adjust, detect, and diagnose indoor environmental conditions
The rooftop unit has long been seen as the workhorse of the commercial HVAC market. Often considered to be an affordable, reliable heating and/or cooling system for a variety of commercial buildings, the standard rooftop unit used to come with a basic thermostat that is limited to turning the system on or off. The advent of new controls has changed all of that by allowing rooftops to monitor operation, analyze conditions, and make real-time decisions that can optimize performance.
This new breed of smart rooftop units obviously comes with a premium price, but manufacturers are betting that system owners and operators are willing to spend in order to reap the benefits of increased energy efficiency and improved comfort.
VARYING DEGREES OF SMART
There are two different types of smart rooftop units. The standard smart rooftop usually comes with an integrated, programmable direct digital control (DDC) that provides intelligence at the equipment level.
“Basically, a smart rooftop has the capability to monitor, adjust, detect, and diagnose itself and indoor environmental conditions to ensure proper building occupant comfort,” explained Brian Wathen, commercial product marketing manager, Johnson Controls Inc. “In addition, a smart rooftop provides instant feedback to end users concerning operational conditions and potential and critical issues. These units also grant users the ability to wirelessly communicate with a rooftop unit or series of rooftop units using a smartphone, tablet, or PC.”
An even smarter rooftop unit is Internet of Things (IoT)-enabled, which offers all the features listed above, but the data it collects can be transferred to the cloud, where further analytics are applied to make the unit data more meaningful.
“Basically, you’re taking a smart rooftop unit, extracting the data, and combining it with external data sources and analytics, so you can increase the unit’s IQ,” said Jim Macosko, product general manager for applied air handling, Daikin Applied. “This type of unit harnesses the power of all that data, provides predictive analysis, and then feeds that information to the building owner, who can then make smarter, proactive decisions. It’s a more holistic solution.”
The biggest difference between a smart rooftop unit and an IoT-enabled unit is that the latter comes with what is needed to connect and communicate online with the cloud, noted Shaun Thomas, senior commercial technical representative and hybrid applications engineer, Rheem Mfg. Co.
“A smart rooftop can be connected to building management systems, like LonWorks or BACnet, for remote monitoring and control,” he said. “Some smart rooftop units can be connected to the internet through additional controls or modules.”
Both types of smart rooftop units offer many advantages over standard rooftop models with thermostats, said Chris Opie, director of North America commercial marketing, Carrier Corp., including better comfort control and greater energy efficiency.
“With the ability to simultaneously sense temperature, humidity, and outdoor air contaminants [affecting fresh air], smart rooftop units can auto-adjust operation to meet comfort needs,” he said. “Smart rooftop units also save energy by collecting and analyzing data and then appropriately adjusting unit fans, compressors, refrigerant pressures, etc., to meet the required comfort zone settings and ambient conditions, such as reducing output when spaces are not utilized.”
Smart rooftop units are also easier to troubleshoot and service than those lacking intelligence as the units can better convey any potential issues.
“Standard rooftop units usually utilize an on-off control, so when service techs walk up to a unit, and it’s not running, they’ve got to go through an extensive process of elimination to figure out which mechanical component is not operating,” said Steve VanPeursem, director of marketing and sales for package systems, Daikin Applied. “If service techs sign into the tech dashboard, they can review data and diagnose the unit from anywhere and refer to the unit’s operating history. It may also give them an alarm history, so the service techs can quickly diagnose what’s wrong with the unit and get it up and running again.”
With all of these benefits, it seems like it would be a no-brainer for building owners to invest in smart rooftop units, but first cost can be a stumbling block. Smart rooftops in the light commercial range can cost 2-5 percent more, said VanPeursem, but their benefits far outweigh the initial cost.
“Building owners really need to compare the total life cycle cost of the equipment,” he said. “If this smart rooftop actually saves them from replacing a unit in five years [due to preventive diagnostics and fault detection], what is the true life cycle cost of that piece of equipment?”
Indeed, when comparing smart rooftop units to standard rooftop units, it’s necessary to consider that their respective costs are associated with their specific capabilities, said Opie.
“Smart rooftop units can actually pay back faster than standard units due to energy savings and integrated diagnostics that limit unnecessary service calls,” he said.
And technology will continue to improve, making rooftop units smarter than ever. Next-generation rooftops will gain more intelligence and offer even more features, such as power consumption monitoring, load shedding, cloud-based equipment data management, and integration into multiple building systems, such as fire safety, hydronic systems, and others, said Wathen.
“Wireless communication between various rooftops and other equipment will eventually reduce installation costs and complexity,” he said.
Smart rooftop units will likely become more intuitive in nature while taking on more precise control and data collection of complex components and networks, said Opie.
“Smarter prognostics and diagnostics may yield more accurate predictive maintenance and even more control of the unit from a remote location,” Opie said. “Features previously only applicable to larger size units are migrating to smaller units as technology and integrated operation improves. As these trends continue, factory integration of controls will continue to broaden and smart controls on smart rooftops will be more prevalent.”
However, building owners may need a little prodding from the federal government before fully accepting these more expensive, smart rooftop units.
“The industry has been rather slow to adopt smart rooftop technology because of the cost,” said Thomas. “When it comes to commercial applications, most business owners look for the lowest-cost equipment and not necessarily the smartest. As federal efficiency laws change and minimum efficiency requirements continue to increase, more and more systems will be required to come with factory-installed smart controls.”
Publication date: 10/2/2017