What is the future application of wireless lighting controls in critical applications such as a health care environment? Wireless lighting controls are a rapidly growing technology offering all of the benefits discussed above which tend to make it a natural choice in a typical commercial facility, however, it is not yet as popular in critical facilities such as hospitals or other health care facilities. Most spaces within a health care facility are exempt from automatic lighting controls, specifically in spaces where patient care is directly administered.
However, they are not exempt from bi-level, dimming or some of the daylighting response requirements which means that the need for sophisticated lighting controls is still prevalent in a health care facility (see Table 1). Nevertheless, health care facilities present a different set of challenges when considering wireless lighting controls:
These are all valid concerns that must be addressed to bring a level of comfort to designers, contractors and owners alike before they are willing to accept the wireless technology in their facilities.
Hospitals contain a vast amount of secure data including information that is required to be protected from fraud and theft by the Health Insurance Portability and Accountability Act. This is one of the reasons why security is a real concern with any wireless system in health care facilities. A wireless system that operates on a typical Wi-Fi system may be vulnerable to the cyberattacks, cyberbombs and trojans that we hear about almost on a daily basis.
However, reputable companies that design commercial wireless lighting control systems do not operate on standard Wi-Fi signals. The majority of wireless lighting control systems are designed to operate off ZigBee protocol, an IEEE 802.15.4-based protocol that operates off a low-power, low-bandwidth wireless connection. This provides a completely separate network from the hospital’s network; therefore someone could not hack in to one network to access the other and obtain confidential health care data.
Until recently, there has not been a standard of security for these wireless control systems to adhere to, therefore the possibility exists for a manufacturer to neglect these important security measures.
To combat this, UL recently created standard UL 2900-1: Standard for Software Cybersecurity for Network-Connectable Products with the first edition published mid-2017. This standard is not yet enforced throughout the United States, but with its inception, manufacturers have made several advances in security over the past six months with anticipated national adoption.
The requirements of UL 2900-1 include end-to-end encryption. UL maintains a database of cyberhacks and built a standard to test products against to ensure that the cyberattacks can be withstood through the network connected products thereby making them future-proofed and nonpenetrable.
Another concern with using wireless lighting controls in a health care facility is the potential for signal interference. There are so many systems in a hospital, with more and more relying on wireless networks, there is the potential for interference between systems. Any interferences could create improper operation of the systems. Asset tracking, computers, real-time locating systems, nurse call, way finding, mobile phones, refrigeration monitoring, building management, medical device data collection and patient apps (to name a few) all have wireless options.
Fortunately, while an IEEE 802.15.4 communication such as ZigBee uses a similar frequency as standard Wi-Fi (2.4 gigahertz), it uses completely different channels. This reduces the risk of conflicts between wireless systems. If two systems are on same channels interference is inevitable, but if all devices are set on channels that do not overlap, they will operate as designed. In addition, IEEE 802.15.4 is a “self-healing” true mesh network that senses the other channels available; if it detects something on the same channel, it will automatically change to a different channel.
Interference prevention, in addition to the security measures discussed earlier, is yet another rationale that directs designers away from using ordinary Wi-Fi-based technology for lighting controls systems. In the future, we may see best practices include a third-party integrator during the installation process to manage the multiple wireless signals in a health care facility to ensure they are properly commissioned using different channels. This would further alleviate interference concerns.
Lighting controls reliability
Owners may experience anxiety about the reliability of the controls. After all, when automatic motion sensors first hit the market, they were certainly not perfect. Many of us have memories of frantically waving our arms to get the lights to turn back on in an office and recollections such as these justify the hesitation to embrace newer technologies. Technology has come a long way, but wireless technology is not perfect and there are some limitations that must be understood to design the systems properly.
For wireless devices to properly communicate, they must be in range with each other to ensure reliable signal transmission. Proper location of devices must consider all aspects of the building structure. A typical ZigBee wireless signal will communicate through only two or three interior walls of standard Sheetrock. In a health care environment, most walls go up to deck, so this must be considered when placing devices in a crowded plenum space. Concrete or metal walls, which also prevail in health care facilities, will severely impact wireless signal strength, reducing overall coverage and performance.
There is also concern about reliability with respect to patient safety; a facility cannot afford to literally “go dark” due to technology downtime. To overcome this apprehension, the design and construction team should ensure that they are using only products that default to a state that does not leave the patients and building occupants at risk. Most manufactures include this in their designs, and the engineer should include in the specifications that fixtures must default to at least 70% power level or greater in the event of loss of power or components.
For wireless lighting controls to become the norm in health care applications, education will be crucial. Fully understanding potential failure points and the measures to properly protect against them will allow for proper evaluation and informed decision-making. Proper system design is the key to successful implementation.
There will always be a challenge to balance what is “tried and true” with pushing the limits on “new and better,” coupled with just meeting code-minimum versus providing high-performance best practice solutions. As engineers, our job is to fully evaluate all options to help inform our owners to make a fully informed decision. At the end of the day, we want to provide a code-compliant, energy-saving solution that is easy to specify, install and manage.
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