Future-proof health care facilities with wireless lighting controls
As the industry continues to gain momentum in wireless control solutions, what is the future of lighting controls in critical applications such as a health care environment?
- Understand the interior lighting control requirements for typical health care facilities.
- Explore the differences between wired and wireless lighting control systems and their applications as they relate to health care occupancies.
- Review the latest energy code adoptions and the major changes to the latest editions.
One of the fastest changing technologies in the building industry today is lighting controls. The technologies are advancing in such a way to future-proof buildings in an effort to reduce that post-mortem feeling of old technology in a brand-new building. Intelligent, network-based systems with full building integration and more recently, wireless controls, are making huge advances in the market.
Total building lighting control solutions using wireless technology boast the benefits of being scalable, flexible and easy to install. But when it comes to wireless, there are certain facility types that are hesitant to accept the new technologies due to real or perceived fears. As the industry continues to gain momentum in wireless control solutions, what is the future of wireless lighting controls in critical applications such as a health care environment?
As with most aspects of building engineering design, codes and standards regulate the design and installation of building systems, including lighting controls. There are numerous energy codes and standards:
- ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings.
- California Title 24.
- International Green Construction Code and ASHRAE 189.1.
- International Energy Conservation Code.
- Various state energy codes.
Two key codes/standards are applicable to most building types: ASHRAE 90.1 and IECC. They contain pertinent requirements related to lighting controls and are widely adopted as the benchmark for energy efficiency in buildings.
It can be challenging juggling multiple codes and standards, however, deciding which energy standard applies is a consideration on every building project. Most jurisdictions enforce the IECC, and the IECC references ASHRAE 90.1 as an acceptable compliance path.
Similarly, most of the green building ratings systems mentioned above enforce ASHRAE 90.1, so it is important to have a deep understanding of both. While there is some consistency between the two, there are several nuances within each making it important to understand which code is applicable to your particular design. To check the status of current energy code adoption across the United States, refer to the U.S. Department of Energy (see Figure 3).
The application of building energy codes and standards is not a new concept to the engineering community, as they have been the standards of practice over the past couple of decades. However, they are continually updated on a three-year cycle and with each new edition emerge stricter compliance requirements. These energy codes may be confusing at times, but they consistently drive requirements for higher system efficiencies and proper application has the potential for significant energy savings.
The most current editions include the 2019 version of ASHRAE 90.1 and the 2018 version of IECC. Because the latest versions are relatively new and they are not yet widely adopted, let’s briefly review the basic interior control requirements and highlight any major updates as they relate to interior controls before diving deeper in to wireless system technologies. Note that both ASHRAE 90.1 and IECC also contain exterior lighting control requirements for parking lots and parking garages, but in the interest of brevity and relativity, this article will focus on interior controls.
The following list outlines the basic interior lighting control requirements contained in the two codes/standards (see Table 1 for a description of each requirement):
- Automatic off (full or partial).
- Bilevel lighting/light-reduction.
- Daylight responsive.
- Manual on or partial automatic on.
- Occupant sensor.
- Scheduled shut-off.
Updates to ASHRAE 90.1-2019 include a new section titled “Simplified Building Method Compliance Path,” which provides an acceptable compliance path when at least 80% of the floor area supports office, retail or school buildings. The 2019 version also includes updated lighting control requirements for parking garages, additional daylight responsive requirements and further clarifications for side-lighting requirements and associated exceptions. It also now includes a definition of “continuous dimming” based on National Electrical Manufacturers Association LSD-64-2014.
Updates to IECC-2018 also includes a new section to allow luminaire level lighting controls (LLLC, a new term to watch) as an alternate to satisfy control requirements. There are also updates to daylighting requirements and expanded occupancy sensor requirements in open offices.
Wireless controls technology
In addition to regulatory compliance, modern lighting controls can provide intelligent systems that learn when and how to adapt lighting automatically to deliver the optimum environment for the occupants. This allows the technology to be used as a state-of-the-art building enhancement, as opposed to just a regulatory burden.
What exactly is the difference between wireless controls and a hard-wired system? As you might have guessed, a wireless system is not 100% wireless. However, the conduit and wiring associated with a wireless system is drastically reduced compared to a conventional hard-wired system.
Both types of automatic lighting control applications provide the same functionality in meeting energy codes, providing energy saving benefits and tailoring the occupant experience. The basic input and output components of the two system types are the same. An input device such as an occupant sensor or photosensor sends a signal to a controller such as a relay or power module, which then controls the device or group of devices (luminaires).
The main difference between a wired versus a wireless system is the way the control signal travels. A wired system uses hardwired low-voltage or line-voltage wiring, whereas wireless communicates through radio waves. A wireless system is only wired for power, not load switching, which simplifies the installation.
Some of the touted benefits of wireless lighting control systems include decreased installation times, scalability, flexibility, lower cost and automatic commissioning. Because the systems eliminate the need for control wiring and associated conduits (leaving only that required to power the fixture itself), it lends itself to reduced installation times as well as labor and material savings. According to Eaton’s WaveLinx lighting solutions, a typical installation could save up to 6.4 hours per room over that of a traditional wired lighting control system.
Another benefit is the scalability of the systems. Because there are not wires attached to the control components and the devices are programmed remotely, they can be easily scaled — fixtures added, moved or removed — as the spaces change making them appealing for renovations or last-minute construction changes.
Wireless control devices are also flexible in that they may be installed nearly everywhere without attached wiring, thereby future-proofing the systems. This flexibility provides the user with reassignable fixtures to create new control zones and areas via web apps or other software platforms. All this can be done without access above the ceiling space for reconfiguration or user preferences.
In addition to these benefits, some manufactures also offer automated commissioning features to comply with the commissioning requirements of both IECC and ASHRAE 90.1. During the setup process, various sequences of operation, such as daylighting zone dimming or time of day controls, may be automatically applied, thereby saving more time at the end of a project during commissioning.
Applications in health care
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:
- What security measures protect the system from vulnerability?
- Will there be interference with the multitude of other systems in a hospital?
- Are the controls reliable?
- What effect could a system failure of the controls have on patient safety?
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.
Table 1: Interior control requirements
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.
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.