A Science-Based Approach To Controls

Aug 15, 2023
A Science-Based Approach To Controls

The combination of LED sources, circadian tuning and smart lighting systems have opened new avenues for lighting professionals. But without the data at your fingertips, the choices can be overwhelming.

Lighting color temperature and brightness are two crucial factors that influence our circadian rhythms and, in turn, influence productivity, mood and health. We can take control of how our artificial lighting affects us by automating and optimizing it to best suit our circadian rhythms and lighting requirements. LED technology and controls provide us with more authority over our litenvironments, enabling us to optimize our lighting experience for visual comfort, health benefits and energy efficiency. Choosing the right LED controller for our needs, out of the wide range of those available, will significantly impact our success.

In this article, we’ll explore:

  • How lighting impacts our circadian rhythms
  • What the ideal color temperature and lumen output is depending on setting and time of day
  • How to control smart lighting, different types of LED controllers, and what automation to implement, including daylight harvesting and circadian lighting

1. The Empirical Impact of Lighting On Health. Setting the ideal lumen output and color temperature for a space is critical when it comes to the regulation of our circadian rhythms, which has a significant impact on our health. You can calculate the ideal lumen output (brightness) based on the square footage of a room, including ceiling height. For example, a 30,000-sq ft manufacturing facility (with 9-ft ceilings) would ideally have a lumen output of about 3,044,000 lumens. The required amount of lumens for a space is also influenced by wall color. Lighter wall colors reflect more light, increasing the overall brightness of a space, while darker walls absorb more light. In addition, lighting brightness and color temperature both play a role in regulating our circadian rhythms, impacting many of our physical, mental, hormonal and behavioral changes (such as eating habits). Circadian rhythms naturally correspond to the presence of certain wavelengths of blue light, which are emitted by the sun, artificial lighting, and the screens on digital devices. Research shows that when blue light of this wavelength hits our eyes, it meets a light-sensitive protein in our retinas that governs physical changes in our bodies. This retinal protein plays an important role in setting our natural rhythms and can suppress melatonin. The artificial blue light that we’re exposed to unnaturally at night (via phone screens, for example) can confuse and disrupt our circadian rhythms, and lead to corresponding health issues. For example, melatonin is released in the absence of sunlight, and this helps us fall and stay asleep. Thus, exposure to blue light at night could eventually lead to sleep-related short and long-term health issues.

Figure 1

2. Ideal Lighting Color Temperature and Brightness. Although ideal lumen and CCT levels vary depending on the time of day, there is still a standard of measurement that determines the ideal range of both. The Kruithof curve (Figure 1) is the result of a 1941 study, which concluded that lighting conditions within the defined region of the curve were often viewed as being comfortable or pleasing, whereas lighting conditions outside the defined region were considered uncomfortable or harsh. The Kruithof curve is also in line with another phenomenon called the Purkinje effect, which shows that as illuminance decreases, human sensitivity to blue light increases.
Note that the Kruithof curve is not an infallible law. Scientists have criticized the documentation of Kruithof’s methods, commenting that Kruithof did not describe his methods of evaluation, independent variables or test samples. Larger studies have suggested that lumen output in a space has a more significant effect than CCT levels; they concluded that light-level intensity should not be under 300 lux in general. This is not to say that color temperature doesn’t affect human health, it does, but primarily when considered in conjunction with brightness. These are a few of the approximate CCT levels that are typically used in specific contexts to promote health, comfort and productivity. In general,they are:

  • 2700K to 3500K—warm lighting for residential, hospitality and other relaxing environments
  • 3500K to 4000K—cool lighting for office and commercial spaces
  • 4000K to 5000K–daylight for industrial and manufacturing applications

Color temperature in artificial lighting has been affecting our circadian rhythms since the invention of the incandescent light bulb in the late 19th century. As technology advanced, fluorescent and HID bulbs replaced incandescent lighting in commercial and industrial settings. This was, in part, because they could offer a cooler color tone, even if it was unflattering. In the 1990s, the development of blue LEDs allowed for the creation of white light. This enabled lighting with cooler color temperatures to have a more natural, pleasant light quality. LEDs are also, of course, much more efficient than fluorescent and incandescent lighting, typically converting 95% of their consumed energy into visible light (and only wasting 5% of consumed energy as heat).

3. Controlling Smart Lighting. With the use of LED controllers and sensors to collect lighting data, it is now possible to creatively customize and automate LED lighting with precision. It also helps that modern LEDs can emit virtually any color temperature. Smart lighting allows lighting to be monitored, controlled and automated remotely with an LED controller. Depending on the LED controller, this can often be achieved from anywhere in the world using a smartphone (as long as there is internet access), and voice commands. This level of control and flexibility can enhance the ambience of homes and workplaces alike, and additionally provides further opportunities to save energy. Two of the automations one can use to save energy, and improve the lighting in an indoor environment, are daylight harvesting and circadian lighting.
The purpose of daylight harvesting is to conserve energy in lighting applications, as well as maintain a consistent light level throughout the day. To implement daylight harvesting means to automate dimming based on the availability of natural daylight, thus producing the optimal illuminance with a combination of both natural and artificial lighting. Daylight harvesting can be combined and enhanced with circadian lighting so that both lighting brightness and CCT levels are changed throughout the day (Figure 2). The purpose of circadian lighting is to align the ideal lighting color temperature with the time of day, so that CCT levels align with our natural circadian rhythms.

Figure 2

To implement daylight harvesting, it’s necessary to use daylight sensors or indoor environmental quality (IEQ) sensors (Figure 3) that can detect light levels and color temperatures in a space. Data from these sensors can be sent via a wireless mesh network (for example) to a lighting controller. If this lighting controller is set up for daylight harvesting and color sensing, it has been programmed to analyze lighting in a space and automate artificial light levels and color temperatures respectively. Implementing daylight harvesting saves energy because it automates lighting to only produce the required amount of artificial light. Depending on the space and naturally available light, this type of control can reduce the energy consumption of lighting systems by up to 60%. For further energy savings, lighting can also be automated based on space occupancy.

Figure 3

Meanwhile, LED controller options include wired, wireless, digital and analog. Wireless digital LED controllers are becoming more common, especially in residential applications, as companies release all-in-one smart lighting solutions. These systems often come with compatible cloud-based apps that allow lighting to be controlled from anywhere (as long as there’s internet access). Other common LED controllers include DALI or DMX controllers. These are wired, digital controllers that use the DALI or DMX communication protocol. These are mainly used in commercial applications because they can typically support more complex lighting installations. Many of these control systems are integrated with “digital-twin” software, which serves as a real-time digital representation of the physical lighting system (Figure 4). There are many options for wired digital LED controls, and the best option typically comes down to what’s the easiest to inte grate for your specific project.

Figure 4

Some LED controllers, such as the ones with cloud apps mentioned above, communicate wirelessly. Wireless communication in LED control systems is typically either point-to-point or over a wireless mesh network. Wireless signals in LED control systems are typically RF (radio frequency). RF LED controllers, send a radio signal to a receiver connected to LED lights. The receiver then decodes the signal and changes the LED lights’ brightness, color or pattern according to the controller’s command. RF LED lighting controllers operate on a specific frequency band and have different ranges, depending on the communication protocol, environment, and the quality of the controller—and receiver. The general rule of thumb is that the higher the RF, the shorter the communication range, and conversely, the lower the frequency, the longer the communication range. This means that Bluetooth (or BLE/Bluetooth low energy) will have a shorter range than something like ZigBee. This is because Bluetooth operates at 2.4 GHz, while Zigbee operates at 915 MHz (in North America). RF controllers in general are popular for their ease of use, convenience and flexibility, as they do not require any physical connection between the controller and the lights. They are often used in residential settings, as well as in smaller commercial applications like restaurants and retail stores.

The next factor to consider is how and where to deploy smart lighting in a commercial or industrial building. This typically requires a lighting controller that has the power and customization options to support many different lighting “zones.” A lighting zone is a designated area within a building or outdoor space where the lighting is controlled together as a group. There can be many lighting zones within one building or space, and lighting zones are either grouped via programming and wireless communication, or groups are physically wired together. Wired lighting zones, as you can imagine, are less flexible than wireless lighting zones, which can be regrouped remotely through their programming (sometimes also known as dynamic rezoning). Examples of lighting zones in a commercial setting include boardrooms, and manufacturing zones that could be separated by walls, or times of use. Manufacturing zones could include quality control, cutting and machining.

LED controllers with digital twins are also very handy for commercial applications because they allow large systems or spaces to be controlled through a real-time digital representation of a space, such as through a digital floor plan of a manufacturing facility or commercial office. Through digital twins, lighting can be adjusted in real-time by clicking on an accurately placed icon. This makes control very intuitive. Digital twins can also be created and updated in real-time with computer software, programming and sensor data. Sensors could be located throughout a physical space or system to collect lighting data (for example), and then they could send sensory data to the digital-twin platform.

Digital twins simulate, and often analyze, the actions performed in a physical space or system. So, the more data that is sent to them via sensors or otherwise, the more accurate and detailed they are. Using a combination of digital-twin software and sensors is a great way to obtain practical insights into the performance, maintenance and optimization of lighting systems in commercial applications.

Digital twins of commercial buildings have been typically controlled via remote desktops, but the future of digital-twin usage will be more convenient for users. Ideally, they will be controlled with cloud-based apps, similarly to how smart lighting is often controlled in residential lighting systems. One of the main technological challenges to overcome before commercial digital twins can be controlled via a cloud-based app, is the ability for apps to communicate with pre-existing lighting system protocols, such as BACnet, in real-time.

BACnet system protocols are widely utilized in building automation and control networks, enabling different systems to communicate with each other. Simply put, BACnet protocols allow equipment from different vendors to communicate with each other, which allows existing building systems to expand without the need to worry about compatibility with new equipment. BACnet lighting controllers can be integrated into a building’s larger BACnet system (even if they are from a different manufacturer), and this allows for systems to be centralized, and more easily monitored from a remote desktop that natively controls a building’s systems. Once implemented in commercial settings, cloud-based apps would be separate from a building’s native BACnet system, so these apps will need to utilize a BACnet language bridge in order for the app and BACnet to communicate.

Cloud-based apps with digital-twin software, and this language bridge, would greatly enhance user convenience and experience, especially in commercial applications. With the ability to control commercial lighting systems simply by logging into an app, more users would be able to securely monitor, control, automate and optimize lighting systems from anywhere in the world.

To summarize, LEDs have truly revolutionized the field of lighting technology. Their adaptability in terms of color temperature and brightness empowers us to automate artificial lighting that syncs up with our circadian rhythms, ultimately boosting our overall health and well-being. The impact of brightness and CCT levels on health is significant. Acknowledging this, and automating our lighting systems appropriately, combined with the ideal LED controller, makes a big difference for energy efficiency, health and comfort.

For a more intuitive lighting control experience, the use of digital twins has also emerged as a promising tool to optimize lighting design and operation. As the field of lighting technology