Internet of Things: Using Wireless-Controlled Lighting to Reduce Energy Costs
Lighting represents a significant fraction of electricity usage in residential and commercial buildings. According to the U.S. Department of Energy, lighting accounted for more than 13 percent of residential electrical usage and more than 20 percent of commercial electrical usage in 2013.¹ Traditional mechanical wired lighting systems offer users few cost effective options in managing usage and controlling lighting expense. In contrast, wireless-controlled lighting allows households and building owners to tune lighting usage to more precisely fit lighting area and time-of-day requirements while simplifying maintenance and administration of large lighting systems.
Wireless-controlled solid state lighting offers substantial benefits, not only in managing energy consumption but also in providing a degree of flexibility and ease of use beyond that possible with traditional lighting approaches. For consumers and businesses, wireless lighting systems enable improved use of lighting resources despite continually changing requirements, while simplifying deployment of more sophisticated lighting and energy management strategies. For engineers creating these systems, a broad framework of silicon solutions and protocols helps simplify creation of low cost wireless lighting devices.
Lighting control applications that enable energy savings
In a typical wireless-controlled system, controllers or even personal smartphones communicate with these MCU-based luminaires, using two-way wireless communications to collect operational status and issue commands to the wireless lighting device. Along with basic on/off and dimming control, wireless-controlled lighting systems enable more sophisticated lighting management such as scheduling illumination levels at programmed times, controlling illumination based on room occupancy, and tuning both color and brightness to match the user's task, work area and preferences.
Beyond these user-directed features, these systems play a key role in supporting building management services and simplifying implementation of energy saving strategies. Wireless luminaires can perform self-diagnostic functions and transmit lamp usage reports and even warnings of potential failures to operators to help simplify maintenance and reduce cost.
For households and organizations looking to optimize energy costs, these systems can be designed to communicate to the smart grid to reduce load in demand-response arrangements. For example, during peak-rate hours, lighting can be slightly dimmed, reducing energy load and costs without users even noticing a significant change in illumination.
The composition of a wireless-controlled lighting device
In its most basic form, a wireless-controlled solid state lighting device combines one or more LEDs and its drivers with a microcontroller and wireless subsystem (Fig. 1). In addition, these devices also typically include sensors to monitor ambient lighting levels, temperature and occupancy needed to support more sophisticated lighting control applications.
Fig. 1: A typical wireless-controlled solid state lighting system combines an LED and its drivers with an analog front end, MCU and wireless interface. (Source: Texas Instruments)
The ready availability of a wide range of low cost MCUs with integrated RF transceivers has simplified development of wireless luminaires. For example, MCUs such as the NXP JN514x, Silicon Labs Si202x/3x, and Texas Instruments CC430F61xx, among others, combine an MCU core, on-chip memory, ADCs, peripherals, and RF transceivers needed to design sophisticated wireless lighting devices with few additional components beyond power and LED driver circuitry.