Guest post by Kevin Willmorth, Lumenique
The application of lighting controls includes on-off, dimming, CCT selection, and load shedding to meet energy regulation requirements. In spaces where the presence of daylight exists, automatic controls are typically deployed to dim or shut off redundant electric lighting in response to the presence of natural light. Time clocks and occupancy sensors automatically control loads as programmed. In these approaches, the user is either included in the design and programming process or by proxy through the design team or other representative. While better than no control at all, these impersonal controls do not respond to personal needs, changing task assignments, or changes in work being done under them.
In conventional hard-wired systems, changes in connection(s) between sensors and controls is typically expensive. Once the system is installed, there is little the occupant can do to change the functional connection, leaving only minor adjustments in response settings, or occupancy sensor timer settings as the only interactive feature. The advent of control technology that separates sensors from loads (fixtures) and can then “re-associate” sensors/fixtures via a processor – this creates greater flexibility, user acceptance/comfort and opportunity to make changes in controls responses without cumbersome rewiring. However, the amount of change can be limited by the number of sensors and individual luminaire control employed, and their location in relation to the users. The greater number of sensors and individual luminaire control, the greater the opportunity to tune the system to specific user demands.
Realizing this, integration of sensors and individual luminaire control offers the fidelity required to respond to specific user preferences.
Further to this, use of wired or wireless individual control, allows users to control loads directly. User control can be provided by a local wall button station, control from the user computer, control at the facility manager level and/or smart phone/tablet, and control integrated with task luminaires.
Furniture mounted, and portable desk task lighting reduces the demand on general lighting systems (saving energy) and creates opportunity for occupants to tailor the light inside their immediate area, specifically to task requirements and personal preference. Portable task lighting not only provides on-off and dimming control, it also delivers location and focus control, placing auxiliary light where its needed, while remaining off when it is not. This could be considered the ultimate in user interface and control. Further, integrating occupancy sensors into control of furniture mounted and portable task lighting causes these loads to behave as other sensor-controlled luminaires elsewhere. Additionally, task and furniture mounted lighting can also be controlled to respond directly to available natural light from skylights or windows using built-in sensors. The advantage of localized lighting control – including override of automatic function – is the the ability to counter-act shadow effects and the movement of natural light over the course of the day. This is difficult to accomplish with remotely mounted sensors, even when incorporated into general illumination products.
User control over their immediate area lighting provides greater user comfort and increased productivity from having light where and when it is needed. Further, in studies where user controls were well integrated, occupants tend to demand less than would be provided by general lighting controls schemes, resulting in greater energy savings. While measurement of productivity increases in response to lighting control is difficult to quantify, studies have shown reduction in lost days due to illness, reduced incident of nuisance headaches, and improvement in subjective feelings of well-being – when individuals find the lighting in their immediate work environment suits them.
Emerging control opportunities extend beyond on-off and dimming to include CCT selection and tuning to suit user preference. Another nascent technology provides adjustable spectral power distribution (SPD) content to support humancentric lighting – which includes elevating illuminance levels, as well as increase/decrease blue or red content based on time of day and potentially other influences. These are best managed at a personal level, controlled by the occupant, as application in general illumination cannot be tailored to individual needs (timing, personal response and preference). Further, providing the elevation of illumination levels required for effective physiological performance often conflicts with energy budgeting. Task level lighting can resolve this conflict.
Applying user-controlled products in work environments can be accomplished without connection to controls systems. However, integrating user-controlled lighting into building automation does offer advantages. Global master-off control, utilization of programming that utilizes furniture mounted indirect light in unoccupied spaces as part of the overall ambient lighting system, and monitoring user interface activities by collecting data from local sensors are just a few examples. For larger scale operations, the data collected presents unique opportunities to enhance the user lighting experience while potentially maximizing energy savings and use of space for the building operator.
A growing number of smart lighting products in furniture mount, portable and building mounted forms now incorporate user interfaces through portable devices – such as smart phones and dedicated remote controls – using a wireless or Bluetooth interface. This approach creates an intriguing opportunity to fully incorporate portable and furniture mounted lighting into the whole lighting system package, without hard wire integration.
While user control of lighting appears to be all positive, there are concerns worth addressing. While individuals tend to select illuminance levels lower than automatic global controls provide, which saves energy, too little light is as bad as too much. Further, selection of too-low CCTs may “feel” more comfortable, the impact is negative on visual performance factors. The result is that task performance, and feeling of general well-being can suffer, due to user selected settings counter-productive to their actual needs. For this reason, user-controlled lighting systems may need to include pre-set illuminance and CCT minimums based on task area. Monitoring of user-settings may also be necessary, making the case for inclusion into central controls systems even stronger.
The reduction of overhead lighting to providing minimal background illumination, augmented by individualized lighting systems incorporating user control, delivers optimal use of facilities resources and energy, while creating a more agreeable, and arguably healthier work environment. This approach can be applied equally well in manufacturing, commercial office, health care environments, and institutional support environments.
