Lighting motion sensors were once about convenience and now more and more they have become part of an energy management strategy for minimising lighting power consumption. They now feature prominently in the building code as a mandatory fixture in commercial building design. In many new office constructions, sensors often outnumber light switches, so we are relying on them increasingly as the primary form of control for room lighting. It could be argued that expanded thought should go into sensor selection, placement and programming to improve functionality and achieve the biggest energy savings.
There is certainly a wider range of stand-alone sensors for buildings these days. They commonly switch a local 240V load or a small group of localised DALI controlled light fittings. They typically have just one timer function set only once when they are installed. They are highly effective in small spaces and can be a great tool. There are also options with master and slave sensors working together to expand coverage beyond a single detection zone. There is a point though, when we expect more of what they can deliver. That’s where smart network lighting controlled sensors really take things to the next level.
Network Lighting Control Sensors
Often when people think of sensors and energy savings, they only think of the kilowatt hours related to lighting power that the sensor can save. If our imagination or design viewpoint is limited to this thinking, often a huge opportunity for significant energy cost reduction can be missed, particularly in large buildings.
Network lighting control systems are highly intelligent and provide far more functionality and benefits when compared to stand-alone sensors. With an intelligent lighting control system, the lighting’s load controllers, sensors, intelligent lighting control panels and a range of building services connect and communicate with each other to create multiple layers of monitoring, automation and user control. The role networked sensors play in these applications is greatly enhanced when compared to stand-alone sensors.
Sensors in the real world
Imagine a multi-story office complex – The first person who comes in arrives three hours before general working hours. With basic stand-alone sensors the person may walk through a few floors triggering hundreds of lights for 20 min just to get their coffee and go to their desk. With an intelligent lighting control system using integrated sensors, most of the lights may only be triggered for a few minutes in this scenario because of the ‘time of day’ or by high level feedback between the security system and the lighting control system which determines that this is not normal occupancy for the building. Business hours are more dynamic these days and there is a point where basic sensors fall short of the mark.
Integrating sensors with heating and cooling
If we take that intelligence a step further, imagine the impact on a 5 or 10 story office tower if the sensors could also report to the building management system (BMS). The networked sensors can determine which rooms are occupied and which rooms are not across the day, which results in the heating and cooling being placed into their most energy efficient standby mode for all of the unoccupied spaces.
With heating and cooling being around 40% of the energy consumption in an office building, suddenly integrated lighting sensors monitoring the space can become an enormous energy reduction tool when communicating with a building management system over the life of the building. Network lighting control sensors can provide a high level of feedback to the building management system to optimize heating and cooling demand and create tighter energy efficiencies in lighting.
Integrating sensors with a building’s normal and after business hours
Using intelligent network controlled sensors does not limit the huge savings to just BMS integration. By fine tuning the absence detection times by time of day, network sensors greatly extend the life expectancy of the building’s lighting fixtures, because stand-alone sensors are limited to one ‘time-off’ setting. Network controlled sensors allow you to have the best detection times for normal work hours, shoulder times and even special activation for cleaners or security staff when integrated with other building systems. If you have ever driven through the city at night, the office buildings showing a large lighting use after closing time clearly highlight the problems poor lighting control design can create, especially to the bottom line.
Network lighting control systems create more opportunities for smart sensor functionality. If a person is working back late at night on their own, they may not feel great being alone in the dark with only one light on. Network lighting control systems can provide a balance providing adjacent corridor lighting at an energy efficient level while a lone office is occupied after hours.
In sports stadiums they can keep high energy lighting on, only in the areas where there is activity. So during practice times when one of three courts is being used, two are dimmed for energy efficiency but allow casual traffic through the area. But during a competition period, the sensors work differently to maintain brighter levels.
Sensors in meeting and presentation rooms
Many buildings have dimmable lighting especially in presentation and meeting areas. They can have high and low levels of occupancy and dimming considerations that only smart sensors can manage. For example if a meeting requires a particular level of dimming for the presentation, smarter network connected sensors work with the dimming technology to maintain the precise dimming levels selected for the presentation. During breaks, the lights turn off once absence is detected and when the meeting recommences, the sensors send the dimming levels back to the previous settings ready to continue if the light switches have not been used.
Sensors in open plan offices
Open plan offices can be tricky spaces for motion sensors. Activity can be minimal with people being desk bound for long periods. Smart network lighting control sensors can work in groups to monitor larger areas of motion to keep an open plan office on in a predictable way. Sensors installed beside windows can monitor the ambient light and automatically dim lights when ample sunlight streams into the room or condition change with the state of block out and sheer blinds. When the sun dips behind clouds the sensors are smart enough to create smooth transitions in light to avoid flashing of lights when the environment changes creating a more comfortable space to work and concentrate in. During ‘afterhours’, having received feedback from a system time clock, the sensors can work in a more localised fashion for cleaners without the need to keep all open plan area lights on.
Considering your choice of sensors
So when we think of sensors and building codes, we need to think more about the space, the user experience, the long term energy efficiencies and ensuring the overall solution transfers right through from design concept to implementation and programming that is specific to the occupants’ needs in any building.
There are many instances where using simple stand-alone sensors can be a huge missed opportunity when considering all of the long term energy cost savings and application possibilities.
View Lightmoves’ range of intelligent sensors here.