Focus: Smart Lighting
Lighting is no longer just about light, but also information – key to the modern museum experience, says Roger Sexton
The quality of light in an art gallery or museum is fundamental. It affects not only how the artwork or artefact is viewed, but the perception of the gallery’s architecture and visitors’ sense of themselves in the space. The factors that determine light quality include the colour consistency of the source and its ability to render colours as realistically as possible, largely a function of the LEDs and phosphors used in the light source. But the quality of dimming is also important, in terms of its smoothness, its depth and its lack of flicker, including non-visible flicker, which may be linked to negative physiological effects it has been claimed. In gallery applications, colour-point stability through the dimming cycle is also important.
One way of ensuring good-quality dimming is to have the LED driver and dimming circuitry incorporated into a smart LED module. Perfect tuning of modulation and frequency is then ensured. These modules can incorporate diagnostic sensors that detect temperature, power status and more, allowing a microprocessor to report the status of the module in real time, as well as protect the module from itself.
Dimming can be automatically triggered, for instance, if the module begins to overheat due to a site-related issue. But what opens up a whole range of new possibilities is the addition of wireless communication. This is about forming a seamless network of intelligent, interoperable devices. Intelligence allows these smart modules to make independent decisions based on direct, real-time input from sensors and switches, without the delays and inconsistencies associated with centralised controllers.
The use of simple, intuitive apps demystifies controls, allowing anyone to carry out commissioning and operation. Commissioning can be as easy as selecting a given track spot on a handheld phone or tablet and setting the level with a virtual slider. Groups and presets can be created by ‘dragging and dropping’. And when the exhibition is changed the process is simply repeated – no wires or controllers to worry about. Move the luminaires, and the rest is all software. There are no driver boxes and all the action is below, not in or above, the ceiling.
Smart LED modules can save initial cost on drivers, dedicated control wiring and hubs. But they can also provide significant savings on maintenance costs. Module self-monitoring and auto-correction can prolong module life and real-time reporting of operational information makes preventative maintenance possible.
Maintenance is especially important if downtime is costly or high ceilings necessitate scissor lifts. Think of the high-vaulted Victorian ceilings in some UK museums, or where closely spaced exhibits are threatened by a cherry-picker’s turning radius.
With continuous, accurate diagnostics, maintenance people only need to go on site once, knowing in advance what the problem is. And they bring the right parts with them. Smart modules can also be central to energy saving.
Having an LED driver and dimming circuitry incorporated into a smart LED module can ensure good-quality dimming
Lux sensors linked wirelessly to them can detect incoming daylight and trigger a decrease or increase in the artificial lighting. While daylight compensation has been available for decades, wireless sensing and independent control makes it more flexible and more powerful. The modules can be programmed to prevent irritating changes based on transient conditions, for example. The same can be said for motion sensors. Programmable occupancy and lighting states, with configurable delays and ramp times, can provide efficient, adaptive control to individual visitors, while preventing abrupt changes that could mar a visitor’s experience.
Sensor-controlled lighting can be a major aid to conservation. In galleries, there is a balancing act between access and conservation. For conservators, light is a menace – all light degrades paintings over time. One advantage of LEDs is that they do not emit ultraviolet radiation, which causes pigments in some paints and fabrics to fade or change hue.
But exposure to visible light does have a photochemical effect, and in planning an exhibit the conservator has to calculate a maximum allowable light dose. This takes into account the artwork’s sensitivity, the light-source damage factor, and the work’s preservation target – the time before a ‘just noticeable difference’ is evident. Sensors can measure lux-hour exposure on a painting, providing data that is digested by specialised software into practical advice, warnings, and alarms.
The same modules can emit periodic Eddystone or iBeacons (communication protocols) that allow a mobile app to identify the visitor’s location in the museum for a variety of purposes. Until now beacons have been standalone, plastic, battery-powered devices that trade off transmission frequency and power against the maintenance hassle of battery replacement. Smart LED modules allow optimum beacon configuration for more accurate location, while eliminating battery maintenance.
The signal from Global Positioning Systems (GPS), which enables car navigation and speeds up delivery of emergency services, does not enter buildings; and even if it did, it would not be accurate enough for an interior. For indoor use, for example, knowing which floor of a building someone is on rather than just a point on a map is important. Museum visitors would like to know which picture they are close to with an accuracy of less than a metre, so that they can be provided with information about it. Beacons advertise proximity-specific data up to 100 times a second, for another bluetooth device to pick up. A mobile app compares the received signal strengths from different beacons, locating the user and calling up information suitable to that location, whether it is details of an exhibit or indoor mapping.
This information can supplement wall plaques, for example, and provide up-to-the-minute links to events, dates or other temporary exhibits. Wayfinding can guide users on a preconfigured tour or to related exhibits, suggest an appropriate route to the nearest bathroom or point them to the museum cafe or shop. It’s in this area of enhancing the visitor’s experience that perhaps some of the more exciting possibilities lie.
A lone user in a gallery may not even notice that as they approach a given painting the lighting has slowly been increasing in their direction of travel. Visitors can start off in a cocoon of light that gradually expands. Reach point A, then lighting at point B comes on as guidance. Lighting can be increased slowly as the visitor reaches a statue to create a revelation. This is not simply aiding the journey – lighting becomes part of the show.
Case Study
Museon, The Hague
Lighting with built-in intelligence and the ability to communicate is helping a Dutch museum improve the visitor experience while conserving energy.
Located in the Hague, Museon is a museum for culture and science whose focus is the relationship between humankind, nature and society. In October 2016, it opened a new permanent exhibition called One Planet, designed to promote the fair distribution of food, water and energy globally, and the acceptance of differences in cultural identity.
The current building, designed by Wim Quist, dates from 1985 and sits next to Hendrik Petrus Berlage’s Municipal Museum, completed in 1935. Its interior has an airy feel, with voids around nested squares so that visitors never have the impression of being enclosed. Every room has a view of a larger part of the exhibition.
But Jeroen Pijl, responsible for exhibition lighting at the museum, felt that the fluorescent and halogen lighting previously used throughout had a ‘soporific’ effect on visitors, so the lighting on the second floor, which houses One Planet, has been refurbished, the new lighting design, carried out by Licht Joost de Beij, includes nearly 400 track spots mounted in display cabinets and at ceiling level, with ceiling and floormounted wallwashing around all columns. A suspended band of colour-changing lighting snakes its way around the whole exhibition.
The museum of culture and science in The Hague, Museon has been installed with intelligent lighting. Image Credit: Mike Bink
Joost de Beij’s brief was to emphasise the museum’s architecture, to make navigation easier and to maximise the feeling of wellbeing among visitors. The aim was not only to improve the lighting design and provide better lighting control, but also to create the backbone infrastructure for future Internet of Things connectivity.
The new lighting includes 380 Mike Stoane spotlights on 48V tracks, which replaced conventional 230V AC track. Using DC track has enabled the Museon to power multiple fixtures from a single AC-DC power supply, eliminate external driver boxes, separate controllers and control wires, and thus gain flexibility in configuring and reconfiguring its lighting.
The luminaires incorporate Xicato 3000K Artist intelligent LED modules, which integrate bluetooth wireless control and beacons. A Bluetooth Low Energy (BLE) board in the modules communicates with mobile devices such as smartphones and tablets to create multiple, secure networks with a virtually unlimited number of lights, sensors or switches. This simplifies the commissioning of lights and lighting groups, scene creation (for cleaning or service modes, for example) and output settings for each fixture and exhibit.
LED sources have greater longevity than traditional sources, but the LED modules also protect themselves, and provide operational data that can be used to monitor conditions that affect their lifetime. These particular modules include an Integrated Diagnostics Engine that takes temperature and electrical measurements to improve both running and preventative maintenance. A next step will be to add BLE occupancy and daylight sensors that communicate with the lighting for additional energy savings.
The switch to LED lighting and dimming control has already helped Museon meet a CO2 reduction target of 200 tonnes a year, a condition of funding that came from the Klimaatfonds-Duurzaam Den Haag. Energy consumption fell from 13.7 kW/hr to 4.85 kW/hr and the museum anticipates further improvements through the addition of sensors and programming.
Joost de Beij will also explore ways to enhance the visitor experience with sensor-driven interactivity and dynamic lighting. For example, Museon plans to use the lighting’s bluetooth capability to provide personal tours, using beacon-based proximity awareness and content.
