Smart Lighting owns the ceiling – but what about the walls?
The transition from traditional lighting to LED lighting has triggered a wave of innovation that will establish lighting as an Internet of Things (IoT) backbone in the building. High node density coupled with readily available power supply make lighting fixtures ideal nodes of a connected wireless mesh network. Self-powered sensors play a key role to balance costs and benefits for maximized efficiency.
Such an IoT network will transport information about the fixtures status but also about vital building parameters generated by connected sensors. This combination of smart LED lighting with sensors integrated into an IoT network is often referred to as the “Smart Ceiling”.
The “Smart Wall”
Reducing the sensor and network infrastructure to a smart ceiling however misses one key part – the walls of the building together with the sensors and controls that have to be placed there. While the ceiling is ideal for placing occupancy or light level sensors, it is usually much less suited for temperature and air quality sensors and not at all for user interfaces such as thermostats or light switches.
Therefore even the smartest building will typically require certain device types to be placed onto the wall from where they will communicate with the network in the ceiling. This is also a key factor for building owners who want to tap the full potential of intelligent control. Depending on the specific usage situation, studies quote energy savings that range from 10% to more than 50% implementing lighting control mechanisms such as daylighting or occupancy-based room management.*
The key question however becomes how to connect and power such devices.
Three options are possible for that:
- Wired connection
This is the classical way of connecting devices with each other and is still used today in many systems such as KNX. Relying on a wired connection however reduces or even eliminates the flexibility benefit offered by wireless systems. Every redesign of a building that affects those devices will result in a need for rewiring which is undesirable both from effort and down time perspective. Moreover, increasing the amount of wiring in the walls will strongly reduce the option of pre-fabrication and pre-installation ahead of the actual construction.
- Wireless connection powered by batteries
Having a wireless network in the ceiling makes using wireless devices on the wall a logical extension. The communication distance to the next node in the ceiling network is typically very low and the communication therefore reliable. Wireless systems provide significantly higher flexibility than their wired counterparts and can be installed or extended much quicker.
Power to the wireless devices can be supplied by batteries which usually promise a runtime of several years, theoretically. The rise of new business models such as Lighting as a Service (LaaS) however means that the responsibility for operation shifts from the building owner to the company installing the lighting network. Therefore total cost of ownership and maintenance cost become critical factors that determine the profitability of each installation.
Maintenance events – and especially unplanned maintenance due to battery failure – typically result in significant cost for maintenance personal and possibly compensation for customer down time.
- Wireless connection powered by energy harvesting
Energy harvesting wireless devices generate all energy required for their operation from their environment. The most obvious example is the energy harvesting wireless switch that generates its energy from the kinetic movement of being pressed. Other sources used for self-powered sensors are light (indoor and outdoor) or temperature differences.
Energy harvesting devices by their nature do not require maintenance and can therefore have a positive impact on total cost. It also gives installations with energy saving purposes an eco-friendly character by avoiding tons of battery waste or cables containing resource consuming materials such as copper, steel, plastics etc. Based on the EnOcean standard (ISO/IEC 14543-3-1X), there is a large interoperable ecosystem of products available. Self-powered solutions can also communicate via Bluetooth® or Zigbee.
The Retrofit Reality
Lighting controls are increasingly becoming standard in new construction of office buildings, but this accounts only for a small fraction of the total number of buildings.
Europe contains some 160 million buildings as estimated by experts of the ECTP/E2BA.** More than 80% of these buildings are older than 30 years and only approximately 1% are newly built each year.
From these numbers it is clear that major lighting energy savings can only be realized by retrofitting the existing building stock. To successfully address this market, lighting controls must present a positive ratio between the cost spent for the upgrade of the lighting system and the realized gains.
The main factors affecting cost are the cost of the products themselves, the cost of installation and the cost of operation (including maintenance). The latter two factors can be significantly lowered by the use of a wireless control system (providing quick installation with minimal disruption) in conjunction with maintenance-free energy harvesting sensors.
The Battery-free Approach
The wide range of established energy harvesting wireless products enabled by the EnOcean technology allows for a complete wireless LED control system for retrofit projects. Different scenarios of smart lighting control can be set up quite easily at low installation costs and only require a minimum of maintenance. Additionally, building operators can expand the system at any time with additional sensors for an overall approach of intelligent data usage to achieve immediate energy savings, increased comfort with low investments and a fast return on investment (ROI).
Thanks to the highly flexible installation of wireless sensors and switches, smart lighting now owns the ceiling and the walls. The devices’ self-powered operation even eliminates the need for changing batteries. Another plus for a positive ratio between the cost spent and the achieved outcomes. Thus, the IoT-enabled digital transition with all its benefits of a demand-based smart control can become reality for all buildings – whether newly built or existing. (See also The Iot Pie Blog – Smart Buildings)
You want to learn more about energy harvesting wireless control? Meet EnOcean at Trends in Lighting Event – TiL 2018, Bregenz, Austria (Sep. 25-27) www.trends.lighting/.
*Source: US Department of Energy: Wireless Sensors for Lighting Energy Savings https://www.energy.gov/sites/prod/files/2017/01/f34/wireless_occupancy_sensor_guide.pdf
**Source: European Construction Technology Platform: “Energy Efficient Buildings European Initiative” written by E2BA