The rise of building management systems has spawned the need for a fast, reliable way for buildings to feed information back to those systems.
Wireless sensor technologies are widely available for this purpose. The reduction in installation and maintenance costs makes them a hugely appealing option.
It is vital, therefore, to choose the right wireless solution. The key is to understand that wireless does not necessarily mean cable-less. While adding a layer of complexity to the debate – not least when it comes to terminology – this should inform consulting engineers and installers as to which is the best option for the job at hand.
The two main choices in the wireless sensor market are: a truly wireless solution whose sensors are powered by the energy in their environment, such as photovoltaic; or those that, although wireless in the way they communicate, require a constant power supply via cabling.
The cable-less, wireless sensors sleep most of the time. When the temperature or whatever value they are sensing changes it wakes the device, which then transmits the new value to a receiver.
The wireless but cabled sensors operate more like a mobile phone network, where the sensors constantly communicate with neighbouring sensors and to a receiver. Because this type of sensor is constantly sending and receiving information, it needs to be constantly powered – and that is the difference. It needs a cable.
There are numerous pros and cons for each type of system. But ultimately, sensors that require constant power will need cabling, which effectively means that they lose the advantages of the “wireless” approach such as lower installation costs. After all, installing two cores is no different to running three cores for a conventional sensor. Other considerations for the truly wireless route are where the architect wants to avoid unsightly cabling and containment.
You really need to be truly wireless to take full advantage of the cost savings.
With the Enocean technology, there are numerous manufacturers out there doing complimentary products – good news for installers as they are truly compatible and you are able to mix and match between manufacturers.
Malcolm Anson is managing director at Clarkson Controls