Wireless technology is everywhere in our lives. There are more mobile phones in the world today than fixed-line telephones. More recently, short range wireless technologies, such as WiFi and Bluetooth, have allowed a huge variety of devices to communicate with each other. If we need a hands free kit for our mobile, often Bluetooth is the first choice. If we want to connect our computers in the home, wireless is the sensible option. Cables have their place but if we can do without cables, we benefit from much greater convenience and freedom.
So how have building services kept pace with advances in wireless communication? Within our sector, there has been an increase, albeit limited, in the number of devices operating wirelessly. These are typically employed to cover fire detection, lighting and basic HVAC control operations. However, two factors have traditionally counted against widespread adoption of wireless building control technology – the expense of such equipment and the reliability issues associated with wireless solutions when compared to an equivalent wired system. As a result, wireless controls have remained at the periphery of control applications, typically being chosen in preference to traditional alternatives only where installation is either difficult or cost prohibitive.
Given the low data rate signalling requirement in building control applications, why precisely have wireless control solutions under-achieved so badly? Electromagetic interference is one of the biggest issues. Electrically speaking, a modern commercial building is a very noisy place to be, generating considerable cable borne and airborne interference. The control gear in luminaires is, recognised as particularly, noisy in an electrical sense, and is perhaps the biggest culprit in typical offices due to their spatial density. Couple this with constantly altering office layouts and it can be seen that a modern building has been hostile to systems that cannot adapt to changing environments.
At Sontay, we recognise these issues but we also recognise the potential of wireless HVAC controls. Faster, easier and more cost effective installations, better control, reduced running costs and easier adaptation to the clients’ changing requirements. The reasoning for wireless controls is compelling.
New technology developments are set to help make wireless building control more affordable and far more reliable, having a positive impact on the way controls are selected and installed. At the same time, any wireless system must also be fully scalable to cope with building expansion and new control requirements over the lifetime of a building. They must be capable of quick and easy modification. Wireless is much easier and cheaper to upgrade compared to a wired system.
Most RF systems work by a transmitter sending a message to a receiver. If the message does not get through the system has no way of knowing that communication has failed. Reliable communication is achieved by increasing the transmitter power to overcome expected interference. Not a particularly elegant solution and one that can significantly affect the battery life. More complex systems use message acknowledgement. Here, when the transmitted message is received an acknowledgement is sent back to the transmitter. If no acknowledgement is received the transmitter sends the message again. This gives confidence in the receipt of the message but if the message is blocked by a permanent obstruction no amount of re-transmission will solve the problem. What is needed is a way of bypassing obstructions as well as interference. Reliability can be addressed by the innovative use of existing radio frequency techniques. Employing a mesh architecture allows this to happen.
Mesh is not so much a technology as a topology. It uses all the devices in the system as transceivers, a combined transmitter and receiver. Each device also intelligently routes messages to its neighbours. All messages are acknowledged and if a message fails to reach its destination the devices will automatically re-route via an alternative path. In this way, interference and physical obstructions are automatically bypassed by the mesh. Propagation of the signal is in a series of small hops, from device to device. This helps lower power requirements and conserve battery life. The co-operation of devices to relay messages gives the mesh system its self-healing property and combined with other sophisticated RF techniques gives this type of approach unrivalled resilience. It can also be optimised to suit the differing and demanding requirements of a specific control application.
Let us take an example of a typical speculative build office building.
During design, the likelihood is that the occupier’s requirements for HVAC control will not be known. Therefore a normal or best guess arrangement for the sensors and controls will be taken. With a wired system, the required cable management is installed, walls channelled, cables laid, devices fitted, system commissioned and décor finished. Once the occupier moves in the offices are rearranged. It is inevitable that during the partitioning process sensors will be removed, the cable plastered over and control goes out the window. During re-commissioning the loss of sensor is noted, the cable traced and re-installed. The client then discovers that the HVAC system is not as controllable as they require and additional sensors need to be fitted. Cabling needs to be run from the base station. Hopefully, this will be an easy task. Realistically, the work will need to be undertaken out of hours to minimise disruption, cables run in partitioning, perhaps new cable management, and likely making good. A few months later more cellular offices are erected. This could mean re-siting ventilation grills and the associated controls. The process begins again.
With a wireless system, the sensors can be fitted after decoration but before the occupier moves in. This minimises the likelihood of damage occurring and completely removes the risk of other trades damaging the cabling. The risk of clashing with other trades for the same space is eliminated, reducing wasted site time. Additionally, the sensors can be installed in the right location first time. With no cables dictating their positioning, the sensors can be placed for optimal control, reducing plant running costs. Reconfiguring or enhancing a wireless HVAC system involves no cabling, minimal disruption and is completed in a fraction of the normal time.
The market is demanding HVAC controls that are easier, quicker and more cost effective to install. Currently, most of the cost is in the physical installation of cables and as labour rates increase this will only aggravate the situation. RF systems have the potential to dramatically reduce the cost of installation by completely removing this physical cost. That’s why we believe wireless controls are the way forward. The benefits are hard to ignore for everyone in the distribution chain.