Opening the way to efficiency
Any building designer, owner or operator striving to achieve energy efficiency must put building controls at the heart of the programme. Ian Ellis, President of the BCIA explains how open protocol systems are making this easier than ever before.
Open systems protocols for building controls are probably not high on the list of interests for even the most dedicated building energy manager. However, the development and evolution of protocols such as LonWorks, BACnet, Modbus, Mbus, KNX and others has had a significant impact on how building energy use can be monitored, measured and managed. Moreover, this applies to new-build projects as well as refurbishment of existing commercial buildings.
The development of open systems, and the move away from manufacturer-written protocols, has created a much more open market for controls. Specifiers and end-users can now select the controls they want to use – even using a variety on one project if they can see a benefit. Clients need no longer feel that they are locked into a single supplier.
One of the major benefits of this is that buildings can be more easily future-proofed. Building controls are constantly developing, and open protocols mean that a building owner can take advantage of new controls technologies without having to completely remove an existing system and start again. From an energy efficiency point of view this is vital because building services equipment such as boilers, air handling units and lighting are all achieving ever-higher efficiency levels.
Open systems such as BACnet or LonWorks allow controls installers to incorporate that equipment more easily. There is an increasing amount of packaged building services plant that includes manufacturer-incorporated controls. Before open systems became so prevalent, a proprietary interface would have been necessary – and that would have been far more time consuming for the systems installer.
Open systems create a much more efficient platform for integrating services into a building management system. In the days when a chiller or boiler had its own proprietary controls, the controls engineer would have had to disable those and creating the need for ‘double engineering’ which wasted time and money.
As more energy managers are looking to find cost-effective ways to reduce energy waste in their buildings, the ability to upgrade equipment is increasingly important. But in today’s economic climate, a whole-system or whole-building approach is not financially viable. With open systems, it is possible to migrate gradually to new controls and other new services kit, taking a step-by-step approach.
It is also possible to add extra energy efficiency measures to a system’s existing sensor array. For example, a lighting system may use PIR sensors for occupancy detection. Open protocols such as BACnet allow this sensor to be linked to local fan coils so that cooling as well as lighting is used only when required, with extra energy efficiency benefits. There are further benefits when the existing head-end for the building management system can be retained as new equipment and features are added, reducing the cost of new energy efficiency measures.
By taking a staged approach to energy efficiency by building on an existing open protocol, it is possible to demonstrate the financial benefits of energy efficiency measures – and perhaps use these savings for further investment in an efficiency programme.
However, while open systems are certainly enabling wider and better application of building controls there are a number of do’s and don’ts that apply when thinking about adding to or refurbishing your existing building controls.
The BCIA has recently held a number of events for its members to demonstrate open systems in action. Members created a ‘live’ building management system, working on a number of different protocols including BACnet, Modbus, KNX and LonWorks among others. The demonstration highlighted the fact that interoperability is certainly achievable, but a certain amount of pre-planning helps to smooth the process.
For example, with refurbishment projects, there are some physical considerations that have to be borne in mind. Older buildings may have wiring that is not compatible with today’s IT requirements and so re-wiring, with its attendant extra costs, may be necessary.
The age of the existing system is also a factor that will impact on how far open systems can be employed. For example, a protocol such as BACnet has evolved over a number of years, which means that there is extra work involved in linking the ‘old’ BACnet products to a new system.
Another important point to note is that today’s building management systems can run on the same network as a building’s IT system. For example, data gathered from the BMS can be hosted on by the client’s IT administrator, saving the cost of extra data storage facilities. But close liaison with the client’s IT management is vital to ensure that this objective is achieved without causing problems further down the line.
However, none of these issues is insurmountable. Forward planning and early discussions with controls consultants can ensure that such challenges are identified, costed and solved early.
The BCIA is keen to encourage end-users not to regard protocols as a black art, to be considered only by controls engineers. These protocols are tools that are enabling our experts to deliver better service and to help building operators to achieve greater building energy efficiencies. By understanding the part that open systems play, we hope that clients will get controls experts involved in their efficiency programmes much earlier.
Types of protocol
BACnet: Developed by ASHRAE (the American Society of Heating, Refrigeration and Air Conditioning Engineers), starting in 1987, and is now an ISO standard protocol. It was designed specifically for the automation and control of building services equipment including heating, ventilation, lighting and fire detection. Although it began life in the USA, BACnet has been widely adopted across Europe and in the UK.
LonWorks: Another protocol with its routes in the US, this was developed by the Echelon Corporation for networking devices over twisted pair, powerlines and fibre optics. Again, it was devised for the automation of building services equipment such as hvac and lighting.
Modbus: a communications protocol developed in the late 1970s, for use with programmable logic controllers (PLCs – an early form of digital control for building services).
M-Bus or Meter Bus: a European standard for the remote reading or gas or electricity meters. It can also be used for other utilities such as water. The M-Bus standard was developed to aid the networking and remote reading of meters in homes and commercial buildings.
KNX: Is a standard originally designed for use in homes, but is now widely applied in commercial buildings. KNX represents the convergence of three previous standards and is now administered by the KNX Association.
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