Planning for open systems
Given the potential benefits of the interoperability of building controls from different manufacturers, the Building Controls Industry Association offers guidance on its effective delivery.
Open protocols in building controls enable specifiers to mix and match products from different manufacturers on any given project. Clients have expressed a strong preference not to be locked into one particular manufacturer’s products, and open protocols give reassurance that products which are appropriate for their needs and budget and be used.
It is also increasingly common that building-services kit such as air-handling units includes an in-built control element. Also, clients are also looking to manage many elements of their building (or estate) through a single control system. This means that elements as diverse as lighting, security, cooling and energy monitoring must be brought under a single BMS. Open protocols enable these functions to be more easily integrated into the wider building-management system (BMS).
There are a number of open protocols on the market that enable devices from different controls manufacturers to operate successfully in one system. They include BACnet, LonWorks and KNX. Each protocol has its own features and benefits and so can be used according to the requirements of a particular building project.
Interoperability is now more readily achieved than ever before. The Building Controls Industry Association (BCIA) held a ‘ConnectFest’ at the end of 2009. A number of the leading UK controls manufacturers took part (Cylon Controls, Johnson Controls, Priva Building Intelligence, Siemens Building Technologies and Trend Controls). Their technical experts demonstrated that the multi-vendor approach is now entirely feasible.
However, while open systems offer a straightforward way for building controls experts to knit together a building-management system, pre-planning and preparation will help to ensure that the process of bringing together all the elements of a BMS runs as smoothly as possible. This is particularly the case when working on refurbishment projects, where legacy building-management systems have to be taken into account.
One of the most common problems which can arise on-site is that specified equipment is not designed to be compatible, but this problem can be avoided with checking at the early design stage. For example, the BACnet protocol (developed originally in the USA by ASHRAE but now widely adopted in Europe) requires that all devices conforming to the protocol have a PICS — a Protocol Implementation Conformance Statement.
A PICS is a written document, created by the manufacturer of a device, that identifies the particular options specified by BACnet which are implemented in the device. An important element of this document is an outline of the BIBBs (the BACnet Interoperability Building Blocks) that are supported by the device. By ensuring that the PICS and the BIBBs of controls devices from different suppliers match, the specifier can reduce compatibility issues on-site.
As more commercial buildings are undergoing refurbishment, particularly with the aim of making them more operationally energy efficient, the retrofitting of building-control systems is more common. Where this is the case, problems with time, space and cost can be avoided by ascertaining the type of cabling that is used in the building. Ethernet cabling issues mean that a building-management system becomes much more challenging and time-consuming to install.
For example, in theory, a BACnet system can be used on a building’s existing IT infrastructure. However, the IT department may have other thoughts — concerns about the amount of data being sent over the network, for example, or possible security issues. Also, shutting down the IT network for maintenance will have an adverse effect on the BMS. Again, forward planning and discussions with the clients can help to alleviate these problems before they arise.
As building-management systems offer a growing number of features and benefits, clients are increasingly interested in exploring the possibilities of a BMS. And with legislation putting pressure on clients to measure, monitor and manage energy use, a building-management system becomes a crucial business tool for complying with legislation and reducing energy costs.
As more is required of the BMS, greater forward-planning is necessary. Early involvement of building-controls specialists will help the installation of a new or retrofitted BMS. With a greater understanding of the building’s requirements, and those of the end-user, the controls specialist can maximise the BMS performance.
*Building Controls Industry Association.
