Delivering a BMS that performs

The inclusion of a procedure in a new ISO/EN standard for specifying the functional requirements of a building-automation and control system will, believes KEITH CHURCHES, lead to better systems.Readers may remember a flurry of activity that started over 10 years ago which was initiated by the release of the Construction Products Directive. Since then, a CEN technical committee (TC247) has produced a range of standards that became public a few years ago. Now, more detailed standards are about to be released. The publications offer a range of seven documents known as ISO/EN 16484 ‘Building automation and control systems’ (BACS). Before continuing, I need to clear up the question ‘when is a BMS a BACS?’. Here is the Energy Directive’s definition: ‘If a building control system, building management system, or building energy management system complies with the requirements of all the EN ISO 16484 standards then it should be designated as a building automation and control system (BACS)’. The past two years has seen additional reformatting work completed by the same groups to mould these standards into a form acceptable to the International Standards Organisation (ISO). The seven parts cover the areas detailed in Table 1 at the end of this article. Consultant support The way projects for building-management systems are specified and implemented could potentially be changed by Part 3 ‘Functions’ in this table. I say potentially, because the processes need to be adopted on a national basis and, in particular, taken up by consultants in the industry. German consultants, for example, have been using the ‘Function List’ as defined in Part 3 for over 10 years in a DIN Standard form. They also go one stage further, using this process to estimate the cost of implementing a BMS. The Function List is based on a spreadsheet where each row defines an item of equipment within the plant and each column is used for a defined function, such as an input, output, delay, counter, binary logic block, energy-saving feature etc. Fig. 1 shows a section of the Function List, which in its entirety consists of 48 function columns.
Fig. 1: The function list for defining the specification of a building-management system comprises, in total, 48 columns.
The structure of this table allows additional sections to be added, either by manufacturers or by national bodies. For example, there are many more applications related to electric heating in France, so the French are expected to create additional functions associated to this activity and republish the standard on a national basis. Each function is detailed in the form of a process block (Table), which is also accompanied by explanatory text. This methodology is borrowed from the process industry, where standardisation and accountability has been more essential in the past. Where appropriate, these descriptions are enhanced by a graphical transformation (Input/Output) graph (Fig. 2).
Fig. 2: Function blocks compiled as spreadsheets can be represented graphically. This example is for a sliding setpoint function.
The user of the process then adds items of plant equipment into the row headers (see left-hand column of Function List in Fig. 1), then the quantity into the associated cell (shown to the right of each row header). The benefit of this approach is to move closer to an unambiguous methodology describing the functional deliverables within a BACS solution, which in turn should lead to fewer variances during handover. This approach should prove particularly valuable when third-party systems are involved, where Part 7 (Project Implementation) will seek to use a different form of the Function List. This table will define all the data flows between systems, with the data attributes fully defined. Smart tools: There are programs available that will automatically generate AutoCad drawings using the Function List as input — and vice versa, with an HVAC plant drawing producing the Function List. To date, the only offering is a German product that can be viewed at the main distributor’s site at [www.mervisoft.de]. A hyperlink offers an English environment and demonstration version that can be downloaded. Representation: Most BACS manufacturers have been represented on the CEN and ISO committees. It is therefore likely that the future product offerings will provide products and systems that comply and smart tools that close the gap between specification and implementation. The net result will be higher-quality BACS systems and an industry with greater coherence. The UK view within Europe has been supported and shadowed by the British Standards Institution in the form of a committee (RHE16) that has many representatives from the Building Controls Industry Association. Keith Churches is a member of the Building Controls Industry Association, PO Box 872, Chippenham, Wilts SN15 5WA. He is a convenor of the CEN Technical Committee TC247 behind the development of ISO/EN16484.
BCIA table
Table 1. The seven parts of ISO/EN16484 cover the specification and installation of a building-automation and control system.



modbs tv logo

New Sustainability Director for Wates Group

Wates Group, a family-owned development, building and property maintenance company, has appointed Cressida Curtis as its new Group Sustainability Director.

Domus Ventilation appoints new contractor sales managers

Ventilation systems manufacturer Domus Ventilation has announced the arrival of three new Contractor Sales Managers.