Take a long-term view on integration
Graham Lewry of Trend Controls answers readers’ questions about integrating the various devices that comprise a building energy management system (BEMS).
Q Why is the correct integration of the component parts of a BEMS so important?
A Integrating disparate control systems or devices into a BEMS — whether a natural-ventilation system or a standalone air-conditioning unit with its own controls — is imperative to achieve the complete energy optimisation of a building’s infrastructure. Up to 84% of a building’s energy usage can be under the control of a BEMS, so the seamless integration of its component parts will ensure that it performs at its optimum.
However, this process must be carried out correctly — with a view to long-term practicality. It is imperative the devices are not selected in isolation but with the complete building operation in mind. Integrating disparate devices into the system must also be recognised as a specific activity and the appropriate costs allocated. If this is not managed correctly, the solution will offer little in the way of effective monitoring and management of a building’s energy usage!
Q I’ve been told to avoid using components from different manufacturers whenever and wherever possible. Is this just scaremongering or simply good advice?
A It depends on the objectives. Are you looking to connect two disparate control systems, such as a VRF system and perimeter-heating circuit, or are you looking to combine the cheapest component parts of various BMS control systems or independent field device monitoring items to create a low-purchase-cost BEMS system?
If you want to connect two disparate systems, then using different manufacturer’s products provides a workable solution as long as the role of integration is considered part of the project. However, in the case of the latter objective, our experience is that a single manufacturer’s products provide by far the most robust solution.
Their diverse products will have been specifically designed to work as a system, with engineers who are trained and familiar with the complete system and how the component parts work together. This ensures quick, easy and seamless integration of, for example, the communications between the terminal unit and main plant controllers and I/O modules. Additionally, any savings made on purchase price by seeking a low-cost hardware solution will quickly be lost when looking at engineering time to ensure the component parts work seamlessly together.
Q Does using a single supplier mean that I’ll be ‘locked in’ to using its products?
A Certainly not. In fact, this is one of the most common misconceptions about companies that promote a single supplier solution.
This probably stemmed from the early days of BEMS when building managers had to commit long-term to a certain manufacturer and/or protocol. This ‘captive audience’ meant that prices for new components could be artificially inflated, as the only alternative would be to rip everything out and start again.
Nowadays nothing could be further from the truth. For example, Trend Controls offers all of its equipment through a network of over 450 independent partners in over 50 countries, and customers are free to work with any partner or, indeed, any system they choose.
Q Third-party products are generally less expensive than those from the manufacturer of my BEMS. Is there any problem with using them?
A In theory it should not be a problem and, indeed, some ‘off-the-shelf’ or mass-produced items are less expensive initially. However, using third-party products could cost more in the long-term. For example, should something go wrong with a third-party device and a chosen installation and maintenance partner is not familiar with it or unable to remedy the problem, it could mean that specialist — and for that read expensive — assistance may be required. This can quickly negate any financial advantage gained on the initial price.
Also, backwards compatibility must be a consideration. Someone who purchased a BEMS from a particular manufacturer some time ago and now wishes to upgrade or expand their system will, in the vast majority of cases, be able to install new devices from the same company that will communicate seamlessly with earlier products. Scalability is important too. If disparate devices have been used to create a system, extensions in the future might present challenges to the original infrastructure.
Q What should I do if there is no alternative to using a third-party component?
A Flexibility is sometimes necessary, as manufacturers rarely make all the products that need to be integrated. For example, it is important for items such as utility meters, which provide a baseline for ongoing energy management, to be assimilated in order to correctly gauge overall energy use.
In these cases, specially designed ‘nodes’ enable a BEMS to interface with diverse protocols such as BACnet, ModBUS, MBUS and LonWorks. State-of-the-art software applications allow values from third-party products to be included in schematic pages so that users can monitor them and make adjustments wherever necessary.
It is also worth remembering that while the technology used is obviously important, a cohesive and strategic approach to BEMS integration will pay dividends, ensuring the role of integrating a third-party device is identified and specified correctly. This relies on technology providers, integration experts and building managers working collaboratively to ensure that performance is optimised.
Graham Lewry is with Trend Controls.