Complementing the BMS for greater cost savings

Introducing additional measures to fine-tune boiler performance, over and above those achieved by a BMS, can yield as much as 25% extra energy savings.

Sabien Technology’s experience over 70 projects in the last five years has shown unequivocally that the standard configuration for a building management system (BMS) or building energy management system (BEMS) does not address the issue of dry cycling

Unsurprisingly, many people expect that their BMS or BEMS will take care of boiler dry cycling, where the boiler fires to compensate for standing heat losses, resulting in unnecessary fuel consumption. The reality, however, is that the key role of a BMS is to optimise the whole building through the building services systems it controls. This is achieved by ‘looking at’ each system as a whole rather than the performance of the individual plant items.

In the case of boilers, a BMS or BEMS monitors and responds to blended flow and return temperatures from all the boilers; so unless there’s only one boiler the BMS gets an overview, rather than a detailed picture for each boiler as the heating loads vary.

The fact that the BMS doesn’t ‘see’ this is also why many building operators are unaware that dry cycling is occurring – and it’s the reason why dry cycling isn’t included amongst the standard control strategies that are included in the majority of BMSs.

This was the situation at the headquarters of facilities management provider Serco, where Sabien’s M2G boiler load optimiser was used to address dry cycling issues. “Many people think building energy management systems can control every aspect of a boiler’s operation but this is not the case. The M2G interfaced very smoothly with our BEMS and the two systems now complement each other to maximise energy savings” explained Alan Taylor, Serco’s Technical Manager for Government Integrated Services.

Of course, it is technically possible to re-programme a BMS to include dry cycling, but this is a time-consuming process that eats up expensive programmer time (we’ve heard of estimates as high as 18 months). It also necessitates additional sensors and, quite possibly, upgrading of the boiler room outstation.

In fact, when managing agents Jones Lang LaSalle (JLL) discovered dry cycling problems at some of their customers’ premises, re-programming the BMS was their initial consideration. Mark Bottriell, JLL’s Portfolio Energy Manager for Europe, Middle East and Africa explained: “In one case the BMS is very sophisticated and it would have been technically possible to have a special program written to control the dry cycling, but it was more time-effective to use an off-the-shelf product, which has potential to integrate fully with the existing BMS, particularly when contemplating new programming requirements.”

So if the cost of re-programming the BMS is prohibitive, it makes sense to use a retrofit solution that will deal with dry cycling and work with the BMS and other controls. Using validation techniques that have been independently verified, Sabien’s M2G has been proven to provide typical fuel savings of between 10% and 25%, with payback periods consistently delivered under 2 years.

To find out how Sabien's M2G addresses the problem of dry cycling click here

For client case studies please click here