Going the extra mile by Tony Willis

Industry comment

Published: 26 July

Type: Industry comment

Year: 2016

It may be summer now but the next heating season will soon be with us, so this is a good time to consider added measures that will optimise the energy performance boilers to reduce costs and carbon emissions.

By now, many organisations have already implemented some measures to improve the efficiency of their building(s)’ heating and hot water systems. These might have included optimising or upgrading the building management system (BMS), adjusting temperature settings, introducing boiler sequencing and weather compensation (if they weren’t already in place) and encouraging behavioural changes.

Nevertheless, there is sustained pressure to ‘go the extra mile’ and achieve further savings once these obvious ‘tweaks’ have been applied. The challenge for the energy manager, therefore, is to identify additional opportunities for achieving significant savings within budgetary constraints.

In this respect, those projects that will deliver a fast payback for a relatively small investment of capital have particular appeal, as the savings achieved help to fund more ambitious, longer-term energy saving projects. In many cases such projects will involve retrofitting additional technologies to enhance any energy savings that are already being achieved.

With respect to boiler plant, the next obvious area to address is that of boiler dry cycling, something with which many Energyst readers will already be familiar. What may not be quite so obvious is the fact that the existing energy-saving measures mentioned above will not typically identify or prevent boiler dry cycling directly. Yet tackling this phenomenon – using patented Sabien M2G retrofit boiler load optimisation – has the potential to reduce energy consumption by 12% to 15% across a typical estate – over and above those savings that have already been achieved from the current controls.

Crucially, it is possible to prevent boiler dry cycling with a relatively low investment and a typical payback within two years, without conflicting with existing boiler control/ BMS strategies or compromising comfort conditions within the building. This is because M2G boiler load optimisation control works in a very different way to any other previously tried methods. By monitoring each boiler every second, the M2G is able to establish a profile of the current load being placed on each boiler; it can identify immediately if the boiler is dry cycling to compensate for standing heat losses or if there is a genuine heating demand and dynamically respond accordingly.

This continual adaptation to BMS/optimiser variable set points strategies ensures the M2G is able harmonise with and complement existing controls without artificially altering the boilers’ original designed set points or the system temperature and therefore enables additional cost savings to be delivered without compromise .

Another important point, in terms of life cycle costs, is that M2G units are self-learning and require no maintenance or seasonal calibration and can be easily transferred to new boilers if existing plant is replaced. In addition, removing the boiler “dry cycles” and “short cycles” will put less stress on the boiler and other components. The underlying reasons for boiler dry cycling and an explanation of how M2G prevents it are included in an animation that can be viewed at sabien-tech.co.uk