Opportunities for upgrading legacy BMSs
New technology is opening up new opportunities to retrofit outdated building-management systems with controls that can revolutionise energy practices within older buildings. Anders Norén explains.
With new-build developments off the agenda, it seems that the route towards a low-carbon Britain hinges on cutting carbon emissions by transforming existing building stock. Government advisory body, The Carbon Trust, estimates that 60% of the buildings that will be standing in 2050 have already been built. What’s more, nearly half of these buildings were constructed before 1985, which is when the energy-efficiency requirements of Part L were introduced.
Low-carbon refurbishment, rather than ‘green’ works that start from scratch, has already found its place as a popular response to the downturn. Greater Government legislation, tightening emissions targets and the growing ubiquity of corporate social responsibility mean that carbon reduction cannot wait until brighter economic times.
Added insulation, energy-saving equipment, behavioural change campaigns and microgeneration of renewable energy have all gained recognition as carbon-cutting measures that can also reduce fuel bills.
However, what of the most aged, inefficient buildings, stunted by building-management systems (BMSs) installed many years ago that cannot adapt to modern energy practices?
Energy within buildings is not exclusively lost through the fabric or through inefficient lighting and equipment. A substantial amount of energy can also be wasted as a result of outdated building control systems. Without the ability to closely monitor energy use across an entire site, in order to identify and target any energy leaks and anomalies, an organisation is left open to massive energy wastage. Investigations by leading consultancies, TNO, Senternovem and ISSO, have revealed that energy consumption in buildings is, on average, 25% higher than should be, and this is largely because of incorrect climate-system settings. In a staggering 70% of buildings, the climate systems do not work at an optimum level.
The solution, for many organisations, has emerged in the form of new flexibility via state-of-the-art building-control systems. New technology makes it possible to upgrade legacy BMS, reusing existing cabling and sensors/field devices. Previously, older buildings, burdened with outdated controls technology that it was uneconomical to fully replace, had no choice but to ‘make do’. However, the ability to retrofit old systems with new controls represents a major move forward — a chance to implement better energy efficiency without the added expense and disruption of completely replacing the BMS.
There is added cause for historical buildings to require existing cabling to be left in place. Listed buildings are notorious for their stringent conservation regulations, which can limit the scope for installing new equipment. Replacing legacy cabling and sensors can, quite simply, cause irreparable damage to delicate walls, ceilings and floors within pre-20th century buildings. However, even for non-historical buildings, disturbing the walls and ceilings is cause for consternation. Replacing existing infrastructure adds both expense and disruption. The noise and dust caused by complete replacement of BMS components can add health and safety complications and result in staff being displaced from their usual work areas.
For Marlborough College, an independent boarding school in Wiltshire that dates back to 1843, the issue of achieving better energy efficiency was complicated by the historical nature of its buildings, the sprawling nature of its campus (comprising more than 40 buildings) and a crude BMS that controlled its onsite energy management. Marlborough chose to keep in place much of its existing BMS infrastructure, but replace its old stand-alone series of building controllers with a Priva Internet-based, remote-access BMS that allows for site-wide energy monitoring and targeting.
‘The college liked the fact that with Priva there are no protocol or modem compatibility issues,’ says Derrick Lailey, project engineer for PA Collacott & Co, the Priva partner responsible for installing the new system. ‘We explained that the system would create a central head-end computer, located in the IT service racks, whereby important performance data could be accessed over the web at three PC points, one in the central boiler house and the other two in the estates office. Additionally, the head mechanical engineer/boiler house manager would have a laptop that would allow him to connect remotely to the system and take control of the BMS from anywhere in the world.’
Importantly, because this system does not require screened cabling, it can utilise existing BMS cabling (assuming it is still fit for purpose) thereby safeguarding the building’s fabric. In all cases, a professional assessment of the existing cabling and sensors/field devices was made, and these were used wherever product integrity allowed their ongoing use. By working closely with the college staff, in particular the IT department and mechanical engineers on site, it was possible for the team to ensure a smooth transition between the two systems. Ultimately the process was completed in the most cost-effective manner, with disruption to the school’s everyday operation kept to the absolute minimum.
As Marlborough College found, an up-to-date BMS can mean the difference between a site that uses excess energy, racking up higher fuel bills and a bigger carbon footprint, and a streamlined, energy-conscious site. While updating a BMS in the past meant replacing outdated infrastructure, technology has become flexible enough to work with what is already in place. Legacy cabling and sensors are no longer a barrier to achieving a smaller carbon footprint; in fact, they provide a route forward.
Anders Norén is managing director of Priva Building Intelligence.