This article first appeared in the June issue of Building Services and Environmental Engineer (BSEE) Magazine.
Mick Pratt, commercial director, Water, Built Environment Services, ESG, explores how duty holders of commercial and other public buildings can ensure water systems in their care not only meet safety requirements but also boost resource efficiency.
In recent years, as sustainability has become a significant focus, and water and energy costs have continued to rise, the facilities managers of public buildings - such as schools and universities, hospitals and hotels - have been under growing pressure to re-assess how such resources are used. For many, using these utilities more efficiently is vital both to reduce costs and minimise the impact of the built environment on the natural world.
Whilst cutting the energy consumption of buildings has been a key efficiency goal for facilities managers for many years, increasingly we are now seeing public and commercial buildings turning to water reclamation as another way of cutting the use of limited resources. Data centres, for example, are starting to recycle the water used in their rapid liquid cooling technology to regulate the temperature of their computer servers. Office buildings, meanwhile, are beginning to utilise reclaimed water for flushing toilets and other non-potable applications.
Implementing these measures can go a long way towards shrinking a development’s overall environmental footprint. However, they cannot be undertaken without due consideration being paid to the effective disinfection of the water system. Each year in the UK, there are between 300 and 400 reported cases of Legionnaires’ disease - a severe form of pneumonia caused by the inhalation of Legionella bacteria. Unless the correct action is taken, these microbes can thrive in the extensive water systems of large commercial buildings.
As such, it is imperative that facilities managers find ways to balance these two concerns: effectively streamlining operating costs while also ensuring a safe environment for building occupants.
The traditional approach
Often, facilities managers of public buildings will use traditional biocidal products to disinfect the water systems in their care. Halogen-based chemicals, such as chlorine, bromine or chlorine dioxide, are commonly used in these situations.
Although these substances are effective when it comes to eliminating biological contamination, they can have a negative impact on water quality if they find their way out of the system loop. High levels of chlorine in domestic systems for instance, can lead to the build-up of carcinogens, such as trihalomethanes, in the water. If ingested, these chemicals have been linked with long-term health problems in both people and wildlife.
With these drawbacks in mind, more and more facilities managers are opting for alternative methods of water treatment that have less of an impact on the natural environment.
An allotrope of oxygen containing three atoms, instead of the usual two, ozone is an extremely powerful biocide which, when dissolved in water, is capable of eliminating bacteria, viruses, algae and microbial cysts. As a result, water can be recirculated in a loop system and be used over and over again, helping to reduce a building’s reliance on external water supplies, and increase resource efficiency.
Moreover, in contrast to chlorination, ozone does not combine with organic materials during the sanitation process to create carcinogens or other harmful by-products. It also rapidly breaks down into the more stable, usual form of oxygen again once contaminants have been removed, thereby eliminating the risk of harmful chemicals being released into the environment.
Reducing energy use
Facilities managers often look to minimise the energy used by hot water systems, usually as part of a wider initiative to reduce consumption across their premises. On commercial premises, hot water is typically stored at temperatures of 60°C or above and delivered to the outlets at a minimum of 50°C to safeguard against bacterial growth and ensure building occupants’ health and wellbeing. Whilst this is an effective means of disinfecting water, it can result in hot water systems accounting for up to half of a business’s energy costs, having a considerable negative effect on profits as a result.
However, one alternative technology, called electrolytic disinfection (ED), has the potential to eliminate the need for such high temperatures, or the addition of biocidal chemicals.
ED technology treats water using a small direct electrical current - a process known as electrolysis. This current generates biocides from the ions naturally present in the water, which then kill any pathogens present and provide a residual disinfection effect that prevents the growth of bacteria and other microbes. As demonstrated by a recent scientific study of a hot water system at a healthcare facility fitted with ESG’s ED technology, Protex!, bacterial levels can be reduced by as much as 99 per cent.
Thanks to such disinfection capabilities, ED systems can potentially allow facilities managers to reduce the temperature of stored hot water from the 60°C recommended by the approved code of practice for Legionella management (ACoP L8 and Technical Guidance HSG274). They can also circulate the water around the system at a temperature as low as 45°C. This can help significantly reduce a building’s energy consumption and streamline operating costs. What is more, ED technologies do not require the addition of disinfectants, reducing the risk of chemicals entering the wider water supply chain and safeguarding the wellbeing of the public and the environment.
The perfect balance
Whatever the nature or purpose of the building they are responsible for, there are significant financial incentives for facilities managers to find ways to minimise the consumption of fresh water and energy across their properties. However, when it comes to water usage, resource efficiency must always be considered alongside hygiene requirements to ensure the highest standards of health and safety for building occupants.
The water treatment approaches now available can enable facilities managers not just to meet ever more ambitious efficiency goals and stringent safety legislation but, by eliminating the need for adding disinfectants, reduce the building’s impact on the environment as well.