Water scarcity: Mitigating the risk
PAUL ANGUS, hydraulic engineering team leader at WSP Sydney, discusses the merits of creating a water strategy to mitigate the risks of water scarcity and to take advantage of the vast water conservation opportunities available.
Under AS/NZS 4360:2004 – risk management, the likelihood and consequences of the water supply impacts of climate change can be classed as extreme. The changes will occur over the same timeframe that engineering assets are designed for (i.e. a design life of 80 to 150 years). As climate change intensifies, water supply constraints, either through scarcity or supply interruptions from extreme events, will lead to increasing pressure on businesses to implement water efficiency measures.
How does this risk translate to a building or a facility? Water is often not seen as a high business risk, based on its relatively low cost, but risk lies in the security of its supply, which is paramount to the continuity of a business. In a building, if water supply is cut for any given reason, for a period of time the building becomes uninhabitable and unproductive, and, as such, a loss of earnings will be incurred, whatever the nature of the business.
For example, data storage is one of the major on-site services that a building requires to operate. Because water is used as part of the building’s data room cooling system, any water supply issues will impact a tenant’s productivity and profitability. From a risk perspective, it makes good business sense to mitigate, where possible, against the risks associated with scarcity of water and interruptions to water supply.
In order to build confidence with tenants and investors alike, it is paramount to ensure a water strategy is in place. It can be applied to any commercial, retail, industrial and/or public sector facility where, in the event of water failure, any water-reliant systems, for example fire protection systems, are fully considered.
KNOW YOUR WATER FOOTPRINT
First, a building’s water footprint needs to be understood. How much water is being used productively, or wasted unnecessarily, where is it being used and for what purpose? Water audits and water metering programs play a pivotal role in understanding a water footprint. They will draw attention to areas of unusually high consumption or ageing infrastructure that will soon become a problem.
Various studies undertaken globally indicate that by connecting water meters (and sub-meters in tenanted areas) to a building management system (BMS) water usage can be reduced through the provision of data changing water use behaviours. Once a building’s water footprint is understood, an informed plan of action can be developed to mitigate risk. Such plans should include the detection of leaks and upgrades to aging water infrastructure.
On average, approximately 10 percent of a buildings water usage is from undetected leaks. The majority of new buildings have systems incorporated to detect water leakage as they occur, saving vast amounts of time, labour, expense and water related damages. When retrofitting a building these systems should be considered.
WATER SAVING SOLUTIONS
Issues associated with ageing infrastructure, such as hydraulic plant, pipework and sanitary fixtures often escalate and can require immediate action. When undertaking these upgrades, reactive or quick fix practices should be avoided as they will inevitably cause more financial burden than relief.
Taking a proactive approach to upgrades is beneficial. For example, replacing out-of-date, inefficient plumbing fixtures with low-flow outlets, or alternatively providing fixtures with aerators to reduce water consumption are effective methods of addressing water efficiency issues that can provide significant savings within a complex building with multiple fixtures and fittings.
However, the full extent of other consequences should be considered. For example, when retrofitting low flow fixtures, consideration to existing drainage pipework diameters, gradients, as well as the overall distance should be carefully considered, as this may unintentionally result in future blockages occurring. Retrofitting waterless urinals may seem an effective solution; however, existing waste pipework must be fully assessed as the pH content of urine can quickly corrode existing copper waste pipework, making a quick solution an expensive high priority issue to replace the pipework. These situations are rarely budgeted for, straining an already limited budget, and causing frustrations for building operations staff and tenants.
STRENGTHEN YOUR WATER STRATEGY
Any water strategy needs to look at mitigating risks and maximising opportunities. Such opportunities may include the payback and life cycle analysis of system upgrades and assessment of water reuse and recycling opportunities.
A good example is regeneration of the Central Park Precinct in Sydney, which aims to achieve a six-star water rating. The water usage for the cooling towers, which was recognised as a primary consuming element, will be minimised and replaced with recycled water provided by a recycled water treatment plant.
Other sustainable measures include a recycled water network that has a membrane bioreactor (MBR) plant in the basement of one of the residential buildings. In addition, rainwater from roofs, stormwater, groundwater, sewage and irrigation water will all be reused, reducing potable demand by up to 50 percent.
It should be noted that opportunities can also present unaccounted for costs or risks. For example, when considering the opportunity to implement and retrofit systems such as rainwater harvesting or greywater recycling systems, the full life cycle cost needs to be considered, and water is just one cost. The energy required to pump the water from the basement to all WC fixtures within a high-rise office building can have a significant impact on electrical loads and costs. Energy efficient pumps may help; however, the full impact should be assessed with consideration to the location of the water systems in retrofit applications.
A robust water strategy should focus on operational measures as well as engineering solutions. It needs to avoid reactive measures, identifying both short- and long-term solutions that can be staged. It must also be integrated with other strategies; for example, energy management, as a building is a complex web of interconnected systems that cannot operate in isolation of one another.
The strategy can be aligned with benchmarking tools such as LEED (Leadership in Energy and Environmental Design), Green Star and NABERS (National Australian Built Environment Rating System). These tools can help a building’s performance to be publically recognised and, as such, increase its overall asset value. A forward-thinking water strategy should not only mitigate the risk of business continuity, but also take advantage of opportunities – be they environmental, cost or reputation related.
Paul Angus transferred to the WSP Asia-Pacific Sydney Office from WSP UK in early 2012 to lead the hydraulic engineering team. Angus has strong commercial and technical capability in developing and delivering hydraulic design strategies and solutions. He specialises in providing a sustainable approach to system design, including water conservation, recycling and generating innovative engineering solutions. In addition to Central Park Precinct, WSP recently undertook the relocation of Bloomberg offices into an existing building at 1 Bligh Street in Sydney, achieving a LEED Platinum rating with a key emphasis on reducing water consumption.