Hitting the hot spot
Take a moment to visualise just how your everyday life would be impacted without a modern plumbing system; when it comes to advancements in plumbing technology, we are very lucky compared to numerous locations around the world, where access to clean, running water is not so readily available. Have you ever stopped to realise where we would all be without running water or flushing toilets?
Unfortunately, being provided with a copious supply of clean hot and cold water on demand is indeed a luxury, which many end users expect as matter of course – until there is an issue due to a plant system failure, resulting in the facilities being out of action and numerous complaints. There’s nothing like starting the day with a cold shower to dampen your spirits.
As our cities continue to transform, the boom of economic growth is also resulting in increased premium for net lettable area. Existing properties need to adapt and implement a refurbishment strategy to the facilities in order to entice clients to remain in an ageing building, and not be tempted to vacate and move into the latest tower development, with all the mod-con facilities.
End user expectations are exceptionally high, particularly when paying a premium. Offsetting the increased level of expectation for modern and luxurious facilities to save costs can be tough. Modern buildings are
also implementing a ‘green’ agenda due to the rising cost of water, becoming far better at informing end users about the importance of water conservation. Any reduction in the usage of hot water will inevitably have a significant impact on reducing consumption of both water and energy in building facilities.
Commercial buildings, especially high-rise towers, are significant consumers of water and energy. The energy cost required to heat water is one of the prime energy expenditures in the industry, right after cooling and heating. Rising utility costs also play a pivotal role in both hot and cold water usage.
On average, hot water systems have a life expectancy of between 10 and 15 years. They rely on a preventative maintenance regime to remain as efficient and effective as possible, in addition to reducing energy usage.
As designers, there are various ‘green’ initiatives, as well as targets to reduce the impact on the environment, that force us to become experts in ticking the right boxes from a sustainability perspective. But are we, as engineers, focusing on gaining sustainable credits, instead of the end user’s requirements and expectations?
Sustainable water strategies continue to be at the forefront in building design. This can be aligned with a range of industry benchmarking tools, such as NABERS (National Australian Built Environment Rating System), LEED (Leadership in Energy and Environmental Design) and Green Star. These tools elevate the building’s performance to be publicly recognised and as such, increase its overall asset value.
When designing or replacing a hot water system, size does matter – or does it? The hydraulic consultant walks a very fine line between achieving the necessary credits for an environmentally sound and sustainable building, versus the end user expectations. Complaints, due to an ageing or poor performing plumbing system, are inevitable and the repercussions are a costly exercise for any business. As with the design and installation stage, key consideration to the operation and maintenance, including end of life replacement of the hot water system, is critical.
A significant risk exists in the security of both hot and cold water supply and distribution, which is paramount to the continuity of a business. In a building, should the hot and cold water supply not be available for a significant period of time, the building becomes uninhabitable due to public health issues. This, in turn, becomes unproductive and a loss of earnings will be incurred, whatever the nature of the business.
Ensuring the hot water plant is well- maintained with a preventive strategy is paramount. However, breakdowns will occur when you least expect them – more often than not during peak usage periods. It’s a scenario that facility management teams have recurring nightmares about!
Picture the scene: it’s 7.30am and suddenly the phone starts ringing off the hook with complaints due to poor hot water performance. Only a few weeks earlier, the new state-of-the-art building won an accolade for sustainability and water conservation measures, but has a hot water system that is underperforming for the third day on the run. Multiple instances of a recurring fault are now leaving the facility management team feeling hot under the collar.
It pays to fully understand the operation of the hot water system in the building for which you are responsible. As a way of conserving energy, the hot water storage temperatures should never be tampered with or adjusted lower than initially commissioned.
This approach and lack of understanding of hot water systems can have dire consequences, including overall performance, but, most importantly, a significant risk of legionella occurring. Being educated in how the system operates is paramount. A great example of this is when it was discovered that a leisure facilities management team, who were looking to reduce energy consumption, decided to try switching off the hot water plant overnight and back on again during the peak period in the morning. Not only did this affect the hot water recovery period in the evening, but also hot water performance in end of trip facilities in the morning, as the required storage temperatures were not available.
This unnecessary action had the opposite effect to reducing energy and associated costs and, of course, resulted in increased costs to the client, due to heating substantial volumes of cold water to the necessary hot water temperature. We won’t labour the point about the legions of complaints!
Water (and energy) wastage occurs in end of trip facilities, where the shower is operated for a prolonged period of time or turned on and carelessly left to run. The period of time from opening a hot water tap or shower effectively depends on the overall distance from the water heater to the tap, the pipework diameter and flow rates. To overcome the prolonged wait for hot water to be available at the shower or basin, eliminating dead legs of pipework, by installing a secondary circulation pump, is best practice, as well as insulating all the hot water pipework, in accordance with the Building Code of Australia requirements. Hot water return circulators ensure the hot water flowing through the flow and return system is always available almost instantly.
All the best laid plans from a design perspective review and incorporate the best practice approach. However, it pays to be diligent during the installation stage. For example, on a recent visit to swimming pool facilities, I discovered the non-insulated hot water pipework temperature at approximately 60 degrees Celsius had entered the inlet of the Thermostatic Mixing Valve (TMV). Due to the pipework being recessed into a block wall and uninsulated, this resulted in heat transfer from the pipework to the tiled wall, heating a substantial surface area. This was dangerous to touch and shocked me when I accidentally brushed up against the tiled wall.
Not only would this item be an OH&S (occupational health and safety) issue, in particular for the elderly or children, but it would have an adverse effect in increasing energy costs. The hot water pipework dropped from the ceiling above and recessed with plaster into a blockwork wall before entering the TMV. The warm water pipework exiting the TMV at approximately 43 degrees Celsius was then reticulated to four showers. These problems and energy wastage could have been easily avoided at the installation stage.
Concerns associated with ageing hot water plant, pipework and pumps commonly escalate and, more often than not, require immediate action. Taking a proactive approach to upgrades is beneficial.
Sustainable hot water systems, such as ground and air source heat pumps and solar hot water systems, can be easily implemented on new buildings at the design stage; however, retrofitting can be somewhat troublesome, due to lack of plant room space or the orientation of the building’s roof.
It is therefore important for any hot and cold water replacement strategy that any risks be identified and mitigated, as well as any opportunities fully exploited. These may include a review of the payback and life cycle analysis of system upgrades, while – in parallel – an assessment of water reuse, recycling opportunities and legionella risk assessments should be undertaken.
Any robust strategy should focus on operational measures, as well as engineering sustainable solutions. It needs to avoid reactive measures, identifying both short- and long-term solutions that can be effectively staged.
A forward-thinking water strategy is an important aspect of a building to not only mitigate the risk of business continuity problems, but also to take advantage of opportunities, be they environmental, cost or reputation-related.
Written by Paul Angus, who is an associate director – Hydraulic Services at AECOM, based in Sydney. He 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. For further information visit www.aecom.com.
This article also appears in the February/March issue of Facility Management magazine.