Water efficient fire protection systems
Only 18 months ago, few in the fire protection industry were talking sustainability, let alone taking any action.
That’s the experience of A.G. Coombs strategic development director Bryon Price. However, he has now noted a big change.
“Recently, there’s a huge focus on reducing the amount of water wasted in fire sprinkler systems, and the types of materials used to construct them,” Price says.
“Our job is to satisfy ‘green’ requirements without compromising safety.”
Based in Melbourne, Australia, the A.G. Coombs group has more than 60 years’ experience providing building services – from design, construction and commissioning through to service, maintenance, technical advice and support.
The group focuses on fire protection; heating, ventilation and air-conditioning; refrigeration; mechanical; and multi-services installations in commercial and industrial buildings.
Price says the challenge for sustainable water-based fire protection systems is to quantify the amount of water being used.
In the past this has been unhindered – and un-metered.
“When fire sprinklers were first introduced into high-rise buildings in this country it was rare to have any metering of the system’s water use, but water wasn’t anywhere near as precious as it is now.
“Until recently, regulations and industry practices haven’t kept up with the times.”
Price says negative reports in daily newspapers depicting city buildings flushing water to drains during drought conditions attracts the attention and ire of the general public, who are unaware of what testing is being done in the building and why.
“They don’t see sprinkler systems being tested for safety, they only see water being wasted down the drains. That sparks public outcry. But even so, we have to do more to stop wasting water.”
Price believes that metering of water-based fire protection systems is inevitable.
“No one has put any definite timeframes on the implementation of meters, but water authorities are talking about metering in the next two to five years.
“One problem I believe they are encountering is metering the existing building stock. Many buildings have older systems that don’t lend themselves to easy upgrades to include meters – and you can’t meter some buildings and not others.”
Geoff Flower is Price’s colleague, employed as engineering services manager for Walker Fire Protection, a specialty fire protection company in the A.G.Coombs Group. The company has previously issued a white paper, Green Fire Protection – 10 Key Principles, which outlines suggestions for saving water and improving environmental performance.
“Saving water is still the number one priority for ‘green’ fire protection,” Flower says.
“So we look at ways of maximizing water savings beyond metering.
“We encourage design that configures fire pumps to incorporate a recirculating test water tank – or at least discharge test water to a graywater reuse system.
“In many cases a modest-sized tank of 5,000-10,000L (1,320-2,640 US gallons) can be incorporated into an existing system to capture and recycle test water.
While the size of the tank is not that big, over the course of a year they can save many times that amount in water that would have been flushed down stormwater drains.
“Reusing water for fire system testing is best, however in cases where the captured test water cannot be recirculated the system can be designed to provide water for flushing toilets or for roof gardens and similar purposes. It’s better than running all that water to waste.
“Some installations use their tanks to capture and recycle water for testing the sprinkler systems.”
However, recirculating tanks can sometimes have technical and space issues in existing buildings. Where do you put a tank that size?
“Ideally these things should be planned for early in the overall design stage of the fire sprinkler system,” Price says.
“They can be quite difficult to retrofit because of the space requirements and the extra plumbing involved.”
Flower points to another upcoming water-saving initiative – installing flexible droppers on sprinkler heads. This technology was introduced as a labour-saving technology but is rapidly becoming important for saving water.
“Relocating just one sprinkler head because a wall has been moved beneath it, or a new device or appliance has been installed that has no protection, can result in a loss of up to 30,000L (7,925 US gallons) in cases when the system has to be drained down to allow for the reinstallation.
“This can largely be avoided in systems that use flexible droppers. Where the sprinkler head has to be moved only a metre or so, flexible droppers are ideal. In the lifecycle of a building that can happen many times.
“Unfortunately, the downside is that the flexible dropper has a greater pressure drop than its fixed-pipe counterpart. So when we add all that up, it usually means the need to have bigger pipes upstream. The hydraulic performance of the system is different – which can make flexible droppers problematic to retrofit in an existing building.”
Installing additional system isolation valves to each floor is another obvious water-saver, Flower says.
“Draining down only that portion of the building can save much water and time for a simple sprinkler relocation.”
He knows of installations that incorporate this, although some building owners baulk at installing extra valves.
“On a standard system, with one valve servicing three, four or even five floors of a multi-story building, the amount of water that has to be drained is huge.
“But to install valves on each floor is costly, not just for the hardware but for the monitoring of each valve. Sometimes a total overhaul of the monitoring system is required because the existing control panel doesn’t have the capacity. And when you’re talking about a 30-story building you might be adding 30 extra valves that need to be monitored.
“Additionally, at each one of those valves you need to have a drain-down point, and ideally it won’t be a one-inch (25mm) pipe; it would be a four-inch (100mm) drain pipe. These also can be difficult and costly to retrofit.
“The other issue is the cost of water – at less than US$3.65 per thousand liters the return on investment in water savings for building owners is usually not there.
“Even with expected increases in the cost of water it is unlikely there will ever be a viable commercial payback for installing these systems.”
In other words, building owners need to put a high value on resources and want to be seen as good corporate citizens. Or, to achieve Green Star status (Green Building Council of Australia star rating system), they may have to install these systems. There isn’t a direct commercial incentive.
“About 2% of the building stock in Australia is under construction, so it’s easier to design new systems incorporating water-saving initiatives,” Flower says.
“But that means it will be a struggle for the other 98% to adapt. The challenge for us is to incorporate the new requirements into the existing building stock.”
Price and Flower point to recent revisions in fire protection system inspection, testing and maintenance Standards in Australia as one of the key ways to reduce water use.
“Unlike other building services, fire services don’t use water in normal operation,” Flower says.
“Apart from system failure or modifications, it is only during a fire or system testing that water is used.”
In Australia, National Fire Protection Maintenance Standards consolidation and revisions now permit the weekly testing regimes to be done monthly. This results in an immediate and substantial reduction in water use, even if the water is not captured.
As Flower points out, the change is highly unusual in the context of Standards and regulation. In the normal course of events requirements increase as Standards, codes and regulations are revised.
“Although the maintenance frequency can be reduced, additional system requirements are imposed to ensure that system integrity and reliability are not jeopardized.
“Fire suppression system designers, installers and building owners need to be aware of the latest updates to regulations for obvious reasons, especially when major changes have occurred that can dramatically affect testing requirements, materials and the like.”
Price and Flower say another possible approach for new construction and refurbishment is to base fire safety design on performance. In a building that would require fire sprinklers under a prescriptive approach, it may be possible to do without them by using other fire protection measures. This could include more compartmentalization to minimize the spread of fire.
“However, from an energy efficiency perspective, modern designers and architects are trying to open up buildings with more natural airflow, natural lighting, shared spaces and the like. This runs counter to designing a building without active fire suppression, such as a sprinkler system.
“Sprinklers are very good at controlling and suppressing fires – they have an excellent record,” Flower says.
“Thus the use of sprinklers can open up many other possibilities for energy-efficient sustainable building development, so the trick is to find a good balance. It requires close coordination of the entire design team to work through the particular features of each building and decide on the best approach.”
Another aspect of sustainable fire systems relates to the type and amount of materials used.
Green initiatives include the use of zero halogen cables in the monitoring networks in lieu of cables using PVC. Flexible sprinkler droppers save on materials over the lifecycle of a building, whereas fixed pipes needing minor adjustments would be cut and the old pipes and fittings sent to landfill.
“In the past, very little recycling has been conducted on fire sprinkler systems,” Flower says.
“But that is starting to change. It is important to ensure that system performance isn’t degraded by reusing existing pipe, so caution is necessary.”
Price says smart builders involve fire suppression system designers in the design process.
“Instead of installing a basic pipe system early in the building’s development, then returning to make many changes to the sprinkler layout once fit-out has begun, there is an increase in an integrated approach that incorporates the base building and tenancy fit-out. This avoids unnecessary changes.
“Factors dictating these moves are the shortening of building/fit-out timeframes, and often a commitment by tenants before the buildings are completed. It allows for the one-stop approach.”
Price says it is crucial for fire protection engineers, like many other engineers in the building and construction industry, to deal with four principles of sustainability:
“If you design a system to be flexible it is less likely to be changed and result in environmental effects when meeting a new requirement. If you prepare for change that can’t be foreseen at the time, something adaptable will require less modification.
“Designing a system that’s durable with a good lifecycle will mean reduced environmental effects into the future. And if it is designed with an understanding of maintenance and testing requirements, you can reduce the environmental effects of these necessary activities.”