By Robert Mikula
As purveyors of fountains and other forms of decorative or recreational water, watershapers are faced these days by an immediate challenge: What we do is generally classified as “unsustainable” by an environmentally conscious public because they erroneously assume poor performance when it comes to the way we approach water consumption, use of space and energy efficiency.
On the surface, these are serious knocks on our output, but the increasing fact of the matter is that these allegations can be overcome in many instances by combining smart design choices with the sort of holistic, integrated design process described last month in the first of the three articles in this “Sustainable Trends” series (click here).
Let’s pull apart these three charges, which we at Crystal Fountains (Toronto, Ontario, Canada) often encounter in discussion of fountain projects. We do so in full confidence that the principles defined here apply to other watershapes as well, from commercial swimming pools to ponds and waterparks.
In this article, we’ll deal with water issues; next time, we’ll conclude the series with detailed coverage of issues related to space allocation and energy consumption.
The perception of fountains as dastardly wasters of potable water is clearly among the biggest roadblocks we encounter when trying to incorporate a waterfeature into a project.
It is a common, for example, to hear in early project meetings that all fountains require massive inputs of fresh water that gets sent straight to waste once it is used. That is a widespread misconception – one easily set aside because most modern fountains are designed as closed-loop systems that filter, treat, recirculate and carefully control flows to ensure water conservation.
(These days, even systems that use open-loop freshwater supplies can be somewhat sustainable. If, for instance, a fountain uses low-flow jets where the water drains into a subterranean cistern that supplies water for irrigation – and if that system deploys proximity sensors so the fountain is only activated when users are present – such a project might be viewed as sustainable. Creative solutions are definitely part of the current design environment, but always and only with public health and safety uppermost in mind.)
In addition, we’re ready to report that if the source of a fountain’s fill water is a reservoir of highly treated recycled water – non-potable by all standards – then the fountain’s demand for increasingly precious fresh-water resources is significantly reduced, so much so that these systems are recognized and accepted among groups that monitor “green” building practices. Stored, treated rainwater is a perfect candidate for topping off water supplies in such systems.
|Overcoming the perception that fountains use and send potable water to waste is a key hurdle in the process of incorporating ornamental water within an environment for which sustainability has been set as a goal. It’s all about education – and patiently dispelling 'accepted wisdom' about how these waterfeatures really work.|
It’s more than a façade: Indeed, water conservation and re-use are paramount values in designing today’s waterfeatures, particularly in public and commercial settings. As such, design development always addresses the potential for use of alternative water sources, including grey water, rainwater and condensate from air-conditioning systems – to such an extent that a fountain’s potable water needs are mostly offset.
But note: These alternative, non-potable sources often require specific pre- or post-water treatment systems to bring water quality and chemistry to safe levels for waterfeature applications. It is always wise to check local codes applicable to the jurisdiction in which the fountain is being built!
In addition, it cannot be overstressed that an integrative process approach that encompasses the fountain within the overall site planning as early as possible is highly recommended when pursuing alternative source-water systems: Everything works out best, we’ve found, when a watershape is designed in conjunction with overall facility- or building-maintenance systems.
These alternative source-water systems can be used with fountains in two ways: Either the excess water provided by the system can be used to supplement some of the fountain’s water needs, or the fountain may be used within the water-supply stream itself, polishing the water before it is transported to other areas for non-potable applications.
With polishing – that is, simply cleaning the water up to a usable level via the fountain’s own filtration and treatment systems – we create multiple opportunities for recycling and recirculating the water to maximize its use, always in accordance with local codes. We’re also looking forward to a day when we can work with solar power to drive all of these treatment and delivery systems and ease the ongoing cost of fountain operation.
TRASH TO TREASURE
Let’s start with rainwater as the first of the alternative water sources, because it is almost universally available. Indeed, any commercial project with a flat roof in an open area is an optimal candidate for one of these simple systems.
In some circumstances, water collected and stored in reservoir tanks can be used to supplement more than 50 percent of a site’s water needs – in flushing toilets, performing laundry services, irrigating landscape features and, most important in this context, feeding water to a fountain. Along the way, harvesting rainwater also reduces run-off, which is a significant aspect of stormwater-management systems in most jurisdictions.
Any water collected by a rainwater system requires pretreatment before it is used for a fountain or in most other applications. It must be properly filtered and chemically treated – that is, polished – before it is diverted for use in a fountain or elsewhere. This same principle holds true for any type of water being reused for other purposes, even if those applications are non-potable.
The intention is to eliminate impurities or pollutants that might find their way into the water during the collection process. Once polished, the treated rainwater is ready to be sent to the fountain to top off the system and replace any losses attributable to splash or evaporation.
|Water for use in fountains can originate from a range of sources, including rainwater collection, prudent use of greywater or recycling of the condensate generated by air conditioning systems. In all cases, success involves integrating the waterfeature into the space’s overall water system and thinking about these interrelationships in the earliest stages of project development.|
Greywater – that is, the waste water from showers, sinks and baths – can also be repurposed and used elsewhere so long as the application doesn’t involve human contact or consumption. This is a tremendous resource: Because it is much more predictably available than rainwater, greywater can reduce a building’s water consumption by up to 50 percent more than a rainwater-capture system.
But if greywater is to be used in interactive waterfeatures, it must comply with stringent water quality/chemistry requirements to avoid the spreading of certain waterborne diseases. Again, knowledge of local codes is key: If treated greywater is not seen by local authorities as an appropriate source for interactive waterfeatures, then it cannot be used.
It’s important to note, of course, that what’s not available for fountains can be used on site in a variety of ways that free up other non-potable water sources for use in fountains. As a result, project teams often find themselves considering a range of systems designed to put greywater to use, even if there’s no link of any kind to a fountain.
Greywater sources include laundry-to-landscape systems, which are useful in irrigation; branched drain systems, which take water from laundry services as well as showers and sinks and use gravity to direct the water to storage tanks; pumped systems, which deal with circumstances in which areas to be irrigated are uphill from the drainage system; and sand-filter-to-drip-irrigation systems, which remove clogging sediments from the water for use in landscape maintenance.
In commercial settings but also in substantial residential projects, pumped systems and sand-filter-to-drip-irrigation systems are usually employed in greywater management. The other two systems – laundry-to-landscape and branched-drain – are simpler and are mostly reserved for residential projects.
A USEFUL BYPRODUCT
The third alternative source of fill water for fountains is generally the least appreciated – that is, typical air-conditioning systems in commercial buildings. These units consist of an air-handling system that circulates air to occupied spaces to maintain comfort. As the air returns from the cooled space, it is mixed with outside air – a necessity in maintaining a healthy environment.
When the air mixture passes through the air-handling unit, it moves through a cooling coil that lowers the air’s temperature and thereby reduces its ability to carry water vapor, which cools and condenses into water droplets. In years past, this condensate was often considered a nuisance, but now this water, especially when produced in volume by large heating, ventilating and air-conditioning (HVAC) systems and refrigeration equipment, is being reused and has become a significant source of water.
The extent of this resource is dependent on climate and seasonal factors, but where it’s a possibility in commercial contexts, the collected water can be used for irrigation, industrial processes, cooling tower supply – and for nearby waterfeatures.
Depending on the HVAC design, local climate conditions and predominant building use, the amount of condensate available for collection in a commercial building can range from three to 10 gallons per day per 1,000 square feet of air-conditioned space. Thus, a smallish 10,000-square-foot office building can produce more than 15,000 gallons of condensate water per year, with large-scale complexes producing significantly more than that.
|Minimizing evaporative losses is an important issue in design development. Systems that effectively atomize water, for example, are best deployed in less-arid places, but placement in shaded areas can help even where humidity is low. It’s tough to calculate or anticipate these losses (or savings), but applying some common sense in the selection of display effects certainly will help.|
Much like harvested rainwater, this condensate must be properly filtered and chemically treated if it is being used for non-potable/fountain-type applications, especially if those uses invite possible human interaction or create airborne mist. Ultraviolet light, chlorine tablets, ozone injection and/or raising the water temperature to above 140 degrees Fahrenheit are all suitable methods for eliminating potential biohazards.
Unlike other non-potable sources, however, the low mineral content in condensate causes less fouling from mineral residue in the evaporation process, thereby making this water ideally suited for use in waterfeatures. The key here is anticipating use and appropriately sizing a reservoir during the project planning stage – relatively small if the tank is to serve the continuous make-up needs of a fountain, much larger if the system is intended to feed an irrigation system as well.
Throughout all such considerations, water loss in a fountain system is a significant factor. Even in an enclosed-system fountain, there will be losses attributable to evaporation, splash-out and wind.
There’s no exact way to determine the amount of these losses, as they depend on wobbly variables ranging from air and water temperature to humidity, wind velocity, the type of the water effects and the level of human interaction. There are, however, several rules of thumb for estimating evaporation rates – and design techniques that serve to minimize the amount of evaporative loss.
For example, it’s a given that high air temperatures, low humidity, strong winds and sunshine will increase evaporation, while low air temperatures, high humidity, rainfall and cloud cover will decrease it. Evaporation also depends on the water’s surface area, which means a covered system or playdeck is recommended, with an ability to reduce evaporative losses by up to 90 percent.
Water loss can often be greatly reduced by making appropriate design choices and by designing appropriately for the available space. In arid climates, for instance, you can greatly reduce evaporative loss by ensuring a fountain's design is suited to its environment – that is, by using low-flow effects such as pop nozzles, water droplets or laminar jets; by reducing the footprint of the fountain basin; by shading the fountain basin or completely blocking exposure to direct sunlight; and, in sunny locations, by avoiding the use of dark colors with fountain finishes.
In windy areas, evaporative losses can also be reduced by including anemometer-driven sensors in the system that will monitor wind velocity and manipulate the height of jet effects and reduce the fountain’s profile in case of a good blow – or even shut the system down, as needed.
Let’s close out this part of the discussion with a case study – this one having to do with “World Voices,” an art-and-water sculpture situated in Dubai within the lobby of Burj Khalifa, the world’s tallest building.
|Jaume Plensa’s ‘World Voices’ is a delicate display of watershaping art – but even in the desert of Dubai it has been made in a responsible, sustainable way by fully integrating it into the water systems used in the world’s tallest building.|
Designed by internationally renowned artist Jaume Plensa (who is also acclaimed for Chicago’s Crown Fountain), “World Voices” creates a memorable (yet sustainably responsible) effect by using half-inch slugs of water released from the ceiling to create organic rhythms on a collection of golden cymbals below.
The value of this case study rests in the emphasis we placed in the design development phase on optimizing the fountain’s performance well before construction ever began through use of design simulation. In this instance, we pre-tested creative concepts while simultaneously assessing the splash and wind conditions.
Our chief concern was air movement courtesy of the building’s air-conditioning system. To assess this factor, we ran computer simulations and built a full-scale mock-up at York University to verify that, at terminal velocity, the half-inch slugs of water would maintain its coherence (that is, didn’t break up) while cutting through the building’s air envelope.
This series of articles is an expanded version of a course prepared for use by architects participating in AEC Daily’s continuing-education programs.
AEC Daily is registered provider of these courses and offers them free through it’s web site, which also offers extensive product information and industry news. For more, visit aecdaily.com.
Again, fitting fountain and other decorative or recreational water systems into overall design packages requires early involvement in the design process so that system needs are considered and accommodated from the outset. By using an integrated, integrative approach in which all possible water sources beyond municipal supplies are sized up and balanced, it’s possible to rationalize the inclusion of waterfeatures and make them fully defensible components of substantial projects, even in arid climates where such use seems counterintuitive to the average (and sometimes skeptical) observer.
As we’ll see next time, the case for waterfeatures becomes even more compelling when site issues and energy use are folded into the calculations. And this isn’t just applicable to fountains: On this level, a favorable case can be made for just about any watershape in just about any environment.
Robert Mikula is director of special projects at Crystal Fountains, an international waterfeature specialist based in Toronto, Ontario, Canada. Mikula has more than 20 years’ experience in design and project management and is also a registered landscape architect who spent several years designing aquatic theme parks before taking his current post. He is also active on the education front, having participated in many seminar programs and written numerous magazine articles on water effects, illumination and systems design. For more information, visit www.crystalfountains.com.