The design of the Millennium Water Olympic Village was heavily influenced by a single imperative laid out in the official development plan: no potable water was to be used for irrigation. As the integrated design process took hold, however, the team pushed well beyond this simple water-saving concept. “We get plenty of water between October and May, and then little between May and October,” says landscape architect Peter Kreuk (see page 27). “So we would fill our cisterns quickly in October, and the water would just sit there till we need it in June. Meanwhile, the rest of the year, water would just keep running off the site as it normally would have. We wanted to do more with the water, so that’s why we thought of toilet flushing.”
Rainwater that falls on Olympic Village roofs is collected into basement cisterns. These tanks provide water for toilet flushing and irrigation, so municipal water is drawn for these purposes only when the banked supplies run low. The continual collection and use of rainwater throughout the year will provide a 40% reduction in total water demand that the Village places on the municipal reservoir – a far superior conservation performance than if the rainwater were used solely for irrigation.
“In SEFC we said, ‘We’re going to use a fit-for-purpose’ approach,” says Patrick Lucey, an aquatic ecologist involved in the design. “What that means is that we have two sources of water. For every cubic metre of water we capture from the rooftops, we get to “bank” in the reservoir an equivalent amount of water. Then, we get to use that banked water for irrigation during the dry period if it’s necessary, because we haven’t put a strain on the reservoir during the rest of the year like everyone else has.”
Capturing and using water that naturally falls on the site is one step closer to a system that mimics nature, which recycles water within local systems many times before it runs back to the ocean. While the Olympic Village does not reuse grey water [water left over from cooking or washing] as some sustainable developments do, Lucey says its use of rainwater banking is groundbreaking for the region.
“This whole notion of water banking and water balance is a huge step forward, and a very important and strategic change in the way the City and the region can begin thinking about its water supply. If everybody in the City did what they’re doing at False Creek, intuitively, the reservoirs would always stay full.”
Capturing and using water that naturally falls on the site is closer to a system that mimics nature
Systems and Cisterns
Buildings in the Olympic Village include an internal infrastructure entirely dedicated to the capture, storage and usage of rainwater. Water is collected from roof and building podium areas, then channelled to cisterns in each building’s basement. The rainwater is continuously pumped through courtyard water features and to toilet tanks throughout the building (see page 10) as demand requires. During the summer, water is directed towards irrigation as well.
Each building is able to draw make-up water from the municipal reservoir when needed. During times of heavy rainfall when cisterns are full, the buildings will shed excess water to the first tier of the Village’s two-tier stormwater system (page 14). “Moving forward, this is the type of system that can really help residents use water wisely,” says Jason Christensen of Keystone Environmental, which has provided monitoring services for the water in the cisterns. “It’s something that needs to happen, so it’s good to see.”
All Millennium Water roofs collect rain. But Parcels 2 and 9 have additional structures specifically for this purpose. “They’re like visors, at the top of the building above the parapet,” says Stu Lyon of gBL Architects. “They help rain-shield the building, and they extend its capacity to collect rain.” The water will fill rain barrels for use in rooftop community gardens before overflowing to the underground cisterns.
“It’s a very visible piece of sustainability for anybody working on those rooftops,” says Lyon. “No one sees the cistern in the basement, but they can see the water coming off the roof and going into the barrels. Hopefully this has an impact on the way people see their world, and gives them a better appreciation for the value of water, and for saving it for later use.”
Decorative Water Features and Water Quality
Within every parcel of buildings at Olympic Village there is at least one water feature – a rooftop stream, a reflecting pond, even a waterfall. These features help “celebrate water” – but they accomplish much more. “The features are used to keep rainwater from the cisterns in constant motion so it won’t stagnate,” says Peter Kreuk. “Running it through the water features aerates it and exposes it to sunlight, which helps kill off bacteria. It’s a pretty important functional role in the whole system.” Circulation will help maintain the water at a “recreational” quality level – the same required for public swimming at beaches and lakes. “That allows for a certain level of bacteria in the water,” says Bill Donald of Keystone Environmental.
“The recreational standard means, ‘It’s okay to swim in this water, and even swallow some of it, it won’t kill you.’” (Nevertheless, it is anticipated that toilets throughout the development will be labeled with a sign reading, “Do not drink.”)
Meanwhile, during hot weather, building water features will help provide a cooling effect for residents. “Passive design is subtle. The water in the ponds doesn’t do all the work – the surroundings and the local climatic conditions will contribute,” says SK Lai of Cobalt Engineering. “But if you sit there and the wind picks it up, the combination of our usually low humidity plus the effect of the pond will mean you’ll feel a little cooler.”
Walk through SEFC – the “celebration of water” is everywhere you look. Water has been brought back into the landscape – it’s on the roofs, it’s in the piazzas, it’s in the basements. It’s extraordinary.
Patrick Lucey, Aqua-Tex
With extensive landscaping on the Millennium Water buildings, making sure plants are watered during dry periods is important.
“There is an automatic irrigation system throughout the project,” says Kreuk. “There’s a weather station and groundwater soil sensors, so if it has just rained, the irrigation system won’t go on, but if the soil is dry and there’s a scheduled watering, it will. It’s based on plant needs and soil conditions, as compared to a standard system where you turn it on in May and it goes on every week until you turn it off in September. It will reduce water use for irrigation by almost 50 percent.”
Rainwater Toilet Flushing
Toilet-flushing is one of the most water-intensive activities in the modern home – which is why using rainwater for this purpose can have a dramatic effect on reducing the demand for municipally supplied drinking water. (See chart, page 6.)
But will residents adopt rainwater toilets with pride, or prejudice? Although the water is expected to eventually run clear once the building landscape has settled and fine organic matter has generally processed away, it is possible that the water may be slightly coloured due to its natural condition. For this reason, the system is designed so that future strata councils can install an additional filtering system if desired.
Heat Recovery and Water Pre-Heating
“If you look at the top of a typical apartment building in the winter, you’ll see misty condensation coming off the roof,” says SK Lai of Cobalt Engineering. “That’s excess heat – it’s basically being dumped into the environment and doing nothing else. In the Olympic Village, instead of dumping that heat, we put it back into the system.”
Turn on a hot water tap in Olympic Village and you feel warmth captured from a number of sources in the building: cooling systems in the suites, which extract heat during hot weather; parkades, which are warmed by cars and building activities; commercial spaces that generate heat from refrigerators, lighting, cooking and high customer volume; and on a few buildings, solar panels. Heat pumps recycle and transfer this energy, which is then used to warm potable water in a large tank with a coil running around the inside, called a heat exchanger.
Lai says Vancouver’s potable water tends to be quite cold – around seven degrees Celsius. For use in a bath or shower, energy from the Neighbourhood Energy Utility is used to bring the temperature up to 45-50 degrees. “To increase the efficiency, we use waste energy to pre-warm that water as much as possible,” says Lai. “Then we don’t have to use the [NEU] to heat the full amount, which is the savings we’re looking for.”
Peek inside the walls in Parcels 3 and 6 and you’ll see the way of the future. Gone are the metal pipes used by plumbers for generations. “This is the only high-rise development that I’m aware of in North America that has done a plumbing system entirely in plastic,” says Jim Myers of Jeda Mechanical, the company that plumbed the parcels. Myers says in the past, plastic piping did not meet fire codes, but newer products (Wirsbo and Aquatherm) now do.
Myers says this makes the plumbing system more sustainable and efficient in several ways: plastic pipes last 75-100 years, where copper typically wears out in 15-20, requiring costly and wasteful re-piping of the entire building; water flows more smoothly through plastic, so pipe sizes can be reduced and walls built thinner, increasing interior space; plastic pipes are less labour intensive to install; and plastic pipes can be recycled at the end of their life. “This is the way all projects should go,” says Myers. “This system will last the life of the building.”
Physics and Common Sense
Initially, there was concern that if a breach ever occurred within the heat exchanger used for water pre-heating, the potable water could become contaminated (the heating medium contains chemicals to keep the piping system clean). City officials required a double-wall heat exchanger – a system with an air gap between the heating medium and the potable water.
The trouble, says SK Lai, is that “air is known to be a very good insulating medium. Heat exchanging through an insulator is kind of a waste of time. So we worked with the City to sort this out.”
The answer turned out to be gravity. Engineers realized the heating medium would never circulate above two storeys – the highest level of commercial space – whereas potable water will fill pipes to the top story of each building. Therefore, the potable water system is always under significantly more pressure than the heating medium. If a breach occurs, potable water will infiltrate the heating medium – not the other way around. Based on this (plus sensitive electronic monitors), the City approved the more efficient single-wall heat exchanger.
“If you walk around the site, what you’re looking at is common sense and simplicity,” says Lai. “Sometimes being green is just coming back to the simple laws of physics.”