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April 19, 2009 | Gerald Flood | Winnipeg Free Press
Hydro's new home a living, breathing creature
"The new Hydro building on Portage Avenue is a living thing, a glass palace that breathes earth, wind and fire.
If that sounds too poetic, it isn't. The fact is that the most sophisticated green office tower in Canada really does breathe earth, wind and fire, elements as old and natural as the Earth itself, all as freely and readily available for our use as they were before we instead embraced electricity and fossil fuels.
Let's start with earth. The earth below the $278-million building is complex, but as complex as it is, the temperature after a depth of about four metres is 5 Celsius -- everywhere, always. The building's geothermal system is designed to capture that heat and bring it to the surface because, as weak as that energy is in temperature, it is massively and constantly available -- free.
To bring it to the surface, 280 13-centimetre tubes were drilled down 17 metres through dirt, clay, sand and gravel under the building's 90,000-square-foot base. The holes were then drilled down 98 more metres into the limestone layer under Winnipeg.
Glycol, a better medium for heat transfer than water, is circulated through the tubes, carrying heat from the building in summer to be released into the relatively chilly rock, and up to the surface in the relatively chilly winter. But always it is five degrees of heat that is brought to the surface, which means it must be enhanced in both summer and winter lest the building always be an uncomfortable 5 C.
In winter, geothermal heat is mixed with fresh air as cold as -35 in heat exchangers. That mixed air becomes as warm as 10 C in the exchangers and is then released into three 70-foot tall, glass-walled atriums stacked one upon another up the south side of the building, facing the sun.
The solar heat is measured as it shines through the windows of the three identical south-facing atriums. On a sunny day, solar heat is mixed with heat from the earth to raise the temperature to about 20 C. On cloudy days or in winter, the use of gas-fired boilers increases. The boilers heat glycol in tubes embedded in the concrete pillars and floors of the building. The concrete warms in winter, cools in summer, and either radiates heat or retains coolness. It is a principle as old as adobe.
The geothermal system, working in co-ordination with solar energy streaming through windows, is sufficient to provide an astonishing 100 per cent of air conditioning in summer and 60 per cent of heating in winter.
The building is so energy-efficient, in fact, that it uses less than a third of the energy required to meet Model National Energy Code standards. The code standard is 295 kilowatt hours of energy per square metre of flood-space. The Hydro building will use just 91 kilowatt hours. A typical commercial building in Winnipeg uses 570 -- six times as much energy as the Hydro building and almost none of it from geothermal or solar sources.
The savings on energy are more than sufficient to overcome the surprisingly modest additional costs of building green.
"It adds about five per cent more to the cost of building, but when you reduce your energy needs by 60 per cent, it creates tremendous savings over time," Hydro spokesman Glenn Schneider said. "We want to demonstrate that to the business community."
But back to the atriums. No doubt they will soon be things of beauty, with plants and furnishings and the sound of water falling down 280 21-metre-long mylar cables to humidify the air inside while providing spectacular water features. But today they are still under construction -- huge, barren rooms that expose the ingenious engineering that makes them work, that makes them, in the words of project manager Tom Gouldsborough, "the lungs of the building."
Recall that the atriums are the places where fresh air is mixed with heat from the earth.
All of that heating causes the air to at once expand and to rise. The pressure of expansion and the rising air creates a draft that flows from the bottom of the atrium and into crawl spaces beneath each of the six floors of office space that look out over each of the three atriums.
That draft flows under every floor and up through vents into the rooms above. The movement of air is so gentle as to be no more than a zephyr's kiss, hardly noticeable anywhere on any of the 18 floors and 690,00 square feet of the building served by the three atriums.
But the air does move, from the south side of the building to its north side, washing everyone and everything in its path with perfectly fresh, perfectly heated and moisturized air. The ceilings on each of the 18 floors are 11 feet high. As the air rises from the floor vents and moves northward, it also rises in the 11-foot-high space, carrying to the ceiling and away all airborne contaminants and odours -- like CO2 and bad breath -- being created in the vast working spaces.
When the air gets to the north side of the building, it again enters smaller atriums -- six three-storey atriums, as opposed to three six-storey atriums on the south. The smaller atriums feed the air into the "solar chimney."
The solar what? One of the striking features of the Hydro building -- other than itself -- is the rectangular tower that juts from toe to head of the north face of the building. Though it looks like a 114-foot-tall blade to cleave north winds, it is, in fact, a chimney up which all the fresh air drawn into the building from the south exhausts to the north.
At the very top of the clad tower is an open, 25-metre-tall, glass-walled room. Inside are black iron pipes filled with sand. The sun shining through the glass is absorbed by the black pipes and retained by the sand as the temperature inside the chamber rises to as much as 100 C in summer.
Heat created and stored in the pipes helps to draw air through the building, much like what happens when you light a fireplace and encourage a draft by stuffing burning paper up the chimney to dispel the heavy cold air above and draw smoke-filled air from below.
During the nine warmest months of the year, all heat and stale air are exhausted out the chimney. But during the coldest months, the chimney is closed and the warm, stale air is drawn back down the chimney to the basement parking lot, where exchangers extract heat and exhaust the stale air at ground level. Heat gathered in the basement is then sent to the atriums for recirculation.
In other words, unlike most conventional office buildings that recirculate stale air and exhaust heat from their chimneys, the Hydro building recirculates heat and exhausts stale air.
Another striking feature of the building is that it looks different from every angle, and at different times of the day.
The different exterior prospects are a result of its footprint -- imagine a huge capital A lying on the ground, as opposed to the square or rectangular footprints of most buildings.
The point of the A is the solar chimney, which faces due north. The little bar joining the bottom of the capital A are the atriums, which face due south to capture as much sunshine as possible year round. The long arms of the A are what are called the "lofts," the working areas arrayed on the east- and west-facing sides of the atriums. The whole thing stands on a three-storey "podium" at ground level above the basement and one-level carpark.
The shape means that the building shows a different facade in every direction -- and at different times of the day.
How's that? Well, consider that what really sets the building apart are its glass walls, not just clear glass, but perfectly clear glass. It is made perfectly clear by removing the iron that tints conventional glass green. It was imported from Europe and can be found nowhere else in Winnipeg.
The glass is so clear, in fact, that it is all but invisible. Visitors new to the building (me, for example) have been known to give themselves a bit of a start by bumping into glass walls.
The clarity of the glass, however, is not about what you might or might not see in it, but rather to allow maximum penetration of light and radiant heat.
When you are talking about glass walls that rise some 90 metres, that's a lot of light and heat, often too much. And so the exterior of the building is actually two walls of glass, an inner and outer wall separated by one metre of open space. In that space and behind every sheet of exterior glass are high-tech venetian blinds. But nothing like the ones found in homes. The slats of each of these blinds can be opened or closed independently by mechanisms controlled by computers that measure the intensity of the sun, its changing daily alignment and seasonal inclination.
The computers also compare the solar information with weather information collected at electronic weather stations at the top and bottom of the building and adjust the slats to allow more or less light and solar heat into the building.
That is why the building might look transparent in the morning but appear "blinded" white in the afternoon.
The white slats are constantly fluttering open and closed. One second you can see outside unobstructed, the next it is like looking through a soft pastel veil. Flutter, flutter, flutter.
Sometimes the slats are closed to block 90 per cent of the light; sometimes they tilt up to reflect it onto the ceilings to brighten the lofts.
The space between the glass walls allows for maintenance and window washing. But it also allows for opening windows to let fresh air directly into the lofts, a rarity in modern office towers. When windows are opened, the computers notice and adjust all the other factors.
Recall that the ceilings are 11 feet high. That means the windows are, too. The height allows for a maximum penetration of light into workspaces. So much light is allowed into the building in this way that its lighting system is on less than 25 per cent of the time, and at that it is usually at low radiance.
Artificial light is supplied by T-5 fluorescent tubes, each skinnier than a cigarette but many times brighter than standard fluorescent tubes. Sensors monitor light levels and increase or diminish artificial light as needed. The transition between the level of natural light and artificial light is so gentle as to go unnoticed.
At night, motion sensors control lighting. If there is no one moving in the office tower, it goes dark, and its breathing slows while it sleeps."
Winnipeg Free Press, Sunday April 19th 2009