Giant Canadian construction project incorporates low carbon heating and cooling: Don Pittis

The company that made an international splash by air conditioning downtown Toronto without air conditioners has more energy-saving innovations in the works.

With the help of a gigantic purpose-built thermalreservoir, EnwaveEnergywill add an entire new neighbourhood to its underground low-carbon heating and cooling network with the project calledThe Well on the site that used to be headquarters for the Globe and Mail.

Not only will the seven-building retail, residential and office complex in the city's business centrebe added toEnwave's lake-water cooling system, but the company is in the process ofincorporating a series of revolutionary energy and carbon-saving techniques to keep residents and workers at The Well comfortable.

Digging deep

Even for construction-mad Toronto, the site is large, with more thana million square feet ofoffice space, nearly 2,000 residences and more than 400,000 square feet of retail. The project's backers estimate that it will serve about 11,000 people daily.

"It'll be 100 per cent heated and cooled by Enwave," saidCarson Gemmill, the company's engineering lead for Toronto.

The project's name has a double meaning, asits northern access is onto Wellington Street. But at the core of the project is the well itself, a multimillion-litre underground hole that extends into the bedrock from below the lowest parking level to a few metres above sea level.

The solution stored in the wellit is not just waterwill act as a giant thermal battery, said Gemming, cold in the summer for air conditioning and hot in the winter for heating.

Enwave, which began life as a publicly owned utility used to heat municipal buildings and hospitals in the city using a centralized or "district" network, garnered global media attention more than a decade ago for its innovation in low-energy cooling.

Using thedrinkingwater supply thatthe city draws from the chilly depthsof Lake Ontario, Enwavesucks out some of that coldness from the just-above-zero Celsiuslake water, and circulates it in downtown buildings to cool them without the costly electricity usually required for air conditioning.

Power cuts

Although climate change was not at the topof political agendasin those days, Enwave decreased the city's peak electricity load by cutting the need for power from the coal-generating stations that at that time still supplied much of Ontario's power.

One efficiency of the well at The Well is also a matter of peak demand. The tank is filled overnight with colder waterwhen there are low periods of demand for air conditioning. Enwave, now owned by the conglomerate Brookfield, adds to the thermal battery without increasing its cooling or heating capacity.

While traditional heating for large industrial buildings likehospitals usessteamboiled by natural gas-burning furnaces, the heating loop for The Well will be based on hot water of the type familiar to people who have radiators in their homes.

This water to be pumped for heatingdoesn't need to be boiled and that opens the door togreen heating alternatives, including electric heat pumps, an energy efficient method of concentrating heat from lower heat sources.

"One of the things that's kind of interesting about our system is, people may not realize, in the winter months, even on days like today, we still actuallyhave a significant cooling load becauseof the large data centre clients we serve," said Gemmill.

Large urban centres around the world like Torontohave massive centralized server farms to act as nodes in data shared on the web to make it quicker to draw up frequently needed information. Individual companies such as banks have localdata centres, as do cloud computing providers.

All are huge producers of heat that must be drawn away with cooling systems to prevent system breakdown. But whereas elsewhere that heat is vented to outdoor air, Enwaveis engineeringa system to capture and reuse it.

Pumped heat

"Really, like 13 Cwill be the temperature of our chill water coming back, but you run that through a heat pump,"said Gemmill. "So you can produce 60 Con the other side of the heat pump, which is useful for space heating."

As Gemmill explains, heat pumps arelike using a refrigerator in reverse, where heat is drawn out of air or water that may notfeel especially warm.

After a recent CBC story on switching to lower carbon powerelectric heat, a number of readers pointed out that heating with electricity using baseboard resistanceheaters can be prohibitively expensive outside Quebec. But as Gemmill explained, using a heat pump cuts that cost dramatically.

"Roughly, for every one unit of electricity you use [with a baseboard heater], you get one unit of useful heat," said Gemmill. "Heat pumps are three to one. So they are three times more efficient."

Currently the two giant steam generators Enwave operates to create steam for heat run on natural gas but the switch to hot water allows the new system to use leftover heat from the steam furnace, said Julia St. Michael,Enwave'sdirector of sustainability engagement.

"That hot water network right now is using waste heat from our facility, but in the future we'll be able to add lower carbon sources of heat," said St. Michael. As carbon taxes make gas more expensive, pumping heat from sewer water, industrial sources, as well as server farms, becomes more cost effective.

One of the biggest commercial efficiencies of Enwave'sdistrict heating operation is that it means individual building managers don't have to have their own air conditioners and heaters or the staff to run them. Centralized warming and cooling also means theyhave more space to lease out, said St. Michael.

But as Enwave showed with its deep water cooling system, the other advantage is that as new low-carbon technologiescome into the mainstream, they can be introducedonce at source and instantly apply to every building in the network.

Follow Don Pittis on Twitter @don_pittis