’S DISTRICT COOLING SERVICE

Enwave has been in the outsourced air conditioning business since 1997. District cooling was a natural extension of the company’s core steam distribution business as the same customers that required heating, also required air conditioning. While Enwave’s foray into the air conditioning business had always been premised on using natural cooling from the depths of Lake , the early stages of the business made use of conventional technology.

With two 1,500-ton absorption chillers at its newly constructed Chilled Water Plant, Enwave began supplying the expanded Metro Convention Center (MTCC) with 2600 tons of cooling in 1997. In 1999, plant capacity was expanded to 7700 tons with the addition of a 4,700-ton steam-driven centrifugal chiller as the customer base expanded to include the Air Canada Centre, the Steam Whistle Brewery and the telecommunications centre at 151 West, which was signed in 2000.

With the commissioning of the company’s signature Deep Lake Water Cooling project (DLWC), the chillers were retained for emergency backup and peak shaving on the hottest days of the year. However, the primary source of cooling would now be the cold water of Lake Ontario.

To date, over $110 million has been expended to bring in colder, cleaner drinking water for the City of Toronto and environmentally friendly cooling for downtown buildings. An additional $80 million will be spent by the time the system is fully built-out.

The Deep Lake Water Cooling (DLWC) system is a sustainable energy project, which replaces conventional air conditioning. Extending as far north as Queen’s Park, the innovative new cooling system will draw cold water from the depths of Lake Ontario to provide over 75,000 tons of cooling to buildings in . When fully built-out, the project will be able to provide enough cooling for over 3 million square meters of office space or 100 large commercial towers.

DLWC produces significant environmental benefits. Over 61 MW of electricity or the equivalent power demand of 6,800 homes will be displaced – easing the load on the Province’s already over burdened electricity infrastructure. 79,000 tonnes of CO2 emissions, 145 tonnes of NO2 emissions and 318 tonnes of Sulphur Dioxide emissions will be removed from the air shed annually.

Put more succinctly, the project’s environmental benefits are akin to permanently removing 15,800 vehicles from the provincial roadways.

Deep Lake Water Cooling uses the icy-cold water of Lake Ontario as its renewable energy source. The naturally recurring turnover of the lake surface ensures an abundant supply of 4°C water. Over the years, this cycle has created a permanent layer, or reservoir, of very cold water known as the hypolymnion that lies deep in the lake. Three High-

Density Polyethylene (HDPE) pipes, over 5Km long, follow the natural slope of the lake bottom and draw water from a depth of 83 meters, which is transported to Toronto’s Island Filtration Plant. There, the cold water is processed and directed to Enwave’s Energy Transfer Station, which is collocated at the City’s John Street Pumping Station. At this stage, heat exchangers facilitate the energy transfer between the icy cold lake water and Enwave’s closed chilled water supply loop.

Once the energy transfer process is complete, lake water continues on its natural to the City’s potable water system. Enwave uses the “coldness” from the lake water, not the actual water, to provide chilled water air-conditioning for Toronto’s buildings.

The new HDPE pipes, which have been ceded to the City of Toronto, replace water infrastructure, which is over 100 years old. Hence the dual benefit of the project – colder, cleaner drinking water and natural air conditioning.

Security has been built into the project at every stage. The three-pipe approach ensures redundancy of supply and allows for servicing of the marine infrastructure without interruption to the system. Pipes in the street are buried six stories below ground and encased in steel and concrete. Finally, 24/7 monitoring ensures reliability of service unparalleled in the marketplace.

Since it was first introduced in 1997, Enwave’s district cooling network has expanded to include some important Toronto landmarks such as the Metro Toronto Convention Centre (M.T.C.C.), the TD Centre, Royal Bank Plaza, Air Canada Centre, 151 Front Street West, One University Avenue and several other buildings. The network continues to expand as demand for cooling is facing significant upward pressure from the effects of global warming and the increased heating loads of telecom and computer equipment in downtown commercial and office buildings. Over the past five years, cooling loads in downtown office towers in most large urban areas have increased dramatically and mechanical engineers and environmentalists alike agree that the next five-year period will likely see these loads increase even further.

Cooling is delivered from our distribution network directly to a central point of entry at the customer’s premises. Therefore, unlike other energy sources, there is no need to install large expensive equipment. Hence, valuable building space is free to be used to generate revenue rather than add cost.