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Liquid pool covers

Energy savings

The result of implementing the liquid pool cover at Volunteer Pool significantly decreased the facility’s consumption of natural gas over the four-year average. Four years prior to this pilot project, the facility used an average of 136,200 m3 (4,809,858 cf) of natural gas per year. In 2009, after a full year of using the liquid pool cover, natural gas consumption was reduced to 92,800 m3 (3,277,201 cf), representing a 32 per cent decrease.

In terms of seasonal consumption, the facility was able to reduce its use of natural gas by 26.3 per cent during the winter, 49.5 per cent in the spring, 37 per cent in the summer and 42 per cent in the fall.

In October 2009, through the use of the liquid pool cover, and the resultant reduction of humidity in the natatorium, the facility was also able to add outside damper controls (i.e. a valve or plate, which stops or regulates the flow of air) to the air handling unit to decrease the amount of outside air required to maintain humidity and temperature levels inside the facility.

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Facility staff manually add the liquid pool cover to spa on a daily basis.

The following December, operations staff also started using insulated tarps on the pool after hours and the natatorium lighting was retrofitted from 800-watt high-pressure sodium to 400-watt induction lighting. These operational changes, in addition to using the liquid solar blanket, further reduced the facility’s natural gas consumption by almost half based on a comparison between the four-year average and 2010 (January to May).

For example, between January and May the facility used a four-year average of 89,100 m3 (3,146,537 cf) of natural gas. In 2009, during this same period, natural gas consumption totaled 67,500 m3 (2,383,740 cf). However, in 2010, consumption was reduced further to 42,200 m3 (1,490,279 cf), representing a 51 per cent decrease over the four-year average and a 37 per cent decrease over 2009.


During the pilot project, the City of Thunder Bay’s facilities and services division determined that the energy savings combined with the reduction in humidity levels and space temperature created an approximate 40 per cent savings in natural gas consumption. Although the goal of the energy management strategic plan is to reduce consumption, the city also realized an approximate $15,000 savings in natural gas costs. Based on these results, and the success of the Volunteer Pool pilot project, the city continues to use the liquid pool cover product at the facility, as well as at its other indoor aquatic facilities, including the Canada Games Complex.



Franco 2Franco Marchese is a supervisor with the facilities services department in the City of Thunder Bay’s facilities and fleet division. He is responsible for the city’s aquatic facilities, community centres and parks buildings. Marchese has worked with the city for more than 15 years in various capacities, including electrician, construction and maintenance and has developed a broad range of skills such as building heating ventilating and air conditioning (HVAC) and controls. He can be reached via e-mail at

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