Ontario residents were asked to reduce their use of electricity in the province this week as a combination of the hottest summer in years and limitations on supply threatened the reliability of the system. It's the fourth time this year that an appeal to conserve energy has been issued.

Last week the situation became so serious that the Independent Electricity System Operator (IESO) reduced voltage by five per cent, forcing a "brownout." While most people didn't notice the reduction in power, reports said a hospital in Kingston complained that some of its equipment was affected. The Canadian Press says that police warned drivers in some areas to be wary of traffic lights that could malfunction because of the cutbacks.

The IESO says public appeals to conserve electricity are issued during periods of high demand, and when reserves are low. Last week, several generating units were undergoing maintenance and were not available when needed. The equipment used to bring more power from the United States is also straining in the hot weather, making it difficult for the province to import more electricity.

Last Wednesday, Premier Dalton McGuinty told reporters that it will be two or three years before enough new facilities are built to handle the increasing demand for power. That means voltage reductions may become more common until new facilities are built.

The IESO says that although there are several new power generating projects being built and others in "various stages of discussion, development, or negotiation," new generating and transmission facilities, particularly in the Toronto area, are urgently required over the next decade in order to meet the expected demands for electricity.

A 10-year outlook by the organization says the Ontario government's decision to phase out the coal-fired generation plants "represents the largest and most significant electricity system change ever undertaken in Ontario and involves major technical considerations. It also involves significant risks and challenges that need to be addressed." The IESO says new generating plants must be tested for a period of time to ensure their reliability before the plug is pulled from the coal-fired plants.

Meanwhile, in addition to asking consumers to conserve, there are now financial incentives in place to encourage people to turn off unnecessary lights and appliances. For years, consumers were protected by price subsidies that resulted in Ontario Hydro racking up a debt of more than $25 billion. As of last April, cost-based pricing means that consumers and businesses now pay five cents per kWh for the first 750 kWh of electricity used, and then 5.8 cents for each additional kWh. In November, the pricing will change and the lower price will apply to the first 1,000 kWh of electricity used, but next May it will change again to reflect summer hours when there is more light - at that point, the lower price will only apply to the first 600 kWh.

The province is also bringing in "smart meters," which will determine how much energy consumers use at different times of the day and year. There will be rewards built in for those who conserve energy during the peak demand hours of the day, which are 8 am to 8 pm. By 2010, all homes in the province are to have the smart meters.

IESO is appealing to consumers to cut back on all energy use, particularly during the peak demand periods that occur late in the afternoon and early evening as people return home from work. It's asking homeowners to set air conditioners to 26 C or higher; keep blinds or curtains closed to keep rooms cooler; hang clothes to dry rather than using clothes dryers; and use fans to cool rooms rather than air conditioning.

Some other energy saving tips from IESO:

• Turn off lights, TVs and other appliances when they are not needed.

• Wash laundry in cold water.

• Use energy-efficient compact fluorescent lights instead of standard light bulbs.

• Take short showers instead of baths.

• Install a low-flow shower head.

• When possible, use small appliances such as a microwave, slow cooker, electric kettle or toaster oven instead of the stove.

• Take clothes out of the dryer and fold them when they are still warm to prevent wrinkling, and cut down on ironing.

• Shower and run your dishwasher, washer and dryer early in the morning or late at night.

This week retail businesses were also asked to watch their energy use. The Conservation Council of Ontario launched the Doors Closed Ontario campaign to encourage stores and restaurants to close their doors when using air conditioning. The council says that if only 10 per cent of Ontario's 100,000 stores and restaurants run their air conditioning with the doors open, 200 megawatts of energy is wasted -- a significant amount when Ontario is facing the threat of brownouts and even rolling blackouts.