By the end of the summer, most Waterloo Region residents will be living with smart meters, but whether that means you pay more or less on your electricity bill, depends on your habits, and whether you're willing to change them.

Time-of-use billing means hydro rates will vary depending on when you're using it, so when you opt to run your dishwasher, washing machine, dryer and other appliances will have an impact.

As for the reason behind smart meters, Ontario Energy Minister Brad Duguid says "It's about shifting our time that we're using energy as much as we can, as much as it's convenient for us to do that, to be able to save having to build more generation in the future."

Milton, Ont. was one of the first areas in the province to adopt the technology, and residents have now been living with smart meters for more than three years.

Prof. Ian Rowlands and a group of his graduate students at the University of Waterloo studied the impact on a number of families in the area.

According to Rowlands, "Fifty-five per cent of homes had an increase in charges under time-of-use rates and 45 per cent would have had a lower charge under time-of-use rates."

One family learned firsthand that if you don't change your habits you'll end up paying more. That's what happened to Milton homeowner Andrew Keen and his family.

Keen says "There were some bills that were really ridiculously high, probably almost twice as much as they were five years ago and that's when I really started tightening everything down."

It was a wake up call for their household, and their first big change was to do laundry during off-peak hours, after 7 p.m. or on the weekend.

"I look at it now," Keen says, "and realize how much we have to work around the schedule to make sure that we're not using too much energy during that time."

But with a young family, and regular meal times being important, some energy consuming activities like cooking still fall in the higher priced periods.

Keen says that works against the family, but it can't really be avoided.

It confirms what Rowlands' study found, that people who don't change or "Those who are active in their homes during the day, yes, will be subject to the mid- and on-peak prices."

That can be a challenge for seniors, families with young children and other consumers dependent on electricity during the day.

Ontario Progressive Conservative Leader Tim Hudak says it doesn't add up, "It's driving up costs for families and it doesn't work for small businesses and farmers as well."

But hydro companies and the Ontario government say time-of-use billing more accurately reflects the cost of generating the power.

When demand is the highest, it's more expensive, but when demand falls, electricity costs less to generate. The hope is time-of-use billing will encourage conservation.

Rowlands says "One of the incentives, one of the motivations for a time of use regime is to encourage changes in people's behaviour."

However, Keen says nothing seems to be enough, "I shut off the lights, I have energy efficient bulbs, and the air conditioner we keep it set just to take the humidity out of the air pretty much, bills still keep getting higher no matter what."

So while for a majority of homes time-of-use billing shouldn't lead to major increases in electricity costs, for some, unless you pay attention to energy use, smart meters could mean more money out of your pocket.