Update: I got a watt meter because I was concerned that the sous vide heater (rated at 1000 watts) might be too expensive to run. I found that at the low temperature of 37.8C, it only uses about 17 watts most of the time. I used about 1.5 kw/h over the 36 hours, and this worked out at 30 cents for a whole batch of yoghurt at Nova Scotia electricity prices.
Update: I got a watt meter because I was concerned that the sous vide heater (rated at 1000 watts) might be too expensive to run. I found that at the low temperature of 37.8C, it only uses about 17 watts most of the time. I used about 1.5 kw/h over the 36 hours, and this worked out at 30 cents for a whole batch of yoghurt at Nova Scotia electricity prices.