Will be leaving the house for a month, should I keep the exhaust fans in the toilet and in the kitchen running? How much could be the cost of keeping it on for a whole month?

I will be travelling for a month in winter. I want to prevent molds from forming. Will keeping this on the whole time make any difference? How much electricity will it consume? Lastly, what other tips can you give when leaving an aparmtent for a long time in winter?