My mom lives in a pretty small house, and it’s pretty cozy. It’s just two bedrooms, a living room, kitchen, and one full bathroom. This means me and her end up showering back to back when we get back from the local beach. We like to take the pets for a swim and walk the beach in the morning while the tourists are still asleep, then go home to shower and have our breakfast. As it happens, the back to back showers means the vent in the bathroom is on for a long time to deal with the humidity; At the same time, my Mom is usually in the kitchen with the vent hood on frying breakfast meat. She turns the vent on for me, cause I’m vegetarian and the frying fumes can make me nauseous. This works out okay, however a few weeks after my visit my mom always notices a significant spike in the utility bill, however she couldn’t figure it out for the longest time–I don’t mess with her thermostat, and we don’t take hot showers, so the water usage shouldn’t be it. Even with the spare bedroom occupied, I’m only in it to sleep at night, so were not running more lights. At last, I was able to figure it out for her–the vents! If you leave an exhaust vent running, its really sucking out the cool air your air conditioning system has been working to produce. In less than an hour, an exhaust vent can remove a whole home worth of cooled air. I suggested her to get a little dehumidifier for the bathroom, and it really did prevent the extra cost on the power bill! Vents are such a small thing, however they can undo all of the work your HVAC system puts in if you’re careless!