Point of thermostat?

I like the addition of the thermostat. My Sims live in Oasis Springs....so I just assumed they'd never need to turn it on during winter as it doesn't get that cold in the desert. But there were a couple of days when my Sims were complaining about being cold. I turned it on for a few days when they complained...and the bills were $69K. Outrageous. Almost bankrupt my Sims. I was so worried about the following Monday of bills, that my Sims went hardcore making money. Once I turned the thermostat off.....bills dropped back down to $15K which is normal for that household.

So lesson learned....only turn it on when absolutely necessary, otherwise prepare for your Sims to be broke lol. I will be starting Summer in 1 Sim day in Oasis Springs....and I already see a few heat waves on the calendar....& it got hot during Spring, & my Sims would lounge in toddler pool to cool off. I'm a bit worried about Summer in Oasis & if I'll need to use that thermostat. I finally got my Sims a decent amount of money, as I'm trying to open a retail shop....but if those bills skyrocket back to $69K.....they'd be toast. Even though the bill amount is crazy high....it's easy to make money in the game.....so I kind of like the challenge or the possibility of money being tight in my game.