What are my rights to use a space heater? [WI]

Tldr; renting the upstairs of a large house and it’s too cold. What are my options?

Sorry on mobile for bad formatting.

I rent the upstairs of a large house. I only pay rent, the lady who owns and lives in the house (downstairs) covers electric, gas, etc. I do not have a lease.

The upstairs had a hard time maintaining temperature. During the hot summer it was often 78-80+ with the air on and me using multiple fans. When she turned the air off I would use the box fans in the windows to help cool down. I was kind of glad when fall came as a relief from the heat.

But now that it’s winter it’s been very cold up here. Uncomfortable to sit at my computer with my hands not in pockets. She has the heat on but since it’s a large house the ground floor is good but up here it was frequently 63-65. This was in late October/early November. My parents insisted on getting me a space heater even though I didn’t think the owner would be happy about it (she didn’t want me to use a portable air conditioner during the summer, the heat worsens my breathing problems).

So now I’ve been using a space heater when I get back from work every night. I only use it if I’m in the room, about 5-10pm each night, and I always turn off and unplug when not in use. It helps get the temp up to 67-70 after a few hours. When I get home after work the next day the room temp is back to 64 ish.

My parents are pestering me to tell my landlady about the space heater. She doesn’t know about it. My mom says it’s no different than the three box fans I bought for the summer (which ran for much longer). I don’t think she’d like the fact I’m using the space heater though, based on how she didn’t want me to use my portable air conditioner during the summer.

My rent payment is really good price, I would be willing to help pay part of the electric bill (though she hasn’t complained about it being high).

But my question is, if I tell her about it, or if she finds out about it by coming into my room, can she force me to not use it? Or evict me? I know by law she supposed to keep the temp at 67 during daytime hours right? But it hasn’t been that since early October.

What legal advice can you give me? Any help or direction is appreciated. Thank you