Hello everyone,

I live in a (rented) guesthouse made from a converted garage. The total area is about 400-500 square feet. I am having problems controlling the excessive humidity.

As far as I can tell, the humidity comes from these sources:
Once a day showers
Cooking
Washing/drying dishes
Outdoor humidity, which is usually around 50-80%, with temperatures usually in the 60's-80's

The tools I have at my disposal to control temperature and humidity are:
Windows/doors I can open
A ceiling fan
A gas radiant heater
A dehumidifier, which I am limited in how much I can run, because my landlady complained that it increased her electric bill too much, though I do not have enough information to quantify how much this actually was, but I now have a watt meter for it.

The humidity becomes a problem in the following ways:
Heavy condensation on the skylight (to the point that it drips down on me) and windows
Condensation and mold growth on the parts of the concrete slab that are exposed
Condensation on some patches of walls that have poor circulation

I have two questions for you all:
First, my landlady claims that no previous tenant has had problems with humidity. Do you this plausible?
Second, how would you suggest controlling the humidity and condensation, given the tools at my disposal (or anything else you can think of), and given the fact that I cannot run the dehumidifier more than an hour a day for electricity use reasons?