I would not shut off the water heater at the gas valve because you would have to relight the pilot later and leaving it on at a reduced temperature will help prevent rust in the combustion chamber and it probably won't use more gas than the minimum charge anyway. 

I'm not familiar with what type of system you have.Generally speaking, the most cost effective way to stay warm in the winter is to dress in layers and set a reasonable room temperature in the high 60s or maybe 70, but some tenants like to sit around in their shorts and t-shirts with the t-stat set on 80, then complain when the heat bill is high. 

Despite the local temperatures in Chicago still regularly hitting 90 plus, the cold winds of winter are barreling toward us like a freight train.

Differing temperatures outside the home and inside, moisture producing factors in the home, and not enough air flow and air exchange, can lead to moisture build up and often can be seen on the inside of windows.5.

We have tings such as infrared cameras, temperature and humidity meters, mold air and surface sampling equipment, and many years of experience.  4) While mold is not regulated, asbestos and lead are very highly regulated, with potential huge fines, even time in federal prison. 

At the momvent I on the snow boots clearance Cote D and the temperature here today was 33 degrees Celcius.

Did it crack due to recent freezing temperatures?

If upper tenant does not have to worry about heating cost, then hopefully they will not keep the temperature too low for savings and freezing the lower tenant.

"In the wealthy, northern suburbs of [Athens], where summer temperatures often hit the high 90s, just 324 residents checked the box on their tax returns admitting that they owned pools.

The best thing you can do is run the air conditioning, keep it set at a moderate temperature, say mid-to-high 70*'s.