With the utilities on, the building temperature stays relatively the same.

The average lead temperature is "warm" for direct mail and it takes about 40 leads to convert one into a deal, so it is not worth your time to do direct mail unless you can commit to at least 4,000 mailers per month.

Have water, fire, moisture, temperature, motion sensors, voice interaction with customers, throughout the systems.  

How do you account for a cold front in February with temperatures below zero for 2 weeks? 

@Bin Chen I am not an HVAC professional, but in my experience every thermostat in my properties will heat the property to the set temperature.

The weather gets fairly cold in the winter and when the temperature drops to 5 degrees and a furnace goes on the blink expect to pay 200% more than the average cost for a repair, or pay for water damage caused by frozen water pipes.

Needless to say I did not buy one as our temperature regularly gets down to -20.

Requirements, 10 x 20 bunker, "solid" door, water and humidity dry, temperature moderate or controlled.   

IG: @MattPriestJr I have properties that I rent by the room in King/Pierce/Snohomish Counties.Many pro tips.For heating, I use Nest Thermostat and "lock" the temperature on 68 degrees. 

If you can't do that, they make boxes you can put over the themostats in your tenants apartment, you can set it to room temperature and lock the box.