The concrete slab will move and shift over time - concrete actually expands and contracts with temperature while porcelain and ceramic tile do not. 

I have (for our system) water and antifreeze temperature logger data collected every hour for the past several years.

The only thing I could think applies is that it says no Warehouses (?)

The temperature in the Portland area in my opinion is that many people are trying to adjust but validate.

Being in the tech space, maybe you want to find a way to blend the two, like others have with different products they've developed and brought to the market.Maybe you'd like to invest passively in real estate, there are a ton of platforms/services/sponsors for that.Then of course there are the more traditional active investing paths like self storage, multifamily, mobile home parks, office, warehouse, parking lots, raw land, the list goes on and on.I recommend researching the different strategies here on BP to figure out which is best for you.

The hot water temperature was 140 degrees F at the time of testing.

Building and then renting a 20,000' warehouse to marijuana growers. $110/s.f. to build and a 10% return.

How do I find them? 

Fall & Spring HVAC Service Target Date: April and October This service can aid in early detection of costly problems and save the cost of expensive, emergency service.A/C Service Includes: Check condenser coil, adjust operating pressures, monitor safety controls and starter capabilities, clean or replace filter, adjust blower components, calibrate thermostat, measure for proper temperature differences, clean condensate drain, tighten electrical connections, measure voltage and amperage on motors, lubricate moving parts.

Another solution may be to vent the attic space, if it is getting to hot up there and cool downstairs, that will cause humidity at the ceiling and  while your at it check the insulation in the attic, make sure there is enough to keep the temperature difference between the cooled space and the hot attic. hope one of these helps you.