Earth Coupling
With all of the damage to homes in Texas I have to wonder what can be done going forward to frost proof homes there in a power outage. All water pipes should be on the room side. Here is an old GBA thread on “Earth Coupling”
https://www.greenbuildingadvisor.com/question/does-earth-coupling-work
There is a fair amount of heat stored in a concrete slab on grade and without sub slab insulation the Earth connection will add to the total. The surfaces inside of the thermal boundary, drywall, flooring, furniture also have stored heat. My home in Minneapolis is not a model of efficiency but I lose about 1 degree F per hour when the furnace sets back and the outdoor temperature is 0. I have determined the heat loss for this home to be 360 Btu per hour per degree F. If the power goes out this heat loss will slow because the Delta T is lowered as the indoor temperature drops. How many hours can I go before the indoor temperature hits 32F with the outdoor temperature at 0. I have a full basement, foundation wall interior R-10, no sub slab insulation. For simplicity let’s exclude solar gain in the equation.
I worked with a customer in Dallas, TX in 2005 I believe. They built a home to near Passive House levels, well insulated and very airtight. I would like to know how that home performed if power was lost there.
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I think Dana and Martin answered your slab question for the hot parts of Texas: insulate the perimeter with a termite resistant detail.
I spoke with friends in Dallas area this week. Their water shutoff valve is buried in the yard. They had to use a shovel to find it and pry the cover off. Not so great when water is shooting from the wall. The bigger problems are 1) water pipes in external walls 2) barely there insulation (a couple of tufts of pink batt), and 3) massive air leaks that became more obvious when they cut out drywall to do repairs.
IMO, adopting reasonably current codes and enforcing them would likely solve many of the freezing water problems. In particular, the 3 ACH50 requirement would help. But as Amando and many others from around the country have said, it's lack of enforcement that's key.