flaja wrote:I know from personal experience that thermal mass in Florida is not a good thing. I grew up in a house that had a wooden floor set on concrete block pillars. The house could get very cold and very hot, but it never took the ac or heater very long to make the house comfortable. But, I now live in a house that is on a concrete slab foundation. Since it takes so long for the slab to absorb or release heat I often have to have the ac running in October when outside temperatures are comfortable and I also have to have the heater on in May even though the outside temperatures have been reaching 90 degrees by the end of April.
gearweasle wrote:Two examples in my mind. They recommend in Minnesota, for enegy conservation, to put used milk jugs of water in your refridgerator, instead of having an empty refridgerator, to make it more efficient. That way the compressor doesn't kick so often, trying to keep the fridge at the proper
temperature. That's thermal mass.
flaja wrote:gearweasle wrote:Two examples in my mind. They recommend in Minnesota, for enegy conservation, to put used milk jugs of water in your refridgerator, instead of having an empty refridgerator, to make it more efficient. That way the compressor doesn't kick so often, trying to keep the fridge at the proper
temperature. That's thermal mass.
Did the compressor not have to run longer than it would have in the first place in order to cool the thermal mass?
flaja wrote:I now live in a house that is on a concrete slab foundation. Since it takes so long for the slab to absorb or release heat I often have to have the ac running in October when outside temperatures are comfortable
Insight Driver wrote:Consider just a box made of plywood. Next to it put an identical box, but coat the outside with 4" of polyurethane foam. Run an airconditioner in each box. Which one will use the most electricity? Clearly the one in the box without insulation. This is, in a highly-simplified form, the principal in a monolithic dome. It is a highly-insulated structure. Once the interior space is properly conditioned it takes much less energy to maintain that temperature because it is highly insulated from the outside temperature.
As far as a slab is concerned, it also must be properly insulated or it is just a large heatsink tied to the earth temperature. While it is common in northern climates to insulate the slab, I don't think it is common in Florida, so you end up with a slab that constantly sinks or sources heat, depending on whether it is warmer or cooler than the air inside the box you are trying to condition.
The example of the insulated chests is germain. An empty chest will not stay cold inside for as long a time as a chest full of ice because it takes a lot more energy leaking into the chest to bring the ice up to the outside temperature.
The insulation is key. The mass inside the monolithic dome soaks up the daily outside fluctuations in temperature that leak through the insulation. This means the air conditioner for the space inside does not have to cycle on and off as much as it would if it were just an insulated box without mass inside.
Basically all you have to do now, once the mass of a monolithic dome has been stabilized is to cool what heat the leaks through the insulation, but not having it change rapidly due to outside air temperature and insolation changes it just reacts to the slow change caused by the mass that is able to act as a sponge that holds heat energy.
hitssquad wrote:flaja wrote:I now live in a house that is on a concrete slab foundation. Since it takes so long for the slab to absorb or release heat I often have to have the ac running in October when outside temperatures are comfortable
There is something missing from your anecdote, and that is: what heat source made the slab uncomfortably hot and how would you have dealt with that heat source if the slab had not been soaking up the heat.
If the answer is approximately, "What made the slab uncomfortably hot was the sun streaming in through the windows during the day,
I time period when I wasn't home and therefore didn't have a concern for the house being too hot since I would have been easily -- without the slab -- able to cool the house off at night by simply opening the windows," perhaps the design of your southern-exposure window visor could stand improvement in such a way,
As for your school, I would design it without any windows at all. There would be less distractions that way for the students, and in case of an atmospheric overpressure event emanating from outside the students would not be impaled by millions of high-velocity glass shards.
Insight Driver wrote:A flat black surface absorbs radiant heat readily.
Missouri Dome Builder wrote::lol: My dome is north of I 70 in north Mo. It was my plan to run a small airconditioner only at night when the cooler outside air makes the ac more efficient. It also pays to put compressor in the shade. But guess what?? With my thermal mass it has never reached a temperature where the ac was needed. The warmest it has been is 74 dgrees. At that temperature a ceiling fan is enough to keep people comfortable. Note, that even with the largest outside temperature change, the inside temperature will not change more than a degree in one day. Some domes will change more than this and the reason is because of the mass of the thermal battery. I have 6" thick walls.
I feel sure the same idea would work in Florida. Only run the ac at night and the mass will keep the house cool through the day.
missouri dome builder
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