Quote:
Originally Posted by Cole_Robbie
Mass can store cold, too, as well as heat. That's why the mass concept does not mix well with paying for heat. In the morning, when the mass is cool, the heat has to run more than if there was no mass at all.
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Cold is just the absence of heat and I guess, the capacity to store it. That depends on the material in question and how readily it is heated and gives off its heat. Small sealed containers of water for example, will rapidly come to equilibrium with the air temperature, compared with stone or earth which warm and cool really slowly. The storage mass in my stone floor in the greenhouse gets deeply heated during the summer months and this continues to moderate temperatures in fall and winter, but our winter is long and so by spring there is little or no stored heat left to warm the air at night. The same goes for the earth in my friend's greenhouse. The surface warms quickly. We wait for the ground to warm deeply enough to plant tomatoes. I have dug planting holes in May only to find the ground really chilly at the bottom of the hole.
Meanwhile the coldness of stone floor or the soil at depth does not affect air temperature afaict, nor how fast the air warms when the sun is shining.
I guess I can't get my head around the idea that it would cost more to heat when using passive storage mass. It makes no sense to me. The heat it absorbs is gratuitous, a bonus on heating the air. I think so? Which reduces the need for heat overall.