David Thomas wrote:@ Holly: Yeah that's kinda what I'm wanting to figure out.
I hear so much about cob being a thermal mass and holding heat. I imagine that it would hold the cold in as well if set up correctly. I have no cob experience, just hoping those that do can shed more light on the matter.
Thermal mass will hold 'cool' the same as heat. It will tend to average out somewhere between the midday highs and overnight lows. So, if you're overnight lows are still uncomfortably hot for you, thermal mass alone isn't going to help you much.
A few feet underground, the temperature will tend to average out between annual mid-summer high air temps and annual midwinter low temps - that's a significant source of cool to tap into. Cool doesn't radiate like heat does, so you are mostly left with convection or conduction as the natural ways to move that cool around without expending energy.
Earthen, stone or tile floors can suck heat out of your feet by conduction, which can make a surprising difference even when air in the house is warm.
Proper passive design is doubly essential with earthen building. In warmer climates, wide roof overhangs keep the sun off the thermal mass walls. As mentioned above, shade trees are really helpful too.