Adobe structures do not maintain any temperature. They lag the outside temperature change by a time period dependent on the thickness of the adobe. If designed right, the lag will be approximately 12 hours so that at noon you are getting the effects of the midnight temperatures, and the opposite. Adobe acts as a "thermal flywheel". There are times when the inside temperature is higher than the outside temperature. There are times when the inside and outside temperatures are equal. The inside temperature is not always 20% below ambient.
On 6/22/2012 8:16 AM, Forrest Charnock wrote:
Adobe structures typically maintain a temperature 20% below ambient in temperature. When it is 100 outside it will be approximately 80 inside. The structure I suggested will be a bit better if you use the thick stucco layers inside and , if possible outside. A double layer roof with aluminum underneath the first will reflect a great deal of the solar radiation. An 18" this insulation would be advisable for the roof. One of the beauties of the rice is it allows you a very thick roof at a fraction of the weight . Of course cellulose is even lighter but the cost goes way up. The roof is 80 percent of the summer heat load. In Austin I would use a dirt , cement , or tile floor with no insulation underneath. The advantage of using the heat sink of the earth in summer is greater than any loss in the short Central Texas winter. If 70 degrees is satisfactory that will take a very small a/c . If you don't know how to size them hire a pro because the trick is to build a system that runs continually. Often a multi-stage unit is most efficient. There are few things more important in the efficiency of cooling than the ac itself. The upfront cost is not the most important but long term efficiency. I had a house in Houston in the 80's that was built in 1911 and leaked badly. Similar houses in that neighborhood , Northside off North Main Street , had light bills of 250 to 300 in the summer. Mine never hit 100 because I had a carrier 3 stage . I paid 2 grand more than I had to but it was well worth the extra. If you need the 50 degrees you mentioned before you will need to get a pro to suggest the equipment. Finding a used unit to salvage the doors at least might be a good idea. A good a/c should give you 65 if it is sized correctly. On 6/21/12, highdesertpermaculture <christine@bayhouse.com> wrote:How do you intend to actually cool it? I know that basements can be kept at around 70 "or so", but above ground that'll take serious electricity. We're building a farmstand right now and I sure wish we could store fruit and veggie for sale. Christine --- In papercreters@yahoogroups.com, "brightsideatx" <farump@...> wrote:Howdy! I'm designing a new walk in cooler to be built via a workshop format for an urban farming non profit here in Austin, TX. I want to keep this thing at or below 50F year round but never frozen. It gets up to 110 here some days, and can be over 90 every day for six months at a time, sometimes humid, sometimes dry, sometimes thunder storms, and freezing maybe ten days a year. I started out thinking of using straw bale, but I'm concerned it would rot due to constant condensation in the bale wall. Then I thought earthbag, but apparently it's not very insulative unless you can fill it with volcanic scoria gravel which we do not have here. I'm going for a more eco friendly and cheaper option than shed with foam panels, so what do you think, is papercrete the thing to use? What is the optimal mix for insulating / structural walls? Is it feasible to pour a papercrete floor over some gravel and sand bags to insulate from the earth as well? Do you think it would be a moldy mess? This thing needs to be as cheap and easy to build as possible, any thoughts would be greatly appreciated. Thanks!
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