modulus of rupture strength of at least 50 lbf/in2 (0.345 newton/mm2) for the finished block. In addition to being an inexpensive material with a small resource cost, adobe can serve as a significant heat reservoir due to the thermal properties inherent in the massive walls typical in adobe construction. In climates typified by hot days and cool nights, the high thermal mass of adobe mediates the high and low temperatures of the day, moderating the temperature of the living space. The massive walls require a large and relatively long input of heat from the sun (radiation) and from the surrounding air (convection) before they warm through to the interior. After the sun sets and the temperature drops, the warm wall will continue to transfer heat to the interior for several hours due to the time-lag effect. Thus, a well-planned adobe wall of the appropriate thickness is very effective at controlling inside temperature through the wide daily fluctuations typical of desert climates, a factor which has contributed to its longevity as a building material. Thermodynamic material properties have significant variation in the literature. Some experiments suggest that the standard consideration of conductivity is not adequate for this material, as its main thermodynamic property is inertia, and conclude that experimental tests should be performed over a longer period of time than usual - preferably with changing thermal jumps. There is an effective R-value for a north facing 10-in wall of R0=10 hr ft2 °F/Btu, which corresponds to thermal conductivity k=10 in x 1 ft/12 in /R0=0.33 Btu/(hr ft °F) or 0.57 W/(m K) in agreement with the thermal conductivity reported from another source. To determine the total R-value of a wall, scale R0 by the thickness of the wall in inches. The thermal resistance of adobe is also stated as an R-value for a 10-inch wall R0=4.1 hr ft2 °F/Btu. Another source provides the following properties: conductivity=0.30 Btu/(hr ft °F) or 0.52 W/(m K); specific heat capacity=0.24 Btu/(lb °F) or 1 kJ/(kg K) and density=106 lb/ft3 or 1700 kg/m3, giving heat capacity=25.4 Btu/(ft3 °F) or 1700 kJ/(m3 K). Using the average value of the thermal conductivity as k = 32 Btu/(hr ft °F) or 0.55 W/(m K), the thermal diffusivity is calculated to be 0.013 ft2/h or 3.3x10−7 m2/s. Uses Poured and puddled adobe walls Poured and puddled adobe (puddled clay, piled earth), today called cob, is made by placing soft adobe