In areas where the soil routinely freezes it is essential that building foundations, conduits, and the like be buried below the frost level. Central Minnesota is a cold part of the US with yearly average temperature of T₀ ∼ 5 ^◦C and variation ΔT ∼ 20 ^◦C. Typical peaty soils in this region have thermal diffusivity a ∼ 1.0×10⁻⁷ m²/s. Building regulations require foundation footings to exceed a depth of 1.5m. Do you think this is adequate?