The use of Geothermal Mass will moderate the house around 15C (60F) however a quick review of St Johns winter temperatures show sub freezing temperatures at night for 6 Months of the year. So we need thermal mass that will release heat faster and at higher temperatures at night. 

Structural mass is usually expensive to include in buildings, however White Horse Mesa has an abundance of rock. Most structural and internal walls will be constructed using 'slip form' and therefore introduce thermal mass into the house.

The primary heat collectors, the floors will use two other techniques:-

1. Thermal Slab
2. Inertia timber beams.