A solar home will overheat if the proper ratio of glass to floor & wall mass ratio is not properly balanced. If approximately 7% of the floor & wall mass area is used as glass area the wall & floor mass will absorb the heat gain. When glazing exceeds the 7%, additional mass is required or the house will overheat on sunny days. It's important to follow the three glass-to-mass ratios.

The first ratio relates solar glazing to floor mass in direct contact with sun­ light.
In such cases, each square foot of solar glazing over the 7 percent mark requires 5.5 square feet of uncovered and sunlit (directly illuminated) floor mass.

The second ratio relates solar glazing to floor mass not in direct contact with incoming solar radiation, but in the same room. In this case, 40 square feet of uncovered and "unlit" mass accommodate one square foot of solar glazing. (The efficiency of floor mass falls off dramatically when it is covered by carpeting.)

The third ratio relates solar glazing to wall mass.
In a room being warmed directly by sunlight, you'll need 8.3 square feet of wall mass for each square foot of solar glazing over the 7% mark.