Page 352 - Handbook of Energy Engineering Calculations

As a rule of thumb for thermal-storage wall systems, provide a minimum
3
3
of 1 ft (0.30 m ) of dark-colored thermal storage material per square foot
3
3
(meter) of collector for masonry walls or 0.5 ft (0.15 m ) of water per square
foot (meter) of collector for a water wall. This will provide enough thermal
storage material to maintain the inside space temperature fluctuation within

15°F (8.33°C).

6. Determine the surface area of storage material for a direct-gain space
In a direct-gain system, the insolation must be spread over the surface area of
the storage material to prevent overheating. Generally, the larger the surface
area of material, the lower the inside temperature fluctuation, and thus the

space is more comfortable. To determine this area, enter Fig. 15 at the lower
axis to select an acceptable space temperature fluctuation. Project vertically
to the curve, and read left to the A /A ratio. This is the ratio of thermal
S
C
storage material surface to collector area, where A = surface of storage
S
2
2
material receiving direct, diffused or reflected insolation, ft (m ). In this
example, 15°F (8.33°C) is selected, requiring A /A = 6.8. Thus, A = (6.8)
S
C
S
2
2
(42) = 286 ft (26.5 m ).
This step is not required for the design of thermal-storage wall systems in
which A = A .
S
C