thermal mass 2

Table 2: Values of coefficients of thermal transmittance for different wall materials and combinations in kcal/hm²C° (after Fathy 1986). These values need recalculating in W/m²K.

Type of Masonry	Wall Thickness (m)
	0.30	0.40	0.50	0.60	0.70	0.80	0.90
Limestone masonry:
External wall plastered on exterior	2.40	2.00	1.80	1.60	1.45	1.33	1.22
External wall plastered on both sides	2.30	2.00	1.80	1.60	1.41	1.30	1.19
Internal wall plastered on both sides	1.90	1.70	1.50	1.37	1.25	1.16	1.08
Dense stone, including marble and granite:
External wall plastered on exterior	2.90	2.60	2.40	2.20	2.00	1.90	1.70
External wall plastered on both sides	2.80	2.50	2.30	2.10	1.90	1.80	1.70
Internal wall plastered on both sides	2.20	2.00	1.90	1.80	1.60	1.50	1.45
	Wall Thickness (m)
	0.05	0.10	0.15	0.20	0.30	0.40	0.50
Concrete masonry (gravel, cement, and sand):
External wall without plaster	4.20	3.60	3.10	2.70	2.20	1.80	1.60
Internal wall without plaster	3.10	2.70	2.40	2.20	1.80	1.60	1.36
External wall plastered on both sides	3.50	3.00	2.70	2.40	2.00	1.70	1.44
Internal wall plastered on both sides	2.70	2.40	2.20	2.00	1.70	1.44	1.27
	Wall Thickness (m)
	0.12	0.25	0.38	0.51	0.64	0.77	0.90
Red brick:
External wall plastered on exterior	2.60	1.80	1.37	1.11	0.93	0.80	0.70
External wall on both sides	2.50	1.70	1.34	1.09	0.91	0.79	0.69
External wall plastered on interior	1.90	1.33	1.04	0.85	0.71	0.62	0.55
Light concrete block:
External wall plastered on both sides	2.00	1.25	0.93	0.73	0.60	...	...
Internal wall plastered on both sides	1.70	1.12	0.85	0.68	0.57	...	...
Sand-lime brick:
External wall plastered on exterior	2.90	2.00	1.60	1.27	1.08	0.93	0.82
External wall plastered on both sides	2.70	1.90	1.50	1.23	1.05	0.91	0.81
Internal wall plastered on both sides	2.10	1.60	1.24	1.03	0.89	0.78	0.69
	Wall Thickness (m)
	0.12	0.25	0.38	0.51	0.64	0.77	0.90
Red-brick double wall plastered on both sides with 5-12 cm cavity	. . .	1.38	1.11	0.93	0.81	0.70	0.63
Ordinary red-brick wall insulated with cork sheeting on internal wall only for insulation:
2-cm thick insulation	1.11	0.93	0.80	0.70	0.63	0.57	0.52
5-cm thick insulation	0.61	0.55	0.50	0.46	0.43	0.40	0.37
10-cm thick insulation	0.34	0.33	0.31	0.29	0.28	0.27	0.25

Note: 1.3 W/m²K (watts per square metre per Kelvin) is approximately 1.1 kcal/hm²C° or 0.225 Btu/hft²F°. One W/m²K equals approximately 0.85 kcal/hm²C°. One kcal/hm²C° equals approximately 1.17 W/m²K.

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thermal mass 2