Book - School of Science and Technology

Temperature difference 55Table 2.13 Values for temperature ratios F 1 and F 2System type and ventilation indexLoaded average U value AU/AType of heat emitter(per cent convective)Ventilationindex0:33 NV/A0.6 1.0 1.5 2.0F 1 F 2 F 1 F 2 F 1 F 2 F 1 F 2Forced warm air(100) All 0.97 1.10 0.95 1.16 0.92 1.23 0.90 1.30Natural convectors 0.1 0.97 1.08 0.96 1.13 0.93 1.20 0.91 1.26Convector radiators 0.2 0.97 1.08 0.96 1.13 0.94 1.19 0.92 1.25(90)0.3 0.97 1.07 0.96 1.12 0.94 1.19 0.92 1.250.6 0.98 1.07 0.96 1.12 0.94 1.18 0.92 1.241.0 0.98 1.06 0.96 1.11 0.94 1.17 0.92 1.23Multi-column radiators 0.1 0.98 1.06 0.96 1.11 0.95 1.16 0.93 1.21Block storage heaters 0.2 0.98 1.06 0.97 1.10 0.95 1.15 0.93 1.21(80)0.3 0.98 1.05 0.97 1.09 0.95 1.14 0.94 1.200.6 0.99 1.04 0.97 1.08 0.96 1.13 0.94 1.181.0 0.99 1.02 0.98 1.06 0.96 1.11 0.95 1.16Two-column radiators 0.1 0.98 1.05 0.97 1.08 0.96 1.12 0.95 1.16Multi-panel radiators 0.2 0.99 1.04 0.98 1.07 0.96 1.12 0.95 1.16(70)0.3 0.99 1.03 0.98 1.06 0.97 1.11 0.95 1.150.6 1.00 1.01 0.99 1.04 0.97 1.08 0.96 1.131.0 1.01 0.98 0.99 1.02 0.98 1.06 0.97 1.10Single panel radiators 0.1 1.00 1.01 0.99 1.03 0.98 1.05 0.98 1.07Embedded floor panels 0.2 1.00 1.00 0.99 1.02 0.99 1.04 0.98 1.06(50)0.3 1.01 0.99 1.00 1.00 1.00 1.02 0.99 1.040.6 1.02 0.95 1.01 0.97 1.00 0.99 1.00 1.011.0 1.03 0.91 1.02 0.93 1.02 0.95 1.01 0.96Ceiling panels 0.1 1.01 0.98 1.01 0.98 1.01 0.98 1.01 0.98Wall panels0.2 1.01 0.97 1.01 0.97 1.01 0.97 1.01 0.97(33)0.3 1.02 0.94 1.02 0.94 1.02 0.94 1.02 0.940.6 1.03 0.91 1.03 0.91 1.03 0.91 1.03 0.911.0 1.05 0.86 1.05 0.86 1.05 0.86 1.05 0.86High temperatureradiant heaters(10)0.1 1.02 0.94 1.03 0.92 1.04 0.89 1.05 0.860.2 1.03 0.92 1.03 0.90 1.04 0.87 1.05 0.840.3 1.04 0.90 1.04 0.88 1.05 0.85 1.06 0.820.6 1.05 0.85 1.06 0.83 1.07 0.80 1.08 0.771.0 1.07 0.79 1.08 0.76 1.09 0.74 1.10 0.71whereQ t = the total heat requirement, being the sum of conductionand infiltration losses (W)Q u ˆ the conduction loss, per kelvin (W/K)Q v ˆ the infiltration loss, per kelvin (W/K)ApplicationTake the same building which has been used in preceding examples, as insulated and withan infiltration rate of 1 1 ¤ 2 air changes per hour. The internal dry resultant temperature isto be 19 C with an external air temperature of 1 C. Heating is to be by single-panelradiators.