Book - School of Science and Technology

Capacity of room stores 123Table 5.2Correction factors `Z ' for building typeCorrection factors `Z' for following levels of design heat loss (W/m 2 )Mean 24 hour heat gains (W/m 2 ) 904 0.55 0.70 0.75 0.80 0.908 0.45 0.60 0.70 0.75 0.8012 ± a 0.50 0.60 0.70 0.7016 ± a ± a 0.45 0.55 0.60Domestic 0.75 0.80 0.85 0.90 0.95Notesa Premises not suitable for heating by storage methods.1. Where windows are smaller than average, reduce by 0.05.2. where windows are larger than average, increase by 0.05.Table 5.3 Correction factors `Y ' for night/day consumptionProportion of annual energy consumption used off-peak (%)All 99 98 97 96 9594 93 92 91 90Correction factor `Y 'for design day rating 1.0 0.9 0.85 0.81 0.79 0.76 0.74 0.72 0.70 0.68 0.67. The order of design heat loss, the proportion of glazing, the thermal mass ofthe building structure and the level of heat gain from lighting and occupants. Theseare dealt with by what are called `Z' factors, a digest of which is set out in Table 5.2.. The proportion of design heat requirements to be met from storage in order to achievea selected seasonal level of energy used at off-peak rates. This is dealt with by what arecalled `Y ' factors as listed in Table 5.3.Capacity of room storesStorage radiatorsFor these, the simplest of the various types of equipment available, the required rating(R 2 ) is determined generally from the basic calculation noted above by use of the correctionfactor `Z' alone, such that:R 2 ˆ ZR 1whereZ ˆ factor from Table 5:2To take account of those applications where it is accepted that some direct on-peakheaters will be fitted in parallel with the storage radiators, use is made also of thecorrection factor `Y ' such that the required capacity dealt with by storage (R 3 ) will be: