Document b5gmgYZJ74ne8EqzeR8bZ0Bpy

Ij Heating Ventilating Air Conditioning Guide 1939 Chapter 12. ' Heat and Fuel Utilization. . records to be sure that they do not include energy or fuel used for other purposes than heating the building. Estimates based on computed heat losses alone are frequently the only ones possible to obtain especially where new equipment is put int0 unusual buildings and there is a scarcity of records and an absence of experience data. Such estimates also have to be made where direct information is not obtainable as, for example, if a survey is being made without the assistance or knowledge of the building operator and thus without information as to the'kctual consumption. Estimates of this kind are also useful in some cases where a relative standard of performance is desired to serve as a base of comparisons in a campaign of fuel utilj. CALCULATED HEAT LOSS METHOD This method is theoretical and assumes constant temperatures for very A finite hours each day throughout the entire heating season. It does not ke into account factors which are difficult to evaluate such as opening of windows, abnormal heating of the building, sun effect, poor heating systems, and many others. In order to apply this method the hourly heat loss from the building nder maximum load, or design condition is computed following the ' 5GROSS OUTPUT-THOUSAND 6 T.UPER HOUR GROSS OUTPUT - HUNORED FEET STEAM RADIATION . ri i i i | T1 i l l'l l l"'l--I `1 1 l '"1--r I I | 1 s to - 5 20 25 GROSS OUTPUT HUNDRED FEET WATER RAOIATION Fig. 1. Coal Fuel Burning Rate Chart "i i i 30 zation. In such situations it can be plausibly argued that an estimate based on computed heat quantities is to be preferred to one which is related to operating methods. ' In interpreting and evaluating heat or fuel consumption estimates'as well as in their preparation, it is well to realize that any estimating method used will produce a more reliable result over a long period operation than over a short period. Nearly all of the methods in common use will give trustworthy results over a full annual heating season, and in some cases such estimates will prove consistent within themselves for monthly periods. As the period of the estimate is shortened there is more chance that some factor not allowed for in the estimating method will become controlling and thus give discrepant and even ridiculous results. Of the various estimating methods in use attention is directed in this discussion to but two as they are illustrative of all, viz: (1) calculated heat loss method, and (2) degree-day method. 234. -1-------- 1-------n-------- 1---------1---------1---------1 l I rr I i I ^ r~ o 2 4 6 8 10 12 14 IS GROSS OUTPUT - HUNDRED FEET STEAM RAOIATION --1--p--i--1--i--I--TT--I--i--i--i--i--i--I--i--i--I--I--i--i--i--r o 5 10 15 20 25 GROSS OUTPUT - HUNDRED FEET WATER RADIATION Fig. 2. Oil Fuel Burning Rate Chart51 This chart is based upon No. 3 oil having a beat content of 143,400 Btu per gallon. If other grades of oil are used multiply the value obtained from this chart by the following factors: No. 1 oil (139,000 Btu per gallon) i'.u32; No. 2 oil (141.000 Btu per gallon) 1.017; No. 4 oil (144.500 Btu per gallon) 0.992; No. 5 oil (146,000 Btu per gallon) 0.982; and No. 6 oil (150,000 Btu per gallon) 0.956. principles discussed in Chapters 5 and 6 and the method described and illustrated in Chapter 7. In some cases, however, depending on the presence of interior par titions, the computed heat loss is modified when used for estimating the heat or fuel consumption. If the building has no interior walls or par titions then, by the method of Chapters 6 and 7, the infiltration losses are calculated by using only half the total window crack. In such a building the calculated loss need not be modified in order to prepare heat or fuel estimates by this method. Where the building'does contain interior walls or partitions instead of using as the calculated heat loss (IT) which is equal to the sum of the transmission losses (Ht) and the infiltration losses (H{), it is more desirable to let H = Ht + Jd 235