Document JN0ENVxmBpJ4G0mm1DxMe0G72

American Society of Heating and Ventilating Engineers Guide, 1930 the pipe transmission losses may be considerable. Where the heating plant is located within the building to be heated, the house or building efficiencies for coal, oil and gas may be substantially higher than those specified, although it is even possible that the efficiencies may be lower than these values under,varying conditions of operation. Radiation Saving: The installation of a given thickness of insulation in the walls and/or roof of a building will reduce the amount of direct radiation required to maintain the desired temperature, and in many cases this may be an item of considerable importance; in fact, in the case of certain uninsulated constructions having a high rate of heat trans mission, the monetary value of the saving in radiation due to the applica tion of the insulation, may be sufficient to offset the cost of the insulation. The amount of radiation that can be saved is of course determined from the difference in the radiation requirements of the uninsulated and insu lated buildings. The radiation saving can also be estimated by means of the following formula, if a steam heating system is to be installed : where ,, (U- Ui) X -<,,) X A K-------------- -------- oTn----------------- R$ = saving in square of equivalent radiation based on a steam heating system. to -- the outside temperature on which the design of the system is based. (15) If in the example on page 32, the temperature lQ is 0 deg. fahr., the , saving in radiation for a steam heating system will be: D _ (0.25 - 0.15) X (75 - 0) X 10,000 240 == 312 sq. ft. of equivalent direct radiation. If the allowance on the reduction in the radiation required for this building on the above basis is $1.00 per square foot, the monetary value of the radiation saving will be $312.00, which if credited to the insulation, will leave a net cost of the insulation of $0.11 X 10,000 or $1,100.00 minus $312.00 or $788.00, and the annual return on the investment,- taking both the fuel and radiation savings into consideration, will be .m ^ $10.00 X 14.3 . 1C . ' .. , 100 X ---- $788 00-- per cent, neglecting insurance and dev v preciation. The radiation saving for a hot water or vapor system can be estimated by substituting the proper heat emission factor in the denominator of equation (15) for the value of 240 for steam. This heat emission factor1 varies with the heat dissipation coefficient of the radiator and the tem perature difference between the medium in the radiator and the air surrounding it and is about 160 for hot water. However, it is obvious that the same factor should be used for estimating the radiation saving with insulation as was used for designing the heating system. 34 Chapter 2--Heat Losses from Buildings Table 12. Coefficients of Transmission (U) of Solid Brick Walls'! , ___These coefficients are expressed in B.t.u. per hour per square foot per 1 dec. fahr. RENCE IN TEMPERATURE BETWEEN THE AIR ON THE TWO SIDES AND ARE BASED ON AN OUTSIDE WIND SniK OF 15 MILES PER HOUR. -n,e values of U in this-Table are based on the following Ll-rmal Conductivities or Conductances which are e,pre,sed m *t.u.per Mr. perS^. per CF ^ Cement Mortar Plasterboard piaster (Gypsum) -? P*r'. 3.13 per* Z,Z per 1 Wood Loth 4 Plaster Z.00 as applied Cork board Pcr r Eiaid Insulation (Boardform) 0.3$ perl" Cellular Gypsurr (18* ) sqa P-'. flaked Gypsum, Dr^CZA*) _ 0.46 per 1 Split FurrinqTile It l 40 Z"* 115 Y= Thickness of Insulation where specified 1 Interior Construction 1 Plain'Walls -hlo Interior Finish 2. Plaster on Brick. 3 5" Plaster on Metal Lakh - Furred 4 i' Plaster on Wood Lath - Furred 5 j Plaster on ^ Plaster board-Furred jf Plaster on Wood Loth on 2" Purnnq <0 Strips-Cellujar Gypsum Fill c 5 Plaster on Wood Lath on 2T Furrinq 7 Sknps - Flaked Gypsum Fill 8 * Plaster on (2tqid Insulation (Board form) Purred 10 *j Plaster on Corkboard Cement Mortar II in - * Plaster on 1V Split Fumnq Tile set 11 aqainst Wall Plaster on 2" Split Fumnq Tile set 13 aqainst Wall Thickness of Brick -X V & iz* Kb* AB C 0.385 0.285 0.238 0.35b 0.277 0.261 0.216 0.250 0.208 0.251 a if 0. 171- a 'I' 0.154 0.208 0.151 0.137 ri 0.181 . 0.166 r 0.148 0.132 if 0.127 0.115 2" 0.105 0.087 0.284 0,231 0.227 0-184 0.178 0.178 0.135 0.124 0.146 0-120 0-104 0.080 0.185 0.277 0.227 0,1.82 Based on in., the actual thickness of 2 in. furring strips. fcThe coefficients on this page can also be used with sufficient accuracy for the Ideal Rolok-Bak Wall. cThe coefficient used for cellular gypsum, 0.59 is for 18 lb. weight--weights as low as 12 lb. may be used* 35