Document Ev46j2bbjVwopVnbrQV7aMgN4

American Society oj Heating and Ventilating Engineers Guid 193J , 4. DAIRY BARN VENTILATION ;l The following are the salient requirements of dairy barn venfii '3; 1. For good ventilation, there should be provided about 3,500 cu. ft of ef nai latio*ij.* hour per 1,000 lb. of live stock weight. ' res" a'r 2. A strong convective circulation is generated by the heat from the bod' * stock, causing an upward movement toward the ceiling, about them, and aim ^ downward movement at the walls. ' COnsequai$ 3. Intake openings should be located in the walls near the ceiling so that i cold air, falling toward the floor, will accentuate the convective action inH/.i-Jj?*'1? heat within. sauced by the -- ' 20 30 40 SO ' b * TO BO SO \00. 5cole B Temperature Difference on the Two Sides of Window -- Decrees Rihrenheit Fig. 2. Saturation Curves showing Relationship between Relative Humidity , and Temperature Difference for Single, Double and Triple Windows 4. Outlet openings seem to function merely as exhaust ports, to relieve the interior pressure, and appear to have little influence on the direction of air currents. Hence, the spacing or distribution of outlet openings is rather immaterial, so long as the required athgagnreignatatekea.rea is provided. Area of outlet openings should be about one-third greater 5. It is better to take the air out at the floor than at the ceiling, since by the former there appears to be a larger volume of warm air held in the stable, which contributes to better temperature control. 6. The active circulation resulting from the down-flowing cold air entering at open ings in the walls near the ceiling, cooperating with the convective action induced by the heat of the animals, effectually prevents condensation and keeps the air fresh and odorless. 5. GOVERNMENT BUILDINGS (MECHANICAL EQUIPMENT FOR) The Guide, 1929, contains a chapter on this subject by N. S. Thompson of the Treasury Department. It contains data on the proportioning of 528 33--Special Applications of Heating and Ventilation fixtures, sewers, waua i------------- , --- 555m!Pg , approximations for determining the wattage for illumination, of elevators and the amount of heating surface in radiators. - ~en COVering the average fuel and labor and maintenance costs TapR1. 1. ,qq Treasury Department Buildings. The following is quoted Hp?ut i> gtronU Sfo lb. of coal per cubic foot is required per year for heating the ordinary gougno'.'in buildings containing electric generating plants 1 lb. of coal per cubic =,.^'. w<1virnately correct for all purposes. Roughly, the maximum electrical demand toe buildings averages k.w. per square foot of gross floor area. ^ tjniler [gom repairs allow $2.00 per horsepower nominal rating. f-^Pljigine room repairs allow $2.00 per annum per kilowatt total nominal rating rr^xiiler and engine room supplies allow $2.00 per annum per horsepower of boilers jjji&r; room labor averages $2.00 per ton of coal fired, based on an 8 hour shift and h"Aolsuhrrsempeorvwael eakv.erages H of a cubic yard to each ton of coal burned and is estimated tonsil $1.00 per cubic yard to remove it. The'labor in a Federal Building containing an electric generating plant will roughly average the same as the cost of the coal, supplies and repairs to the boilers and electric G~e3nfehreatofirxse. d charges for machinery in a Federal Building are 3 per cent interest and Fhlr'cent depreciation per annum on engines, boilers, etc., while on buildings, tunnels, S&? per cent depreciation per annum is allowed. ^rTlje annual dividend which must be earned by the ordinary isolated Federal plant in cdinparison with the purchase of current from a public utility company is 10 per cent on5tlil*cost of the Government plant. 6. GREENHOUSE HEATING 'liSsItus important that the heat shall be diffused evenly, that there shall high-velocity air currents, especially for flowers, and that no rapid 'temperature fluctuation shall be permitted. ; .gfcSfeam and hot water systems both are used in greenhouse heating. IS'Efeptrically propelled unit heaters have been used with good results. Jjnfortunate results occasionally are encountered with all of these dif ferent kinds of apparatuses. pliable 1 gives the usual temperatures required in greenhouses. The heat-losses from greenhouses are computed the same as are the heat -dosses from other types of building. The service is for 24 hours per j|jay, and the peak demand occurs when the weather is cold and there J|jsfnb sunshine, as at night. Leakage of air through cracks in the glass j^^'jfrfmes is not serious since in cold weather these freeze due to condensa- anc^ sea^ lightly with ice. The boiler in a greenhouse must always ^"l&bp'sflected on the basis of the heat demand and will seem large in pro^.,Jpcirtion to the square feet of radiation, since greenhouse radiators or ^ghphvectors usually are highly efficient. The piping, where direct heaters ,,a|.Jare used, is designed usually with a view to the kind of plants to be grown, *^ere *s sorne tendency to use side wall and free hanging overhead -^^mating surface in preference to piping under the plant benches. --r;. It is probable that there are more low-pressure steam heating systems gmr greenhouses than any other kind of system. It is highly desirable 529