Document emKOgKgp2jK9bY7N9B69vOXr4

1950 Guide Cooling Load 275 Table 15--Concluded. Total Equivalent Tbmpebatube Differentials foe Calculating Heat Gain Thbough Sunlit and Shaded Walls Sun Time Nobth Latitude Wall Facing BE S sw NW N (Shade) A.M. P.M. 8 810 13 2 4 10 Exterior color of Wall--> dark, L = ight 12 1 D L D 1 DD - D L D 12 In. Concrete on Stone DLD1 6 4 6 2 6 2 14 8 14 8 10 8 10 8 12 10 10 8 10 6 8 6 10 6 18 10 18 12 16 10 12 10 14 10 14 10 8 4 8 4 6 4 14 8 16 10 16 10 14 10 12 10 13 10 6 4 4 2 4 2 4 2 10 6 14 10 16 12 14 10 10 8 8 4 8 4 6 4 6 4 8 6 10 8 18 14 20 14 18 12 1(1 e 8 8 8 6 10 6 10 6 12 8 16 10 24 14 22 14 6 4 6 2 6 2 6 4 6 4 8 6 1(1 8 18 12 20 14 0 0 0 0 0 0002244668866 South Latitude Wall Facing BE E NE N NW W SW S (Shade) NOTES FOR TABLE 15 Explanation: Total beat transmission from solar radiation and temperature difference between outside and room air Btu per (hr) (sq ft wall area) Equivalent temperature differential from above table X Heat transmission' coefficient for-wall Btu per (hr) (sqi ft) (F deg) NOTES: 1. SOURCE. Same as Table 14. A north wall has been assumed to be a wall in the shade; this is practi cally true. Dark colors on exterior surface of walls have been assumed to absorb 90 per cent of solar radiation fnd reflect 10 per oent; white colors absorb 50 per cent and reflect 50 per cent. This includes some allowance for dust and dirt since clean, fresh white paint normally absorhs only 40 per cent of solar radiation. 2. APPLICATION. These values may be used for all normal air conditioning estimates, usually with out corrections, when the load is calculated for the hottest weather. Correction for latitude (Note 3) is neces sary only where extreme accuracy is required. There may be jobs where the indoor room temperature is considerably above or below 80 F or where the outdoor design temperature is considerably above 95 F, in which case it may be desirable to make correction to the temperature differentials shown. The solar intensity on all walls other than east and west varies considerably with time of year. 3. CORRECTIONS. Outdoor minus room temperature. If the outdoor maximum design -temperature minus room temperature is different from the base of 15 deg, correct as follows. When the difference la greater (or less) than 25 deg add the excess to (or subtract the deficiency from) the above differentials. Outdoor daily range temperature. If the daily range of temperature is less than 20 deg add 1 deg to every 2 deg lower daily range; if the daily range is greater than 20 deg, subtract 1 deg for every 2 deg.higher daddy range. For example, the daily range in Miami, Florida is 12 deg, or 8 deg less wan 30 deg; therefore, the cor rection is-+ 4 deg. Color of exterior surface of wall. Use temperature differentials for light walls only where the permanence' of the light wall is established by experience. For cream colors use the values for.light walls. For medium colors interpolate half way between the dark and light values. Medium colors are medium blue, medium. green, blight red, light brown, unpainted wood, natural oolor concrete, etc. Dark blue, red, brown, green, etc., are considered dark colors. For latitudes other than 40 deg north; and n other months. These table values will be approximately correct for the east or west wall in any latitude (0 deg to 50 deg North or South) during the hottest weather. In the lower latitudes when the maximum solar altitude is approximately 80 deg to IK) deg (the maximum occurs at noon) the temperature differential for either a south or north wall will be approximately the uni> as a north, or shade wall. The temperature differential (fx) for any wall facing, and for any latitude for any month may be approximated ss follows: whsrs U " t1e5m. perature differential for the same wall in shade for desired time of day; obtained from Table It a maximum solar radiation intensity transmitted through glass, Btu per (hr) (sq ft) for particular wall facing, in July, 40 deg north latitude {note: this is maximum value irrespective of time). I* m same as It exoept use the maximum value for wall faming, for month, and latitude desired for tx. tw " temperature differential far particular wall facing, for the desired time of day from above table. .. (Nots that this makes adjustment only for solar radiation and that there map be additional correction 'for outdoor temperature.) 4. FOR INSULATED WALLS use *nw temperature differentials as used for nningiiUtii walls.