DOE-2 Reference Manual Version 2.1 - DOE2.com

NEUTRAL-ZONE-HTshould be assigned a value when the crack method is used tocalculate infiltration (see table under INF-METHOD). It isused to compute a pressure difference between the inside andoutside of a tall building caused by the "stack effect" orair density gradient. The calculated pressure difference isadded to the pressure difference caused by wind velocity.The value to be entered is calculated as follows. Let NPL(neutral pressure level) be the line on the buildingexterior where the pressure difference between the insideand outside resulting solely from the stack effect equalszero. The height of the NPL 1 ine is typically one-half thebuilding height. The entry for the NEUTRAL-ZONE-HT keywordis the distance, in feet, from the center of the exteriorwall of the space under consideration to the NPL line. Thisdistance is positive if the space is below the NPL line andnegative if the space is above the NPL 1 ine. Figure III.15,a modified version of Fig. 4 in Chap. 21 of Ref. 5, furtherexplains this keyword entry.If the SPACE-MULTIPLIER keyword of the SPACE instruction isused for spaces located on different floors, the valueentered for NEUTRAL-ZONE-HT shoul d be the average NEUTRAL­ZONE-HT for all the spaces. In general, NEUTRAL-ZONE-HTshould be entered in the SPACE instruction, since it will bedifferent for each space.FLOOR-WE IGHTis used to specify the compos ite wei ght of the floor,furnishings, and interior walls of a space divided by thefloor area of the space. The value input by the user wiildetermine the weighting factors associated with the SPACE.ooE-2 has two types of weighting factors, PrecalculatedWeighting Factors and Custom Weighting Factors.Precalculated Weighting Factors:If the user specifies FLOOR-WEIGHT = 30., 70., or 130.,standard, precalculated ASHRAE weighting factors are usedthat represent respectively light, medium, and heavy construction.If values other than these three are input, DOE-2interpolates between the ASHRAE weighting factors. At FLOOR­WEIGHTs less than .1 lb/ft2 and greater than 200 lb/ft2,the extrapolation of weighting factors is unreliable.If an exterior wall is uninsulated or is insulated on itsoutside surface, the entire mass of the wall Should beincluded in the composite weight. The composite weight isused to adjust the internal heat capacitance of the Iluildingand, hence, affects the transient thermal load calculationsfor the building.III.51 (Rev ised 5/81)