DOE-2 Reference Manual Version 2.1 - DOE2.com

daily, and weekly operating schedules; four types of variable-volume fan controls;and constant, scheduled, or reset setpoints for supply air temperature.In addition, baseboard heating convectors can be used in combination with anyof the central-fan air-side systems.As an additional option, commercial and residential heat pumps can beassisted by a solar energy system. This support is described in theIntroduction of Sec. C, Chap. V.Other system combinations of component and control options can be simulatedif the thermodynamic processes are the same as those specifically modeledby the program. For example, a dual-duct or mu1tizone system with a coolingcoil installed upstream of the supply fan, rather than in the cold duct, isthermodynamically the same as a reheat fan system, and can be modeled as such.4. Calculation Proceduresa. System Sizing Calculations. The heat extraction/addition capabilityand air flow rates of the system may be assigned, if known (i .e., anexisting system). If these quantities are not entered, the programwill calculate them, based on design supply air temperatures and peakcooling/heating requirements. Alternatively, it may be desired tosize the system for "design day" rather than peak conditions. Toaccomplish this, the user inputs design outdoor weather conditions(in LOADS) and the program generates 24-hour weather data for summerand/or winter design days. (See DESIGN-DAY in Chap. III for adiscussion of the user input data required.) A SYSTEMS run usingdesign-day LOADS output will yield the desired sizing information.Design calculations are accomplished by the subroutine, DESIGN.subroutine is described in detail in the DOE-2 Engineers Manual.methodology used is discussed in Sec. D of this chapter.TheTheb. Calculation of Heat Extraction/Addition Rate and Room Temperature.Instantaneous heat gains/losses and room cool ing/heating loads arecalculated by the LOADS program, using response factors and roomweighting factors described in Ref. 1, Chap. XI. These loads arecalculated on the basis of a constant air temperature in the space.The actual air temperature generally deviates from the referencevalue because of cooling/heating equipment characteristics andoperating schedule and thermostat setback. Thus, heat extractionfrom the space will differ from cooling load, and heat- addition tothe space will differ from heating load. The final step in the calculationprocess, calculation of actual room temperature and heatextraction/addition rate, is accomplished by the SYSTEMS program withthe algorithms, described in Ref. 2, Chap. XI. The previously calculatedloads (from LOADS) are the input, along with the characteristicsof the air-conditioning equipment and the thermal characteristics ofthe zone. Heat extraction or addition rate and air temperature arethe output of SYSTEMS.I V. 3 (Revised 5/81)