DOE-2 Reference Manual Version 2.1 - DOE2.com

D. SIMULATION METHODOLOGY1. System Design CalculationsThe following explains how the SYSTEMS simulator utilizes the user-specifieddata (plus data from LOADS) to first size the HVAC equipment and then tosimulate the performance of the system.There are many ways that the system equipment slzlng can be performed bythe program in conjunction with the user, but all the available methods fallbetween two extremes:a) at one end of this sizing spectrum, the user supplies to SYSTEMS aminimum amount of data and then allows SYSTEMS to size the equipmentand simulate the behavior of the system. In this approach, the usersupplies values for only the required (mandatory) commands and keywords.The SYSTEMS design routine supplies all the missing values (by default).Of course, there are some keywords that are optional and have no defaultvalues. These keywords will be ignored and the associated optionalfeatures for the HVAC system will be missing. In this mode of operationthe design routine has the most freedom of design.b) at the opPosite end of the sizing spectrum the user supplies the maximumamount of data, thus restricting the use of default values. In thlSapproach, the user is limiting the freedom of the sizing routine. Itis very important for the user to realize that all keywords are not ofequal importance or priority. Some keywords have a greater effect thanother keywords in restricting the freedom of the SYSTEMS design routine.Unless the user understands the effect and/or priority of each keywordin SYSTEMS, the system being simulated mayor may not be that intendedby the user.All other equipment sizing approaches lie between extreme a) and extremeb). As the user supplies more and more values for optional keywords, thesizing method moves from a) toward b). Most users will elect to use someintermediate method. The SYSTEMS design routine permits the user to supplythose parameters which are deemed important to the user and the routineprovides the rest from its design strategy. It is therefore necessary for theuser to understand the design strategy built into SYSTEMS. In this sectionthat strategy will be described, along with suggestions of how the user mayoverride the strategy, should that be deemed necessary. The results of thiscooperative interaction between the user and the design routine are shown inthe VERIFICATION report, SV-A.To size a heating/cooling system, the following quantities must bedetermined:a. the maximum quantity of air supplied to each zoneb. the minimum amount of outside (ventilation) air required by each zonec. the maximum and minimum air temperatures of each zoneIV.298 (Revised 5/81)