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Re: [EnergyPlus_Support] Cooling load in EnergyPlus not similar to RESFEN3.1
You are on the right track because infiltration is a significant part of heating and cooling loads. If you don't have any ventilation air now, you also don't have breathable air in the building for occupants. So a good rule of thumb is it would be good to have at least 15 cfm per occupant on average. Whether you have more or less for a particular building depends on climate, construction, and occupant habits.
I haven't read the details of RESFEN infiltration modeling, but I am generally familiar with Sherman's work and air infiltration testing. I think the infiltration model in Energy+ will get you most of the way there. Sherman's infiltration equations should be nearly identical. The challenge will be picking appropriate coefficients. You'll have to research how Sherman develops his flow coefficients for RESFEN if you want to compare the two analysis methods directly and he is the best source I know for small house infiltration data. There are numerous details to consider. Old windows probably are presumed to be leakier than new windows. There may also be factors for building height that generates stack pressure in addition to wind forces and/or other factors he has developed from his testing and measurement.
Ned Lyon
Senior Project Manager
Simpson Gumpertz & Heger Inc.
41 Seyon Street
Building #1, Suite 500
Waltham, MA 02453
Phone: 781-907-9000
Fax: 781-907-9009
>>> rbrahme@xxxxxxxx 7/2/2004 4:56:13 PM >>>
This may or may not have anything to do with EnergyPlus. I am simulating a typical residence (Brownsville, TX, weather file) using EnergyPlus. The assumptions are similar to the assumptions for RESFEN 3.1. The heating load is similar to that of RESFEN, but the cooling is about 1/3rd. I have been trying to figure what it is that I am missing for past couple of days, but with no luck. The current file has a HVAC system, but even with purchased air, the ratios are same. One thing that I am not simulating is the natural ventilation (which RESFEN simulates. It uses Enthalpic * Sherman-Grimsrud method). So, if any one can tell me what would be a simplified equivalent to the natural ventilation used in RESFEN that will be great.
I have uploaded the file. It is called 1-sto-nogar-sch.idf
Thanks
Rohini
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