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2016-03-01 11:52:34 -0500 | commented answer | Large discrepancy between modelled HVAC and district heating/cooling My main concern is that EnergyPlus reports district cooling end use to be approximately 40 times larger than that of district heating, when IdealLoads is used instead of actual HVAC (which more expectedly reports heating end use to be approximately twice as much as cooling end use). The outdoor air is the same as in the original ASHRAE model. I do not see enough COPs around that would be able to explain this. Result table for modified model, if needed, is here: https://www.dropbox.com/s/6q23ibfck4a... |
2016-03-01 09:04:32 -0500 | received badge | ● Student (source) |
2016-03-01 09:02:38 -0500 | asked a question | Large discrepancy between modelled HVAC and district heating/cooling I am trying to optimise exterior shading design for an office building. To make a head start with building and climate, I have chosen large office building from the ASHRAE's 90.1-2013 Commercial Building Prototype Models, to be simulated with Chicago climate. Further, in order to speed up simulations as I'd like to employ genetic algorithm in optimisation, I have decided to delete all HVAC related details from the model and replace them with IdealLoadsAirSystem for each zone, such as: ZoneHVAC:IdealLoadsAirSystem, The problem now is that there is a large discrepancy between results obtained for heating and cooling loads. The initial ASHRAE model requires 10.8 GJ of electricity and 5325.81 GJ of natural gas for heating, and 2748.36 GJ of electricity for cooling. However, the IdealLoadsAirSystem version reports only 550.65 GJ for district heating and 21417.95 GJ for district cooling. Hence almost 10 times less energy for heating and almost 8 times more energy for cooling?! What am I doing wrong here? Convincing demystifications are welcome! What has to be done to keep IdealLoads (and shorter simulation times), yet to obtain more realistic ratio of heating/cooling loads? If you're interested, you can see the modified IdealLoads version of the model at https://www.dropbox.com/s/3xcsr4ighrg... Thanks in advance, Sanya Stevanovic |