Student Request: Unrealistic EUI

asked 2017-01-08 16:04:40 -0500

mbcoalson gravatar image

updated 2017-01-09 05:17:25 -0500

I'm modeling a building in Openstudio. Not being a professional there is a tremendous amount I don't understand about the practical aspects of equipment selection. All of the zoning I've done is extremely simplified. My main goal is to get an intuitive feel for the advantages and disadvantages for the most common HVAC systems and to improve my modeling skillset. Which is all preamble for, please forgive my ignorance.

What I've done so far: Using NREL's tutorial videos and a month subscription to Energy-modeling I have created a successfully running model.

I've modeled three basic setups:

  1. Ideal Airloads (EUI ~ 56 kbtu/ft^2)
  2. Packaged Rooftop VAV System with Reheat (EUI ~ 111 kbtu/ft^2)
  3. Packaged Rooftop Heat Pump. (EUI ~ 813 kbtu/ft^2)

The packaged rooftop heat pump unit is coming back with extremely different results in both Openstudio and Energyplus results. Worse is that there isn't even a heating load on the rooftop system and given the climate (ASHRAE 6A) that is completely unrealistic.

I'd like to hear suggestions or, ideally, start a dialogue about system sizing and selection process.

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With the amount of information you're providing, we can't really do much... Clearly it's unrealistic, but it could have come from a variety of things. Check if you're hitting the setpoints you define, and that you don't have simultaneous heating and cooling, etc.

Julien Marrec gravatar image Julien Marrec  ( 2017-01-09 05:19:00 -0500 )edit