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Details on OpenStudio AEDG K12 GSHP DOAS measure

asked 2014-10-23 18:10:42 -0600

keb gravatar image

updated 2015-11-12 16:09:16 -0600

Please provide further details regarding this measure. What are its limitations? Its main assumptions? This measure nicely strips existing HVAC equipment from a model and runs an "optimally-sized" ground loop and that it "reflects the HVACE recommendations of the 50% K-12 AEDG" guide. How is this ground loop size calculated to float between 5C and 21C as the measures specifies, and what/where are the soil properties and borefield configuration details that influence the performance of the ground exchanger?

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@Kent Beason "geothermal" and/or "geo-exchange" and/or "ground-coupled heat exchanger" might be good tags as well, especially if your end goal is modeling a geo-exchange system more so than specifically using the AEDG model.

DancingDavidE gravatar image DancingDavidE  ( 2014-10-23 18:30:56 -0600 )edit

Thanks for adding those tags.

keb gravatar image keb  ( 2014-10-23 18:41:31 -0600 )edit

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answered 2014-10-24 01:07:34 -0600

updated 2014-10-24 01:08:50 -0600

Kent, the ground source heat pump was one of the tricker HVAC AEDG measures to develop. We do not attempt to size the field loop. We use a scheduled setpoint manager by district cooling and district heating objects to control the float. The idea here is to give a good sense of what the potential benefit of a ground source heat pump is. As the design develops information will be needed about soil properties and the loop configuration. For reference attached is a screenshot of the heat pump plant loop. Also as noted in the measure modeler description, the energy use associated with the district heating and cooling isn't currently removed from the simulation results.

image description

Since the AEDG measures have been published we have also published a series of measures and a tutorial showing how to use GLHEPro in conjunction with OpenStudio. Here are links to the measures and tutorial.

GLHEPro measure search in BCL

GLHEPro OpenStudio tutorial

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Great! Thanks. "Achieving a good sense" is my main objective currently, not down to design-specifics yet. I believe the district heating/cooling energy usages are simply a place holder/dummy for the ground exchanger? For instance, in PAT, the results of this measure would need to be post-processed to exclude the district heating/cooling?

keb gravatar image keb  ( 2014-10-24 08:08:48 -0600 )edit

@Kent Beason yes, you are correct, the district heating and cooling objects are placeholders to represent a ground exchanger with enough capacity to keep the water temperature within the desired bounds, and that you would need to remove this energy from the model before computing EUI, etc. as this energy wouldn't actually be used if an actual ground heat exchanger were used. The reason we didn't use an actual ground HX is that EnergyPlus can't currently autosize them, so if you ran the measure on a random building, we couldn't guarantee that the system would work.

aparker gravatar image aparker  ( 2014-10-24 09:50:36 -0600 )edit

@aparker, If I wanted to run a Distributed Analysis with this measure implemented as the hvac system as a placeholder itself (since ultimately the hvac system will be a geo), would the district heating and cooling object be problematic by the "extra" energy associated with them? Just curious. The total heating and cooling energies would be inflated. Or would DA simply be better suited for something like ideal loads...

keb gravatar image keb  ( 2014-12-08 13:16:20 -0600 )edit

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Asked: 2014-10-23 18:10:42 -0600

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Last updated: Oct 24 '14