HVAC Templates and Adjusting COP

Hey all, happy Thursday!

I’m doing some research on heat resilience and I’ve run into a couple of questions. The first is on matching the best HVAC template to an existing system, and the second question is in the adjustment of the templates COP.

Some notes: I am using LB tools 1.2.0 in Rhino 7. We are only looking at a week-long heatwave so heating is not important and, we are sizing by the 99.4% and .4% design days.

In some documentation that has been provided to us, we have been provided a collection of the most common units used in the area we are working in: Rooftop Packaged Units, and Ducted Split Units.

In order to most accurately model the Ducted Split System, it is my assumption that we should use the VRF template, at the moment we are accounting for ventilation through infiltration. We would like to also test a heat recovery system, in which case is it my assumption that we should use the DOAS with VRF template. Are these assumptions correct? If not…any suggestions?

In the case of modeling the rooftop packaged system. It was my initial reaction to use the PTAC template, but realized that this template was approximating something more like a hotel AC - not what we want. Weirdly, when I investigated this template further in OpenStudio, there was nothing in HVAC to be seen. I have since come to the conclusion that the PSZ template is going to most closely approximate a packaged rooftop unit, any thoughts on this conclusion?

Now, part of this issue is that the research involves adjusting the system’s COP. For this, I realize that it would make sense to write my own OS measure, though this goes a bit beyond my abilities. Instead, I was using this NREL measure written by kflemin. Interestingly, this measure does not work for several templates that I tested, namely the PTAC, PSZ, Residential AC and VRF templates but does work with the DOAS - VRF and PVAV-PFP templates. The PTAC template returns: 1. Solution exception:undefined method `coolingCoil’ for #OpenStudio::Model::CoilHeatingElectric:0x000001a5a3bfd5e8 and the others simply make not COP adjustments. Thoughts on why this might be the case would be greatly, greatly appreciated.

So, in summary, I am presented with a couple of issues, primarily, which honeybee template is going to best approximate the HVAC systems of interest, and secondly, what is the best way to adjust these system’s COPs within Honeybee, short of dedicating all my time to learning how to write an OS measure :smiley:

I would like the adjustment to be made through honeybee because we are looking at a number of variables and are building up the simulation environment in the GH world.

Any advice is greatly appreciated!!!
Thank you for your amazing work LB Team <3.

Both your selections of HVAC templates make sense. PTACs aren’t usually installed on roofs and every room typically has its own PTAC hanging off the exterior wall.

Writing an OpenStudio measure is definitely one way to do your research but I know Ruby and the OpenStudiop SDK have a learning curve. If you have more knowledge of Grasshopper than you do Ruby, you can alternatively build a custom HVAC system component-by-component using IronBug and you can apply the HVAC system you create to your OpenStudio model like so:

Fantastic, thanks for the link. I’ll investigate Ironbug. Thank you for your time!