[Bldg-sim] Subject: How do you model minimum and high efficiency DX

Samuelson, Holly hsamuelson at gsd.harvard.edu
Mon Apr 14 14:09:47 PDT 2025 

Hi Jason,
For #2, yes, we end up with different estimated heat pump COPs at different operating conditions.  This paper shows what that might look like.
Optimizing window solar heat gain coefficient for energy and carbon performance in a changing context of electrification and decarbonization - ScienceDirect<https://www.sciencedirect.com/science/article/pii/S2352484725000125#fig0030>
Best,
Holly

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Today's Topics:

   1. Re: Bldg-sim Digest, Vol 209, Issue 2 (Jason Glazer)


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Message: 1
Date: Mon, 14 Apr 2025 06:28:39 -0500
From: Jason Glazer <jglazer at gard.com>
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Bldg-sim Digest, Vol 209, Issue 2
Message-ID: <2eed702c-fc4d-4475-aa3f-0cc45d5e32e7 at gard.com>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

Holly


Thanks for providing the background on such an interesting
approach. Do you end up with a map of COPs at different
operating conditions in your spreadsheets, especially for 2?
Is that something you could share?


Jason


On 4/11/2025 4:27 PM, Samuelson, Holly via Bldg-sim wrote:
> Hi Jason,
> Regarding modeling the efficiency of equipment...
> It depends on whether you're modeling a specific system
> for a specific building project, or if you're trying to
> model generalized performance, for example for research.
> I'll comment on the latter scenario.? For generalized
> research purposes, where we don't know the exact heat pump
> system and configuration, my team has found that energy
> simulation results are too sensitive to many of the heat
> pump details in the energy model.? Therefore, to avoid our
> results being overly-specific to one heat pump model and
> configuration we've done one of the following two things.
>
> 1.
>     We've output the annual heating and cooling demands
>     from tour energy model, then applied the heat pump
>     heating or cooling COPs ?in a spreadsheet.? We've
>     found the COPs from a published study with realized,
>     weather-dependent, COPs (from representative climates
>     and buildings)
>
> 2.
>     We've also done this with hourly performance, based on
>     realized, weather-dependent COPs at different
>     temperatures from representative field studies. For
>     interpolation, we've calculated the maximum possible
>     COP (based on the Carnot Cycle) for each time step,
>     then scaled those values down to something more
>     realistic, based on the results from the published
>     field studies.
>
> Hope this helps.
> Best,
> Holly
>
>
> A black and white letter h Description automatically generated
>
>
>
> *Holly Samuelson*
>
> Associate Professor of Architecture
>
> Harvard University | Graduate?School of?Design
>
> www.hollysamuelson.com<http://www.hollysamuelson.com> <http://www.hollysamuelson.com/>
>
> /Unless otherwise noted, I do not expect a reply outside
> your normal working hours. /
>
>
>
> ------------------------------------------------------------
> *From:*?Bldg-sim <bldg-sim-bounces at lists.onebuilding.org>
> on behalf of bldg-sim-request at lists.onebuilding.org
> <bldg-sim-request at lists.onebuilding.org>
> *Sent:*?Thursday, April 10, 2025 4:00 PM
> *To:* bldg-sim at lists.onebuilding.org
> <bldg-sim at lists.onebuilding.org>
> *Subject:*?Bldg-sim Digest, Vol 209, Issue 2
> Send Bldg-sim mailing list submissions to
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> Today's Topics:
>
> ?? 1. How do you model minimum and high efficiency DX
> cooling and
> ????? heat pump equipment? (Jason Glazer)
> ?? 2. Re: How do you model minimum and high efficiency DX
> cooling
> ????? and heat pump equipment? (chris.malcolm.yates at gmail.com)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 10 Apr 2025 08:28:44 -0500
> From: Jason Glazer <jglazer at gard.com>
> To: bldg-sim at onebuilding.org
> Subject: [Bldg-sim] How do you model minimum and high
> efficiency DX
> ??????? cooling and heat pump equipment?
> Message-ID: <bf88e843-c541-47e9-9462-0ff92a23c74a at gard.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> I just posted a question on unmet hours:
>
> https://unmethours.com/question/101487/how-do-you-model-minimum-and-high-efficiency-dx-cooling-and-heat-pump-equipment/
> <https://unmethours.com/question/101487/how-do-you-model-minimum-and-high-efficiency-dx-cooling-and-heat-pump-equipment/>
>
> "I?m trying to get an understanding of the practice of
> modelers when comparing minimum efficiency and
> high-efficiency DX equipment and heat pumps for different
> applications. I know that detailed performance data is
> sometimes difficult to get. How successful have you been in
> trying to get detailed performance data from vendors? If you
> can?t get data like that, how do you model the equipment?
> How do you model the indoor fan? If you know it is
> multispeed, how do you figure out those details? What if all
> you have is the AHRI data (EER/EER2, SEER2/IEER, COP at
> 17/47, capacities, full load/intermediate/minimum airflows)
> what assumptions do you have to make? What performance
> curves do you use? If you can get data from the
> manufacturer, what assumptions do you still need to make? Is
> it different for residential size equipment than commercial?"
>
> If you can respond to this email or post a response on
> unmethours, I would appreciate it.
>
> Thanks
>
> Jsaon
>
>
> --
> Jason Glazer, P.E., BEMP, GARD Analytics, ASHRAE 209 chair
> Admin for onebuilding.org building performance mailing lists
>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 10 Apr 2025 15:47:12 +0100
> From: <chris.malcolm.yates at gmail.com>
> To: "'Jason Glazer'" <jglazer at gard.com>,
> <bldg-sim at onebuilding.org>
> Subject: Re: [Bldg-sim] How do you model minimum and high
> efficiency
> ??????? DX cooling and heat pump equipment?
> Message-ID: <000801dbaa27$72659cf0$5730d6d0$@gmail.com>
> Content-Type: text/plain;?????? charset="UTF-8"
>
> Hi Jason,
>
> I asked this question over a decade ago to a couple of
> different suppliers in the UK. What intrigued me was the
> very high efficiency that suppliers (e.g., Mitsubishi,
> Daikin) quoted - figures that we just plugged into
> building code calculations. Based on these figures it
> seemed like a no-brainer to just rip out centrifugal
> chillers and replace them with acres of DX systems! My
> enquiries came to little. The only interesting thing that
> I got (from a Danish academic) was that the market was
> very Germany-centric which resulted in SEER & COP being
> established at what seemed like, for the UK at least,
> quite extreme temperature bins.
>
> The impression I got is that, locally, there is some
> design experience within the sales teams but it's limited
> to sizing. The best I got back in terms of energy was
> something along the lines of "we've got some boffins over
> in Japan, we can try asking them."
>
> I don't doubt that they have some very clever people. Are
> they clever enough to get centrifugal-like performance out
> of a scroll compressor? I don't know. Reading your
> message, it's interesting to see that maybe the US market
> is subject to the same "black box" issues!
>
> Good luck. I'll keep an eye on this thread and Unmet hours.
>
> Cheers
>
> Chris
>
> -----Original Message-----
> From: Bldg-sim <bldg-sim-bounces at lists.onebuilding.org> On
> Behalf Of Jason Glazer via Bldg-sim
> Sent: 10 April 2025 14:29
> To: bldg-sim at onebuilding.org
> Subject: [Bldg-sim] How do you model minimum and high
> efficiency DX cooling and heat pump equipment?
>
> I just posted a question on unmet hours:
>
> https://unmethours.com/question/101487/how-do-you-model-minimum-and-high-efficiency-dx-cooling-and-heat-pump-equipment/
> <https://unmethours.com/question/101487/how-do-you-model-minimum-and-high-efficiency-dx-cooling-and-heat-pump-equipment/>
>
> "I?m trying to get an understanding of the practice of
> modelers when comparing minimum efficiency and
> high-efficiency DX equipment and heat pumps for different
> applications. I know that detailed performance data is
> sometimes difficult to get. How successful have you been
> in trying to get detailed performance data from vendors?
> If you can?t get data like that, how do you model the
> equipment?
> How do you model the indoor fan? If you know it is
> multispeed, how do you figure out those details? What if
> all you have is the AHRI data (EER/EER2, SEER2/IEER, COP
> at 17/47, capacities, full load/intermediate/minimum
> airflows) what assumptions do you have to make? What
> performance curves do you use? If you can get data from
> the manufacturer, what assumptions do you still need to
> make? Is it different for residential size equipment than
> commercial?"
>
> If you can respond to this email or post a response on
> unmethours, I would appreciate it.
>
> Thanks
>
> Jsaon
>
>
> --
> Jason Glazer, P.E., BEMP, GARD Analytics, ASHRAE 209 chair
> Admin for onebuilding.org building performance mailing lists
>
> _______________________________________________
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--
Jason Glazer, P.E., BEMP, GARD Analytics, ASHRAE 209 chair
Admin for onebuilding.org building performance mailing lists
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