[Bldg-sim] How do you model minimum and high efficiency DX cooling and heat pump equipment?

[chris.malcolm.yates at gmail.com]

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/

"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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