[Bldg-sim] ASHRAE Appendix G EER Calculation

[Sam Mason]

Karen,
>From the user's guide, the fan power should be removed from the standard EER rating of packaged cooling systems. Excerpt below but let me know if you have any further questions.

A 15-ton packaged rooftop single-zone system having an EER of 8.6 (COP of 2.5) is
specified for a building. The following table gives the design specifications. How should
this be modeled?
Equipment parameter                               Value
Net Cooling Capacity (Btu/h)                   174,000
Total Packaged Unit Input Power (W)        20,128
EER                                                         8.64
Gross Cooling Cap (ARI conditions)         182,000
A
The supply fan power is the difference between the gross and the net cooling capacity.
Supply Fan Power  = (182,000 - 174,000 Btu / h) / 3.413 Btu /W h =  2343 W

>From the equation for cooling system COP, the cooling provided by the compressor and
the condenser into the airstream in Btu/h per Btu/h of electrical power input is:
COP  = (182,000 Btu / h) / {(20,128 - 2343 W)* 3.413 Btu / W h } = 3.0
Some simulation programs use an energy input ratio (EIR), which is 1/COP. In this case,
the EIR for this piece of equipment would be 1/3 or 0.333.

--
Sam Mason
Atelier Ten

T  +1 212 254 4500 x221

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen Walkerman
Sent: Monday, January 31, 2011 3:53 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE Appendix G EER Calculation

A clarification:

My question pertains to baseline models, with baseline systems.

--
Karen

On Mon, Jan 31, 2011 at 12:09 PM, Karen Walkerman <kwalkerman at gmail.com<mailto:kwalkerman at gmail.com>> wrote:
Hi All,

G3.1.2.1 in ASHRAE 90.1 says that "Where efficiency ratings, such as EER and COP, include fan energy, the descriptor shall be broken down into its components so that supply fan energy can be modeled separately."

However, I am a little unclear as to which baseline systems this applies to.  It seems that it would apply to systems 1 - 2, and not to systems 3 - 8?

Thanks,

--
Karen

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