[Equest-users] [Bldg-sim] Process Equipment Power Consumption

[Nick Caton]

Carol et al,

 

Here's my current understanding of the options we have (specifically in
eQuest) to specify equipment loads (from my head - correct me if I'm
off):

-          You may enter one (optionally, up to 5) distinct W/SF or kW
value for a zone to represent the full equipment load(s).  You may
optionally apply a diversity to the full load at this step here, but if
doing so you should modify your operation schedules as follows...

-          Each equipment load specified must be assigned a fractional
schedule.  You may choose to use 0's and 1's to model ON/OFF behavior,
but eQuest left to its own devices generates hourly schedules which
apply such diversity here.

-          The hourly thermal effects of each specified equipment load
may be reduced further by means of specifying the sensible and latent
load factors - values from 0 to 1.  By default, I believe equipment
loads generated by the wizards will have whatever you may have specified
for sensible (1.0 by default) and 0.0 for the latent portion.  The sum
of these two factors cannot exceed 1.0, and these factors have no effect
on the amount of energy consumed - only the heat contributions.

 

 

In the referenced and on-going (?) thread (discussing the intent and
means of handling/satisfying the LEED 25% default process load rule) I
brought up the possibility of specifying additional equipment loads with
a sensible/latent fraction of 0.0 - effectively consuming additional
energy to reach the 25% mandate, but also contributing nothing to
internal heat gains.  It was suggested, and I'm currently in agreement,
that an easier and less seemingly subversive approach to meeting the 25%
rule and achieving the same intentions would be to instead specify a
direct internal load to the electric meter.  It should be noted some
feel strongly that the 25% rule itself ought to be ignored entirely, but
if this topic interests you I'd suggest replying to that discussion
thread for clarity's sake ;).

 

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Carol
Gardner
Sent: Wednesday, May 05, 2010 1:04 PM
To: Yuvaraj Saravanan
Cc: eQUEST Users List; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] [Equest-users] Process Equipment Power
Consumption

 

I do not believe we are double discounting. Try this: think of when you
turn your computer on and off however you do so during the day, lets say
on at 9 am off at noon on at 1 pm off at 5 pm. That is your schedule.
Now think of how when you walk away from your computer for any length of
time and it goes into sleep mode, that's your diversity. 

Comments, thoughts are welcome. Is this what you were maybe getting at
with the multiplier, Nick.

Waiting to learn more,
Carol

On Wed, May 5, 2010 at 10:02 AM, Yuvaraj Saravanan <
Yuvaraj.Saravanan at arup.com> wrote:

Hi Carol,

This question is not specific to equest. Would you apply a diversity as
well as a schedule for process load? I thought by applying a schedule we
are accounting for diversity. By applying a diversity and then a
schedule are we not double discounting the load?

Regards,

Yuvaraj

 

From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Carol Gardner
Sent: Tuesday, May 04, 2010 11:15 PM
To: Gaurav Mehta
Cc: equest-users at lists.onebuilding.org


Subject: Re: [Equest-users] Process Equipment Power Consumption

 

Whenever you have an equipment, aka process, load it is proper to apply
first a diversity factor, aka % on at one time, and then a schedule.
Whether your building is new or existing doesn't matter. This is an Art
not a Science. Experience is the primary teacher. You can always ask us
old farts. We are relevant and have information that one only can get
with time. Yours to chose to listen to or not.

Peace out,
Carol

On Mon, May 3, 2010 at 9:20 PM, Gaurav Mehta <gmehta75 at gmail.com> wrote:

Please refer to the Chapter 18, Nonresidential Cooling and Heating Load
Calculations of the 2009 ASHRAE Handbook of Fundamentals.


Best regards,

Gaurav Mehta

Stantec


--------------------------------------------------
From: "Walson, Kristy" <kristy.walson at tlc-eng.com>
Sent: Monday, May 03, 2010 11:29
To: <omoltay at mimtarch.com>; <equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Process Equipment Power Consumption

	 

	Hi Omer,
	
	On recent projects, I have had to pay more attention to the
process loads for the types of equipment you mentioned below.  In the
past, I would just ensure that my process energy cost was 25% of the
total energy cost because I knew that the types of buildings I was
modeling (commercial offices, mostly) would never have an actual process
load even close to 25%.
	
	However, recently I have been modeling process loads in a more
exact way. What I do is I take the kW rating of the equipment, then I
talk to the electrical engineer to get an idea of whether that equipment
will ever run at its rated load and, if not, I apply the appropriate
reduction to it based on what the electrical engineer says.
	
	Once I have this maximum energy use for process loads in the
building, I then create a custom schedule for this process energy.
Sometimes I need to create more than one custom schedule based on the
type of equipment in the space.  This can become very tedious if you get
too far into the weeds, so I try to keep the schedules realistic, but
simple and I keep the number of different custom schedules I create to a
minimum.  As we all know, you can never know the actual occupancy and
use schedule of a building until it is occupied for a certain period of
time, so keep your assumptions simple and logical.
	
	I'd love to hear what other folks are doing if it differs from
my process.
	
	Kristy Walson, PE, LEED AP
	Mechanical Engineer / Sustainable Design
	
	-----Original Message-----
	From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of 
omoltay at mimtarch.com
	Sent: Monday, May 03, 2010 1:46 PM
	To: equest-users at lists.onebuilding.org
	Subject: [Equest-users] Process Equipment Power Consumption
	
	Dear All,
	
	One of the things that cause most trouble for us in modelling is
the power
	consumption of equipment such as dishwashers, ovens, food
warm-up
	equipment and so on that have varying levels of power
consumption during
	operation (even PCs and laptops). We are sometimes using
nameplate
	installed kW values, but deep inside we know that this is quite
wrong -
	but we have no other more reliable source / guideline for such
equipment.
	I would appreciate any feedbacks on how others are modelling
such
	equipment.
	
	Thank you,
	
	Omer Moltay, LEED AP
	Mimta
	
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