[Equest-users] Throttling Range and Pipe Insulation

[Daniel Bersohn]

All,

 

Use care with zone simplification.  The recommendation I made to use one zone per floor was because the system described usually doesn't have much effective zone by zone control in real life (especially true with one pipe steam), and in most instances looks something like one zone per floor.  The solutions to the unmet load hours problem in these kinds of cases are to: 

 

1)       model one zone per physical room or thermal block and use your real life control zone and just live with the unmet load hours, but be careful as the model may do things that are unrealistic on the energy side in this case

2)       model one zone per control in real life (i.e. if you have 3 thermostats, then model three zones) this may be more accurate in terms of energy for some cases, but may underestimate the real life unmet load hours of a poorly conditioned room within your real world system

 

If you have unmet load hours in, for example, a dormitory with a fan coil in each room, something's probably wrong with a schedule, an equipment capacity, or improperly defined system topology (system per zone, shell, site).  Improper use of zone simplification techniques is bound to screw up your energy story.  You'll end up getting results that don't make sense and you'll give your clients bad advice.

 

-Daniel

 

www.burohappold.com <http://www.burohappold.com/> 

 

________________________________

From: Shen, Jie CAR [mailto:jshen at emsi-green.com.cn] 
Sent: Thursday, January 28, 2010 8:50 PM
To: Daniel Vilavedra; Walt Henry; equest-users at lists.onebuilding.org; Susan Trzos
Subject: Re: [Equest-users] Throttling Range and Pipe Insulation

 

Hello, Walt: 

 

Do you think it can be changed in the Detailed Model? I checked about the Detailed model, it seems there's no functions to change footprint from one zone per floor  to perimeter/core. .

Since you know, if we change the Detailed Model into Wizard Model,  all the settings in the Detailed Model will be disappeared. That will be a great work load, I try that and found the only way is to copy all the settings from the old .inp document. 

 

Eleanor Shen 

Energy Specialist

LEED AP

EMSI

86.21.54962727-805 TEL

86.21.64435767 FAX

jshen at emsi-green.com.cn

www.emsi-green.com

 

 

 

 

 

 

 

 

 

________________________________

From: Daniel Vilavedra [mailto:Daniel.Vilavedra at pgigrup.com] 
Sent: Thursday, January 28, 2010 3:40 PM
To: Walt Henry; equest-users at lists.onebuilding.org; Susan Trzos
Subject: Re: [Equest-users] Throttling Range and Pipe Insulation

Thanks a lot

 

Daniel

 

________________________________

De: Walt Henry [mailto:WHenry at thielsch.com] 
Enviado el: miércoles, 27 de enero de 2010 21:05
Para: Daniel Vilavedra; equest-users at lists.onebuilding.org
CC: JMcCarthy at thielsch.com; Jean-Paul Vandeputte; Marion McCarthy - Rise Engineering; NPrice at thielsch.com; Noel Chambers; Stephen Szewczyk
Asunto: RE: [Equest-users] Throttling Range and Pipe Insulation

Hello Daniel, 

 

In either Wizard the footprint screen has the choice for zones to be one per floor or perimeter/core.  See attached screens.

 

Walt

 

________________________________

From: Daniel Vilavedra [mailto:Daniel.Vilavedra at pgigrup.com] 
Sent: Wednesday, January 27, 2010 9:18 AM
To: Walt Henry; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Throttling Range and Pipe Insulation

 

Hello walt,

 

Could you tell how did you change the footprint to one zone per floor or send me a picture showing it? My model is also outside of the throttling range and I'm trying to change it. I don't find where the option is.

 

Thanks a lot

 

 

 

________________________________

De: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] En nombre de Walt Henry
Enviado el: martes, 26 de enero de 2010 22:19
Para: Daniel Bersohn; equest-users at lists.onebuilding.org
Asunto: Re: [Equest-users] Throttling Range and Pipe Insulation

Hello Daniel,

 

Thanks for your responses to my requests.

 

1)       I did find the zone that was under heated in the reports.  This building has three zones and the basement was the under heated zone.  I changed the footprint to one zone per floor in lieu of perimeter/core and dropped the percentage from 34.1 to 0.9 so I am content with that since this is an existing system the we can't change.  

 

2)  I found the location of the losses tab in the water loop and see how the UA can be changed so that should solve the pipe insulation savings dilemma.  I can't fully agree with you regarding the need to insulate steam piping.  Although the pipe does heat the zone it is in the process of condensation in the piping degrades the quality of the steam reaching the distributors, radiators in this case.  This is a church and the piping to be insulated is basically 400' of 4", 120' of 2" and 100' of 1".  The function of the piping is to deliver good quality steam to the radiators and without insulation on long runs, even if they are in a heated zone takes away steam quality from the zone above and the radiators in the zone where the pipe is located.

 

Thanks again!

 

Walt

________________________________

From: Daniel Bersohn [mailto:Daniel.Bersohn at BuroHappold.com] 
Sent: Thursday, January 21, 2010 6:09 PM
To: Walt Henry; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Throttling Range and Pipe Insulation

 

Walt,

 

1)       This means that you have a zone that's not getting heating or cooling when it wants it.  34.1% probably means there's an issue with your system topology or your system really has unmet load hours in real life.  If you have one thermostat and lots of rooms with different internal loads and exposures you're guaranteed to get a lot of unmet load hours.  The plant having zero unmet load hours means the plant is satisfying all the requests its getting from equipment that serves zones.  So the zones aren't getting what they want from AHUs, radiators, etc. but the plant is doing everything AHUs, radiators etc. want it to.

2)       Any piping downstream of a steam control valve in a two-pipe system in the same space served by the radiator doesn't need insulation because it's acting as a radiator.  In a one-pipe system,0 if you have TRVs on the air vents, any pipe that only serves one radiator and is in the same space as that radiator need not be insulated since it serves as a radiator.  If you don't have TRVs on your air vents in a one pipe system (or in place of the control valves on two-pipe for that matter) the insulation probably doesn't matter that much since all the radiators deliver heat (and too much of it at that) at the same time as all the uninsulated pipe.  For the remaining pipe you'd estimate the surface area of the piping to be insulated and multiply the U factor of the insulation by the surface area of the pipe.  Put that into the hot water loop you're using as an analog for your steam system in detailed mode.    

 

Daniel Bersohn, LEED AP
Mechanical Engineer
Buro Happold Consulting Engineers PC
100 Broadway
New York, NY 10005 USA

+1 212 334 2025 Office
+1 212 616 0391 Desk

daniel.bersohn at burohappold.com
www.burohappold.com <http://www.burohappold.com/> 

________________________________

From: Walt Henry [mailto:WHenry at thielsch.com] 
Sent: Thursday, January 21, 2010 8:55 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Throttling Range and Pipe Insulation

 

Good morning eQUEST users,

 

I have two requests:

 

1)       What is the definition of "throttling range"?  I have always had 0 until my last project which is a Police Station.  We do mostly energy retrofits and the existing boiler, 37 years old, has an input of 450 MBH.  The total HVAC load is 222.651 MBH per eQUEST.  For the first time Report BEPU shows my base case model to be 34.1% outside of the throttling range.  What does this mean?  The % of hours any plant load is not satisfied is 0.

 

2)       I have a church to model, starting this morning, which has no insulation on the steam piping and we want to determine the savings by putting 1" of              fiberglass on the pipes.  Usually we would determine the savings in e-plus but is there any way to model this in eQUEST?  There are other measures and it would be convenient to have everything in one report.

 

Walt Henry

Energy Specialist

RISE Engineering

1341 Elmwood Ave.

Cranston, RI 02910

U.S.A.

Phone:  401-784-3700 Ext. 119

Fax:      401-784-3710    

 

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