[Bldg-sim] Estimating Energy Consumption Using Spreadsheets

[Michael Andelman]

The 'hilarious' thing is that EnergyPlus was introduced with much fanfare in
2001.  At the time it was described as a program designed to be used with an
interface (though I noticed that now they it's a "stand alone program
without a 'user friendly' graphical intrerface").  
Nine years later we're still waiting for a fully functional interface!



Mike

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Griffith, Brent
Sent: Wednesday, February 24, 2010 9:48 AM
To: Eric Studer; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets



I'd guess that, back when DOE2 took an hour to run, this sort of reasoning
was often used to justify hanging on to spreadsheets.  

Your understanding of the Fortran in E+ is incorrect.  E+ is getting faster
with each release.  

> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-
> bounces at lists.onebuilding.org] On Behalf Of Eric Studer
> Sent: Wednesday, February 24, 2010 4:32 AM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets
> 
> Hello Brent,
> 
> I agree that DOE2 does not perform the same degree of calculations as E+
> or
> other newer calculation engines, but it does allow us to get a reasonably
> accurate estimate of savings for a wide range of design options without
> having to wait hours for results.  In addition, we can access intermediate
> results to diagnose modeling problems or check to see if we are modeling
> unique systems correctly.  We will switch to E+ when it can run as fast as
> eQuest and/or when there is a user interface that allows us to model a
> wide
> array of HVAC systems and easily check intermediate results.
> 
> I am curious, do you or anyone else over at NREL have comparisons of
> projected savings generated using DOE2 and E+ for the same base and
> proposed
> case envelope designs calibrated to actual energy use of a real building?
> We may switch from eQuest if there is evidence that there is a substantial
> difference in the accuracy of energy savings estimates.
> 
> It is my understanding that the E+ FORTRAN code is an agglomeration of DOE
> programming from the past 30 years that may not be operating as smoothly
> as
> it could be.  Do you know if there are any efforts underway to speed up
> the
> processing time?
> 
> Eric
> 
> Ph:   (781) 431-1100 ext 12
> Fax:  (781) 431-1109
> 
> -----Original Message-----
> From: Griffith, Brent [mailto:Brent.Griffith at nrel.gov]
> Sent: Monday, February 22, 2010 10:40 PM
> To: estuder
> Subject: RE: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets
> 
> 
> Oh this is hilarious, "do things right in eQuest."   sounds impossible,
> eQuest may be better than spreadsheets of yore,  but it is hardly state of
> the art.  how can you evaluate a building envelope upgrade without decent
> thermal comfort results?
> 
> ________________________________________
> From: bldg-sim-bounces at lists.onebuilding.org
> [bldg-sim-bounces at lists.onebuilding.org] On Behalf Of estuder
> [estuder at dmiinc.com]
> Sent: Monday, February 22, 2010 4:54 PM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets
> 
> Hello!
> 
> There is a good reason people don't use spreadsheet analyses very much
> anymore for building modeling.  I used bin models for many years to
> estimate
> HVAC energy use and kept improving my technique until I arrived at what
> was
> dubbed the Osama bin Model approach.  In the end, I ditched this to learn
> how to do things right in eQuest.
> 
> What was the big lesson?  Bin models at best are big sloppy averaging
> exercises that use first principals (read: "easy math") to determine
> operation at any one point in time.  This is cool for ventilation
> calculations where the loads are instantaneous and related directly to
> ambient conditions, but definitely not a good way to model the impacts of
> anything that has time lags/delayed responses.  How do you estimate the
> benefit of commercial building envelope upgrades?  Most savings arise
> during
> unoccupied periods, primarily from reduced cycling of fans, pumps, cooling
> systems, and boilers.  Sure there are reduced heating/cooling loads, but
> how
> do you estimate the heat loss when you can't estimate what the average
> interior temperature is going to be?
> 
> Yeah, spreadsheet calcs definitely have their place and I still do use
> them.
> I have found that eQuest is a whole lot faster and more accurate than the
> ol' Osama bin Model when doing whole-building analyses.
> 
> Eric
> 
> __________________
> 
> Eric Studer, PE
> Project Manager
> DMI
> 35 Walnut Street
> Wellesley, MA
> (781) 431-1100 ext 12
> Fax: (781) 431-1109
> 
> 
> 
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Daniel
> Croisant
> Sent: Monday, February 22, 2010 4:50 PM
> To: bldg-sim at lists.onebuilding.org
> Subject: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets
> 
> Hello,
> 
> I've "grown-up" in the time when energy modeling programs always existed.
> I'm curious if anyone that has been in the business for awhile has any
> experience using spreadsheets to estimate a building's energy consumption,
> and if so, would you be so kind as to share them with me?  I'm not looking
> to use it on any projects and would not try to hold anyone liable for any
> results.  I'm just curious as to how people tackled the issue of
> estimating
> energy usage, other than degree days, before the popularization of DOE and
> other energy modeling programs.  Plus I think it would just be fun to play
> around with what other people have used.
> 
> Thank you in advance,
> Dan Croisant
> Mechanical Design Engineer | LEED AP
> Direct  262.522.4414
> 
> I B C ENGINEERING SERVICES, INC.
> N8 W22195 Johnson Drive, Suite 180
> Waukesha, Wisconsin  53186
> T 262.549.1190  : :  F  262.549.1620
> 
> www.ibcengineering.com<blocked::http://www.ibcengineering.com>
> 
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