Building Simulations

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Building Simulations

Work collaboratively to find easier, more accurate and better ways to model, predict and verify a home's energy consumption.

Members: 70
Latest Activity: Jan 28

I spent many years modeling energy use in buildings using DOE2 and have modeled millions of square feet of commercial buildings and am quite familiar with that program's limitations. I'll admit up front that I am not a fan of DOE2. I much prefer continuous models that are object oriented. I do not like models that are based on discrete hourly approximations, although I understand why we sometimes need them in the short term.
Since coming to work for an electric electric utility 12 years ago, I have been analyzing commercial and residential building energy consumption by plotting average Watts/Ft2 (or Watts/m2) verses average monthly temperature that I obtain from monthly utility billing data. The resulting graphs are much more useful than the single number that is produced by EnergySTAR's Portfolio manager. The graph readily illustrates energy conservation potential, indicates which system is using the most energy (heating, building envelope, cooling, reheat or baseload), and is able to verify and quantifty improvements in energy performance after only one month of improvements being made to a facility. I'm happy to share this approach with any other building scientists that are interested.
I have also been using Matlab and Simulink to create a dynamic models of residential building's heating and cooling system. The results are quite interesting. My current model includes the effects of temperature setback on interior building materials and air temperatures. I will also be adding electric heat pumps to see how their auxilliary electric heaters respond to agressive temperature setbacks and to variations in outside air temperatures. I am trying to add mass effect of exterior surfaces to mimic those systems as well.

Discussion Forum

Transient Heat Transfer Analysis 5 Replies

I have put…Continue

Tags: element, difference, finite, transfer, heat

Started by James White. Last reply by James White Dec 10, 2013.

Trying to find %age energy saving from variety of upgrades in 10K sf multifamily house 4 Replies

I'm trying to figure out %age of energy savings from a variety of upgrades in a 10,000 sf building that has had deferred maintenance and a disfunctional heating system.I'm using Energy Pro software…Continue

Started by George M. Matthews. Last reply by Guy DuBois Mar 18, 2013.

Using Average Monthly Temperature to Model Home Energy Use 16 Replies

Discuss how monthly electric and gas billing data can be combined with average monthly temperature data to model a building's energy use, quantify energy conservation opportunities and verify…Continue

Started by James White. Last reply by James White Dec 28, 2012.

How about simulation in the multifamily context? 6 Replies

We'd like to hear from you on how the topic of this group applies in the context of multifamily buildings---> here

Started by Evan Mills. Last reply by Don Hynek Jan 23, 2012.

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Comment by Srikanth Puttagunta on November 23, 2010 at 1:05pm
It is not a picture, it is a video tutorial of an Excel Spreadsheet that can be downloaded at www.carb-swa.com. You can also see the video posted on youtube. The video can be expanded to full screen by pushing the button in the lower right of the video. Might be best to download the actual dashboard and play around with it a bit. Thanks.
Comment by Steve Waclo on November 23, 2010 at 12:39pm
Hello Srikanth and welcome to HEP!

Very much want to provide input on the Dashboard Video Tutorial, but (at the risk of broadcasting my ignorance, which frankly, has never stopped me before) was unable to scale up the picture large enough to follow the narration. How can I format a full screen (or close) HD image?

BTW, how often do you get mail destined for California Air Resources Board ?

Steve
Comment by Srikanth Puttagunta on November 23, 2010 at 8:15am
I posted a video to the website called: Retrofitting America: a 1970s Home Energy Efficiency Analysis. The idea was to make a dashboard (which can be downloaded at www.carb-swa.com) with general information to guide initial decisions on packages of retrofits to pursue. The intended audience is utility programs and homeowners, focusing on utility bill savings. It doesn't replace actual energy modeling, but hopefully can steer people when making decisions. I would be very interested in the groups thoughts on a tool of this nature. The plan is to provide additional options (building orientation, window to wall ratio options, and two story option). Thanks.
Comment by James White on November 19, 2010 at 1:29pm
Hello David, (1) although Y axis is listed in kW (power), it is an average of the energy used in a month. A more accurate label would be kWh per hour, but I think that would be too confusing. If I were to be technically correct, I should also be referring to "mean monthly temperature" instead of "average monthly temperature". (2) I agree that the heating and cooling lines are best described as linear functions over their related temperature ranges, but Excel does not easily curve fit two separate linear lines to a prabolic series of data.
Comment by David Fay on November 19, 2010 at 12:44pm
James, thanks for sharing your average temperature spreadsheet. A couple of quick comments: (1) the y-axis is mislabeled (you are plotting power not energy); (2) I don't know what function you are fitting to the data but it looks like you should be using piecewise linear regression, with one line describing the heating season and the other, the cooling season.

David
Comment by James White on November 19, 2010 at 8:23am
Attached is the average temperature spreadsheet that shows the normailized energy use of my home. It contains the graph that I used as the icon for this forum.WhiteRes013108.XLS
Comment by David Fay on November 19, 2010 at 7:03am
"I'm happy to share this apporach with any other building scientists that are interested." Please do. Is there any place we can read about this approach?

David
Comment by Steve Waclo on November 18, 2010 at 6:40pm
Hello again James.

When I worked for PEPCO back in the 70's we had rather primative simulation software, but were able to increment DHW temperatures and watch the results. Are contemporary residential programs able to account for different dishwasher operating techniques (as J.C. and I discussed), or is that putting too fine a point on the subject? Scenario 1) Gas DHW @ 140F, no DW supplementary electric water heating. Scenario 2) Gas DHW @ 110F, DW adds electric energy to raise 10 gallons of 110F water to 140F. The difference in total energy usage between these two scenarios would seem to answer the "which is more efficient" question.

I want a full report on my desk in the morning:-).

Also, did a careful read of your Job Description (above) and am intruigued by your consideration of the effects of interior thermal mass on set back. Would like to discuss that further. Also, could you post a bett version of the chart. Even at 400%, I can't make out the text.

Be Well!
Comment by James White on November 18, 2010 at 3:56pm
I'm not sure how building simulations would answer the question you are asking about domestic hot water.
Comment by Steve Waclo on November 18, 2010 at 1:31pm
Hello James!

Things appear rather quiet over here in Building Simulations, so I thought I might stir up some discussion on the subject of DHW storage temps, as they apply to dishwasher usage. Cruise on over to "Top-10 just launched" on the home page under Forums and go down to "comments" where J.C. and I went somewhat off topic with a discussion of DHW temps. I'm reasonably sure simulations would support maintaining DHW @ 115-120 F, and using electric heat in the DW to boost the temp as the most energy efficient approach, but have found no difinitive study. I suspect this issue has been settled, but would appreciate your thoughts and the results of any simulations you may have run or encountered.
 

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