[Bldg-sim] Calibrated Simulations & ASHRAE G14

[Justin Spencer]

Hayes --
When calibrating residential models, I find that tweaking things like shade
schedules, internal mass, and solar mass coupling is quite helpful. You
also need to implement some natural ventilation if that's happening. Also,
you should always distrust your measurements until you have a better feel
for what the error bound is like. How did you measure ACH? With a blower
door? You'll be lucky to have the infiltration component right to within
30%. Do your wall constructions compensate for two dimensional heat
transfer effects? How well do you think you have these quantified? What
about your ducts? And your air conditioning equipment? Don't overconstrain
yourself.

Remember also that you are using a simulation model, not actually solving
the complete set of heat transfer equations. The model is just a model --
it won't calculate the correct total energy consumption unless
you calibrate it to do so. Remember that different simulation software
modeling the same highly simplified building test cases vary by 10-20% or
more (see BESTEST results comparing ESP-R, EnergyPlus and various DOE2
generations). Simulation models work great for showing relative differences
in energy consumption, not so much for absolute energy consumption.

My general approach for residential building calibration looks something
like this:

   1. Build out your model using your best available data.
   2. Nail the lighting and equipment loads.
   3. Nail the hot water loads.
   4. Compare your annual and monthly heating and cooling consumption to
   measured and look at the direction each need to move, then start making
   tweaks to your model. I try to turn all of knobs that have similar impacts,
   and keep them all in what looks like a reasonable range.
   5. Take a look at the hourly profiles for different seasons and look at
   interactions of solar, mass, and natural ventilation. You can tweak these
   to shift your shape some.
   6. Last, I do what feels like the big cheat, which is to start messing
   with the daily and monthly thermostat schedules to get things fine-tuned. I
   can generally keep things within a degree or two of measured temps. This
   step will almost certainly be necessary to get your results lined up.

In the end, I think it's fairly difficult to get a residential model
calibrated to the hourly CV(RMSE) of 30% for the HVAC end uses, even for an
experienced residential modeler. If your target is based on total
consumption, then you should not have a problem if the non-HVAC loads are
smooth enough. I don't know for sure, but it appears Guideline 14
simulation guidance was not developed with calibrating to a single
residential single family home in mind. It's not something people really
do. We calibrate to models of aggregations of homes when we're evaluating
residential energy efficiency programs for utilities.

I'd be very curious to hear about other calibration methods/standards used
by experts in the field. Prof. Haberl's response was great.


On Wed, Jan 4, 2012 at 7:58 PM, Jeff Haberl <jhaberl at tamu.edu> wrote:

> Hello Hayes,
>
> I helped write the calibrated simulation section of Guideline 14,
> including the new Guideline 14, which is about to go out for public review.
> I also participated in the NEMVP, IPMVP.
>
> Currently, the Guideline 14 committee is completing the final draft and
> will meet at the Chicago ASHRAE meeting for final discussion before it goes
> out (Dennis Landsberg is the committee chair, and I've cc'd others to chime
> in). So, if you wait for a little bit, you'll be able to get the public
> review draft of the new Guideline 14, which contains lots of new, good
> stuff.
>
> You'll also find useful material in the IPMVP (latest version), the ASHRAE
> Performance Metric Protocols, and the ASHRAE Handbook of Fundamentals,
> Chapter 19, 2009. Dr. Reddy also now has a great text book on statistical
> or inverse methods for engineers.
>
> In addition, here are some of papers that our Lab has published that
> address the issue of calibrated simulation. You'll find most of these
> on-line at our web site:
>
> Song, S., Haberl, J. 2008. “A Procedure for the Performance Evaluation of
> a New Commercial Building: Part I – Calibrated As-built Simulation”,
>  ASHRAE Transactions-Research, Vol. 114, Pt. 2, pp. 375-388 (June ).
>
> Song, S., Haberl, J. 2008. “A Procedure for the Performance Evaluation of
> a New Commercial Building: Part II – Overall Methodology and Comparison of
> Results”,  ASHRAE Transactions-Research, Vol. 114, Pt. 2, pp. 389 – 403
> (June).
>
> Haberl, J., Culp, C., Co-authors, “Chapter 27: Monitoring and
> Verification,” Energy Management Handbook, 5th Edition, Wayne Turner,
> Editor, Fairmont Press, New York (2005), pp. 715 – 762.
>
> Im, P., Haberl, J. 2010. “Analysis of the Energy Savings Potential in K-5
> Schools in Hot and Humid Cliamtes: Application of High Performance Measures
> and Renewable Energy Systems”, Proceedings of the SIMBUILD 2010 Conference,
> International Building Performance Simulation Association – USA, New York,
> N.Y. (August).
>
> Cho, S., Haberl, J. 2008. “Validation of the eCALC Commercial
> Code-Compliant Simulation Versus Measured Data from an Office Building in a
> Hot and Humid Climate”, Proceedings of the 16th  Symposium on Improving
> Building Systems in Hot and Humid Climates, Texas A&M University, Dallas,
> Texas, published on CD ROM (December).
>
> Im, P., Haberl, J. 2008. “Analysis of the Energy Savings Potential in K-5
> Schools in Hot and Humid Climates”, Proceedings of the 16th  Symposium on
> Improving Building Systems in Hot and Humid Climates, Texas A&M University,
> Dallas, Texas, published on CD ROM (December).
>
> Haberl, J., Davies, H., Owens, B., Hunn. B. 2008. “ASHRAE’s New
> Performance Measurement Protocols for Commercial Buildings”, Proceedings of
> the 8th International Conference for Enhanced Building Operation”, Berlin,
> Germany, published on CD ROM (October).
>
> Kissock, K., Haberl, J., Claridge, D. 2003. “Inverse Model Toolkit
> (1050RP): Numerical Algorithms for Best-Fit Variable-Base Degree-Day and
> Change-Point Models,” ASHRAE Transactions-Research, Vol. 109, Pt. 2, pp.
> 425-434.
>
> Haberl, J., Claridge, D., Kissock, K. 2003. “Inverse Model Toolkit
> (1050RP): Application and Testing, ASHRAE Transactions-Research, Vol. 109,
> Pt. 2, pp. 435-448, 2003.
>
> Sreshthaputra, A., Haberl, J., Andrews, M. 2004. “Improving Building
> Design and Operation of a Thai Buddhist Temple,” Energy and Buildings, Vol.
> 36, pp. 481-494.
>
> Abushakra, B., Haberl, J., Claridge, D. 2004. “Overview of Literature on
> Diversity Factors and Schedules for Energy and Cooling Load Calculations
> (1093-RP),” ASHRAE Transactions-Research, Vol. 110, Pt. 1 (February), pp.
> 164-176.
>
> Claridge, D., Abushakra, B., Haberl, J. 2003. “Electricity Diversity
> Profiles for Energy Simulation of Office Buildings (1093-RP),” ASHRAE
> Transactions-Research, Vol. 110, Pt. 1 (February), pp. 365-377.
>
> Reddy, T., Haberl, J., Elleson, J. 1999. “Engineering Uncertainty Analysis
> in the Evaluation of Energy and cost Savings of Cooling System Alternatives
> Based Upon Field Monitored Data,” ASHRAE Transactions-Research, Vol. 105,
> Pt.. 2, pp. 1047 - 1057 (June).
>
> Haberl, J., Bou-Saada, T. 1998. “Procedures for Calibrating Hourly
> Simulation Models to Measured Building Energy and Environmental Data,” ASME
> Journal of Solar Energy Engineering, Vol. 120, pp. 193 - 204 (August).
>
> Haberl, J., Abbas, M. 1998. “Development of Graphical Indices for Viewing
> Building Energy Data: Part 2,” ASME Journal of Solar Energy Engineering,
> Vol. 120, pp. 162 - 167 (August).
>
> Haberl, J., Abbas, M. 1998. “Development of Graphical Indices for Viewing
> Building Energy Data: Part 1,” ASME Journal of Solar Energy Engineering,
> Vol. 120, pp. 156 - 161 (August).
>
> Haberl, J., Thamilseran, S., Reddy, T., Claridge, D., O’Neal, D., Turner,
> D. 1998. “Baseline Calculations for Measuring and Verification of Energy
> and Demand Savings in a Revolving Loan Program in Texas,” ASHRAE
> Transactions-Research, Vol. 104, Pt. 2, pp. 841 - 858 (June).
>
> Haberl, J., Thamilseran, S. 1998. “Predicting Hourly Building Energy Use:
> The Great Energy Predictor Shootout II: Measuring Retrofit Savings,” ASHRAE
> Journal, Vol. 40, No. 1, pp. 49 - 56 (January).
>
> Reddy, T., Haberl, J., Saman, N., Turner, W., Claridge, D., Chalifoux, A.
> 1997. “Baselining Methodology for Facility-Level Monthly Energy Use - Part
> 2: Application to Eight Army Installations,” ASHRAE Transactions-Research,
> Vol. 103, Pt. 2, pp. 348 - 359 (June).
>
> Reddy, T., Haberl, J., Saman, N., Turner, W., Claridge, D., Chalifoux, A.
> 1997. “Baselining Methodology for Facility-Level Monthly Energy Use - Part
> 1: Theoretical Aspects,” ASHRAE Transactions-Research, Vol. 103, Pt. 2, pp.
> 336 - 347 (June).
>
> Ruch, D., Chen, L., Haberl, J., Claridge, D. 1993. “A Change-Point
> Principal Component Analysis (CP/PCA) Method for Predicting Energy Usage in
> Commercial Buildings: The PCA Model,” ASME Journal of Solar Energy
> Engineering, ASME, New York, N.Y., Vol. 115, pp. 77 - 84 (May).
>
> Haberl, J., Bronson, D., Hinchey, S., O'Neal, D. 1993. “Graphical Tools to
> help Calibrate the DOE-2 Simulation Program to Non-weather Dependent
> Measured Loads,” ASHRAE Journal, Vol. 35, No. 1, pp. 27 - 32 (January).
>
> I also teach calibrated simulation to the students that take my graduate
> simulation class. In a nutshell, you can do so by using the following
> simple rules-of-thumb (these are based on Norford/Hseih's work in N.J.):
>
> 1. Force the electrical loads to equal whatever data you have, i.e.,
> hourly is best, or use daily or monthly (i.e., see the new ASHRAE Research
> Project by Abshakra and Reddy for more on this). Force the occupancy and
> internal loads as well. Shut off infiltration if there is an AHU.
>
> 2. Use real weather data (i.e., roll you own weather file), or use the
> closest TMY or TMY2 or TMY3 files (but do not match the temporal data).
>
> 3. Get the average hourly weekday/weekend electrical profiles to match.
>
> 4. Use daily heating and cooling from the appropriate hourly report vs
> real daily data plotted against average daily temperatures. Turn everything
> on in the simulation (i.e., do not use occupied unoccupied schedules unless
> you're really sure of this).
>
> 5. Look at the results (graphical) and take a good guess at what to tweek,
> repeat 1 - 4 as needed.
>
> 6. Spend a little time as needed to get the envelope described. Use a
> simple structure since systems and plant will change answers by +-100 -
> 500%, versus architectural features that change things by only 20 - 50%.
>
> 7. Ask for help.
>
> Finally, follow the +- differences in Guideline 14 or the IPMVP and don't
> forget that your building could be messed up, which means that your
> simulation will needed to be messed up to match it.
>
> We're currently working on automated calibrated methods for residential,
> with some thoughts about the same for commercial. Others have similar tools
> as well (i.e., see the ASHRAE literature for these).
>
> Hope this helps.
>
> Jeff
>
> 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=)8=?
>
> Jeff S. Haberl, Ph.D.,P.E., FASHRAE..............jhaberl at tamu.edu
>
> Professor............................................................Office
> Ph: 979-845-6507
>
> Department of Architecture.............................Lab Ph:979-845-6065
>
> Energy Systems Laboratory.............................FAX: 979-862-2457
>
> Texas A&M University.....................................77843-3581
>
> College Station, Texas, USA, 77843..................URL:www.esl.tamu.edu
>
> 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=? 8=)8=0
> ________________________________________
> From: bldg-sim-bounces at lists.onebuilding.org [
> bldg-sim-bounces at lists.onebuilding.org] on behalf of Hayes Zirnhelt [
> hzirnhelt at hotmail.com]
> Sent: Wednesday, January 04, 2012 4:26 PM
> To: bldg-sim at lists.onebuilding.org
> Subject: [Bldg-sim] Calibrated Simulations & ASHRAE G14
>
> Hi,
> Does anyone have experience with calibrated simulations? Especially, in
> accordance with ASHRAE guideline 14, or other standards / guidelines.
>
> I've been working on a calibrating and EnergyPlus model to measured gas
> HVAC data for a single family house with extensive monitoring and detailed
> information available and I am finding it very difficult to achieve the <=
> 30% CV RSME that Guideline 14 suggests.
>
> I'm surprised that it is this challenging because I have far more
> information available than what would likely be available in typical
> modelling jobs. Eg. ACH rating, measured ground temperature data, full
> as-built plans, indoor temperature measurements....
>
> So I'm curious to hear about anyone else's experiences with this. Is this
> guideline generally achievable for modellers?
>
> Thanks,
>
> Hayes Zirnhelt
> M.A.Sc <http://m.a.sc/> Candidate, RU Building Science
> B.A.Sc <http://b.a.sc/> Integrated Engineering
> hayes.zirnhelt at ryerson.ca
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