Building Energy Models Can Be Automatically Adjusted To Fit Data

Date: 
October 12, 2010 - 12:00pm
Location: 
90-3122

To create a detailed building energy model, the modeler must choose dozens or hundreds of parameter values to describe the thermal properties of the building envelope, the efficiency of the heating and cooling system, the temperatures maintained in various parts of the building at various times of day, and so on. Usually some of these values are not precisely known. Typically, a modeler makes her best guesses, runs the models, compares the model output to data --- which typically includes heating, cooling, total power, and room temperatures as a function of time --- and attempts to adjust the model to better fit the data. This hand-tuning can be quite difficult and time-consuming. The speakers have created software tools, collectively known as Software for Tuning Energy Models (STEM), that largely automate model tuning. It has been applied only to Energy Plus but could be used with other building energy modeling programs. STEM adjusts parameter values, within modeler-determined limits, to minimize an error metric that can include almost any available building data; typically, this is a combination of the root-mean-squared errors in cooling and heating energy, lighting, plug loads, and room temperatures. A parallel version of the software, running at NERSC, can optimize 70 parameters for a season-long Energy Plus run of a large building (the UC Merced Classroom and Office Building) with complicated solar shading in about 24 hours of clock time; on a single-processor machine, such a large optimization takes about a week. Results are much faster when working with just 5 or 10 parameters. In this talk, we will discuss the benefits and limitations of the software, with examples from the UC Merced Classroom and Office Building. We will discuss approaches to dealing with unknowns such as schedules and occupancy. We will also touch on issues such as overfitting and model misspecification errors.

Add event to Google Calendar

Announcement List

To be added to our seminar annoucement list please, email the ETA Seminars Team. Seminars can change witout noticed, the best way to stay informed is to join our seminar email list. 

Site Access

For site access please email your request to etaseminars@lbl.gov. To arrive at Building 90 via the LBNL shuttle, take "Blue Uphill". Click here for the shuttle schedule. To ensure your site access is set-up send your request 36 hours in advance of the seminar.

Remote Access

Not able to attend in person? Remote participants can use ReadyTalk Audio & Net conference to phone in to listen, while viewing the presentation via the ReadyTalk site.

Web Access Code: 4864835

USA & Canada call-in number:
1 (866) 740-1260
Access Code: 4864835#

International callers:
Please visit this website to see if a toll-free call-in number is available for your international location.

If not, you will need to pay for the call yourself and use this phone number:

(303) 248-0285.