Friday, September 16, 2016

Autotune calibrates models to building use data - YouTube

Autotune calibrates models to building use data - YouTube: "
Ron Allen1 day ago
@Oak Ridge National Laboratory - I have to ask...
1. Is it going through and reshaping the algorithms in the simulation or adjusting 'adjustment' factors?
2. Once it has tuned the calculations - is it the simulation effective for another run?
3. Is the simulation effective to run in other regions?

One example of what throws off simulated data from real data is doors and windows being left open... I am looking for a real, effective simulation to get the metric right based on proposed construction and verified against as-built conditions.

Thnx!
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Oak Ridge National Laboratory5 hours ago
From Joshua New, the lead researcher on the project:

1. Is it going through and reshaping the algorithms in the simulation or adjusting 'adjustment' factors?
Autotune changes 47-470 (based on building type) of the ~3,000 simulation inputs that are required to describe a building. While users can modify for the inputs they care about (infiltration, HVAC, lighting, etc.), the default “uncertain” parameters, referenced as Supplementary Material 1 in the recent Applied Energy article, can be viewed at bit.ly/29J3HHM.
Autotune is simulation-engine agnostic, but is shown in the video as using EnergyPlus. There are other dissertations and ongoing, multi-lab efforts to empirically validate the EnergyPlus simulation engine and further reduce model-form uncertainty by reducing the gap between physics and algorithmic approximations.

2. Once it has tuned the calculations - is it the simulation effective for another run?
Not calculations, but inputs, are calibrated. Once a building model is calibrated to ASHRAE Guideline 14 requirements, the model can be used with greater confidence and with agencies involving tax credits (IRS), performance tradeoffs for building code compliance, and financing (banks).

3. Is the simulation effective to run in other regions? One example of what throws off simulated data from real data is doors and windows being left open... I am looking for a real, effective simulation to get the metric right based on proposed construction and verified against as-built conditions.
Yes, with a couple caveats: (1) Most regional change is accounted for by swapping out the weather file used. Where you get weather data from can impact annual energy use by 7% and monthly heating/cooling loads by over 40%. Buildings codes can change between regions and should be converted in the calibrated model.
Zone-level infiltration impacts due to open doors and windows, as well as more detailed occupancy/equipment schedule characteristics, are large-impact variables that can be calibrated by Autotune.
There is a new technique coming out in less than a year called “hybrid modeling” which can use temperature data from a thermal zone that can also estimate infiltration and thermal mass of the zone. This capability will eventually be added to EnergyPlus."



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