Microclimate in Underhill
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Peter Duval
Mar 9, 2016, 6:18:42 PM3/9/16
to underhillene...@gmail.com (Google Groups)
I attended the Vermont’s Changing Climate presentation at DRML, 19 February. This spurred me to write about my interest in microclimate in Underhill and ask the state climatologist for suggestions. Here is the write-up:
I am interested in finding out more about microclimate (and weather extremes) for different areas of Underhill, so that we can give good siting and orientation advice for buildings and solar PV systems.
Solar farm and building energy modeling software, such as EnergyPlus (https://energyplus.net/), use Typical Meteorological Year (TMY) data from the National Renewable Energy Lab (NREL). While I suspect that many builders would say that because there are some many variables in the operation of buildings, rules of thumb are good enough, new homes are so energy efficient that subtle differences in siting and orientation could make a big difference in the performance of a building (Passivhaus buildings have a peak load of 10W/m^2 of floor area — and Passivhaus is no longer the best available building standard).
"The TMY data sets hold hourly values of solar radiation and meteorological elements for a 1- year period. Their intended use is for computer simulations of solar energy conversion systems and building systems to facilitate performance comparisons of different system types, configurations, and locations in the United States and its territories. Because they represent typical rather than extreme conditions, they are not suited for designing systems to meet the worst-case conditions occurring at a location.” — Users Manual for TMY3 Data Sets, http://www.nrel.gov/docs/fy08osti/43156.pdf
I think that what I want to do is take a TMY file (Burlington or Montpelier) that is similar to Underhill, and then apply some transformation to the file that makes it better represent the microclimate of specific locations (say reduce summer temperatures by some constant offset, or reduce winter irradiance by some factor). I wish I knew the proper terminology for this kind of fitting, I don’t think “calibration” is quite right.
Or, maybe a station, say at Proctor Maple Research Center, has enough data to create a TMY file from scratch.
The sort of questions I would like to be able to answer:
Can we predict what future microclimate and weather will be like? 30 years ahead? 50 years? 100 years?
Are TMY files adequate for the task? Perhaps multiple years are needed to represent weather variability.
Can we do a better job estimating the annual output of a solar farm? (One array is performing 20% below expectation, on the barn roof at the end of Krug Rd.)
Can we recommend areas of town that would be good sites for building?
Can we offer building orientation optimization for a particular site? (“Sol-air" orientation is not necessarily due south -- Olgyay, V., and A. Olgyay. "Theory of sol-air orientation." Archit. Forum;(United States). Vol. 100. No. 3. 1954.)
Can we anticipate different wind in the future? (Pleasant Valley has high winds now.)
Can we improve PV orientation to optimize for both the time-of-day price of electricity and the local insolation/irradiance?
Can we identify the best sites and orientations (in terms of hourly production) for a PV farm?
Can we derive new rules-of-thumb from the optimizations? (There are already suggestions that east and west pitched fixed PV arrays are becoming more valuable than south facing arrays.)
In researching this question, I did come across a paper that describes constructing TMY files for custom locations, but it is a commercial service and it is not clear if this actually became regular product. (http://www.weatheranalytics.com/images/uploads/SimBuild_2012.pdf)
And I found some documents about future typical meteorological years:
http://www.ibpsa.org/proceedings/BS2013/p_2102.pdf
http://www.ventanaws.org/pdf/about_research/CECpublishedReport.pdf
I also found a presentation that included a mention of future year data: "Produce future year weather files for all 88 locations by merging the historical data with the regional and global climate changes projected by Global Circulation Models” — http://www.energy.ca.gov/title24/2013standards/prerulemaking/documents/2010-11-16_workshop/presentations/06-Huang-Weather_Data.pdf
I am interested in finding out more about microclimate (and weather extremes) for different areas of Underhill, so that we can give good siting and orientation advice for buildings and solar PV systems.
Solar farm and building energy modeling software, such as EnergyPlus (https://energyplus.net/), use Typical Meteorological Year (TMY) data from the National Renewable Energy Lab (NREL). While I suspect that many builders would say that because there are some many variables in the operation of buildings, rules of thumb are good enough, new homes are so energy efficient that subtle differences in siting and orientation could make a big difference in the performance of a building (Passivhaus buildings have a peak load of 10W/m^2 of floor area — and Passivhaus is no longer the best available building standard).
"The TMY data sets hold hourly values of solar radiation and meteorological elements for a 1- year period. Their intended use is for computer simulations of solar energy conversion systems and building systems to facilitate performance comparisons of different system types, configurations, and locations in the United States and its territories. Because they represent typical rather than extreme conditions, they are not suited for designing systems to meet the worst-case conditions occurring at a location.” — Users Manual for TMY3 Data Sets, http://www.nrel.gov/docs/fy08osti/43156.pdf
I think that what I want to do is take a TMY file (Burlington or Montpelier) that is similar to Underhill, and then apply some transformation to the file that makes it better represent the microclimate of specific locations (say reduce summer temperatures by some constant offset, or reduce winter irradiance by some factor). I wish I knew the proper terminology for this kind of fitting, I don’t think “calibration” is quite right.
Or, maybe a station, say at Proctor Maple Research Center, has enough data to create a TMY file from scratch.
The sort of questions I would like to be able to answer:
Can we predict what future microclimate and weather will be like? 30 years ahead? 50 years? 100 years?
Are TMY files adequate for the task? Perhaps multiple years are needed to represent weather variability.
Can we do a better job estimating the annual output of a solar farm? (One array is performing 20% below expectation, on the barn roof at the end of Krug Rd.)
Can we recommend areas of town that would be good sites for building?
Can we offer building orientation optimization for a particular site? (“Sol-air" orientation is not necessarily due south -- Olgyay, V., and A. Olgyay. "Theory of sol-air orientation." Archit. Forum;(United States). Vol. 100. No. 3. 1954.)
Can we anticipate different wind in the future? (Pleasant Valley has high winds now.)
Can we improve PV orientation to optimize for both the time-of-day price of electricity and the local insolation/irradiance?
Can we identify the best sites and orientations (in terms of hourly production) for a PV farm?
Can we derive new rules-of-thumb from the optimizations? (There are already suggestions that east and west pitched fixed PV arrays are becoming more valuable than south facing arrays.)
In researching this question, I did come across a paper that describes constructing TMY files for custom locations, but it is a commercial service and it is not clear if this actually became regular product. (http://www.weatheranalytics.com/images/uploads/SimBuild_2012.pdf)
And I found some documents about future typical meteorological years:
http://www.ibpsa.org/proceedings/BS2013/p_2102.pdf
http://www.ventanaws.org/pdf/about_research/CECpublishedReport.pdf
I also found a presentation that included a mention of future year data: "Produce future year weather files for all 88 locations by merging the historical data with the regional and global climate changes projected by Global Circulation Models” — http://www.energy.ca.gov/title24/2013standards/prerulemaking/documents/2010-11-16_workshop/presentations/06-Huang-Weather_Data.pdf
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