Update Infiltration.tsv based on the Residential Diagnostics Database.

[afontani]

Pull Request Description

Companion PR: resstock-estimation #20

The purpose of this pull request is to diversify and update the infiltration housing characteristic. Currently, infiltration is based on the regression from Chan et al. (also based on LBL ResDB). As the regression produces a single infiltration value for a given set of input parameters, the probability distributions specified in the Infiltration.tsv are binary (only 0 and 1). In reality, the distributions are more continuous.

In this pull request, the Infiltration.tsv has been updated with data from the Residential Diagnostics Database (ResDB). The cumulative distribution functions (CDFs) for air change at 50 Pa (ACH50) have been downloaded from their website. Each CDF from the website was fit with a lognormal distribution. The fitted lognormal distribution is then used to assign probabilities into the infiltration bins in ResStock.

Assumptions

It is worth pointing out a few of the assumptions in the distributions.

• The CDFs are for Single-Family Detached homes only. However, ResStock currently does not distinguish infiltration rates between building types.
• Data from certain IECC climate zones were copied to other climate zones. IECC climate zone 2A was copied to 1A. IECC climate zone 6A was copied to 7A. IECC climate zone 6B was copied to 7B.
• The ResStock vintage bins are more refined than the bins in ResDB. As a result certain decade bins had to be copied to other bins. CFDs from the 1950s were copied to the 1940s and the <1940. CFDs from the 2000s were copied to the 2010s.
• Homes are assumed to not be Weatherization Assistance Program (WAP) qualified and not ENERGY STAR certified.
• When obtaining the CDFs, the floor area value was set to be the total_ffa and unit_ffa for the Geometry Floor Area characteristic in options_lookup.tsv.

Checklist

Not all may apply:

• Unit tests have been added or updated
• All rake tasks have been run, and pass
• Documentation has been modified appropriately
• Any new options are added to project_testing
• project_testing runs without any failures
• No unexpected regression test changes
• All tests are passing (green) on circleci
• The changelog has been updated appropriately
• This branch is up-to-date with master

For more information on how to perform these checklist items, see the documentation's Advanced Tutorial.

[afontani]

Goodness of fit for the lognormal distributions.

After scraping the data from ResDB, the figure attached have some quality metrics on the goodness of fit for the lognormal distributions. The error is the L2 distance between the fitted and the data from ResDB. The maximum error is 6.4%.

[afontani]

Dependency Selection

ResDB has a lot of different values that could be a dependency in the Infiltration.tsv file.

• Vintage
• Geometry Foundation Type
• Geometry Floor Area
• Geometry Stories
• IECC Climate Zone

Using each of these as a dependency would result in a file of approximately 100k rows. To reduce the number of rows (and thus the number of dependencies), an analysis was performed to quantify their contribution towards modifying the probability distributions. For each dependency, the L2 distance was used to quantify the amount the dependency changes the distribution. The following algorithm was used.

1. Calculate the average distribution for the USA using the bins in the Infiltration.tsv.
2. For each dependency candidate
   a. Add a dependency
   b. Quantify how much the distribution changed when adding the dependency.
   c. Remove the dependency
3. Select the dependency that changes the average distribution the largest.
4. Repeat steps 2-3 until there are no other dependencies.

This process gives a ranked list of the dependencies and their importance to probabilities in the housing characteristic. Below is a table of the distances (larger is better) for the current housing characteristic in master and the new housing characteristic based on ResDB.

The values from the current version in master are larger because of the binary nature of the numbers.

New Dependencies

The dependencies chosen for the new tsv are:

• Vintage
• Geometry Floor Area
• ASHRAE IECC Climate Zone 2004.

The parameters that were not selected, their PDFs are averaged. This selection reduces the number of rows to ~12,000.

[afontani]

Impact on Infiltration rates

For the US, the median infiltration rate will increase.
Master: 8.84 ACH50
ResDB: 13.07 ACH50

Below is a CDF plot of what is in ResStock now (Master) and the update (ResDB)

[codecov-io]

Codecov Report

Merging #427 into master will increase coverage by 16.09%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #427       +/-   ##
===========================================
+ Coverage   77.32%   93.41%   +16.09%     
===========================================
  Files          86      168       +82     
  Lines       28360    49389    +21029     
===========================================
+ Hits        21928    46139    +24211     
+ Misses       6432     3250     -3182     

Impacted Files	Coverage Δ
...Coil/tests/process_central_system_fan_coil_test.rb	91.84% <0.00%> (ø)
...ate_residential_geometry_from_floorspacejs_test.rb	100.00% <0.00%> (ø)
project_testing/tests/test.rb	84.61% <0.00%> (ø)
...ts/process_constructions_windows_skylights_test.rb	100.00% <0.00%> (ø)
...eport/tests/construction_properties_report_test.rb	100.00% <0.00%> (ø)
measures/TimeseriesCSVExport/measure.rb	93.43% <0.00%> (ø)
...ricsReport/tests/resilience_metrics_report_test.rb	98.26% <0.00%> (ø)
measures/QOIReport/measure.rb	34.13% <0.00%> (ø)
...s/process_central_system_boiler_baseboards_test.rb	100.00% <0.00%> (ø)
...sts/process_two_speed_air_source_heat_pump_test.rb	100.00% <0.00%> (ø)
... and 156 more

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