Display Design Temperature, and implement the Design Temperature Override feature

[AdamFinkle]

Background

The Design Temperature depends on the home's address. Somewhere in our code, we do an external query to find the U.S. county in which a home is located based on its address. Then we look up the heating design temperature in a table derived from an EnergyStar document that specifies the heating design temperature for each county in the U.S. We'll call that value the County-Level Design Temperature. The EnergyStar source explains that they used the lowest heating design temperature among all weather stations within the county which turns out to be very conservative, i.e. colder than necessary in many cases. To work around this, we need to provide a field for users to override the County-Level Design Temperature. We'll call this value the Design Temperature Override.

UI specification

• There should be a new heading Heating Design Temperature below the Calculate button and above the heading Heat Load Analysis. There should be a help question-mark icon at the end of this heading, help text specified at the end of this write-up. This heading will appear after the user clicks Calculate, or whenever analysis results are displayed. The reason for displaying it in this location is that this value depends on the user having already entered the home's address. There should
• Underneath the above-specified heading, display:
  County-Level Design Temperature <value in degF> °F <horizontal space> Design Temperature Override entry-field
• The font size and weight for the above-specified row should be the same as the fields displayed under the Heat Load Analysis heading.
• The "entry-field" should be an editable field that allows a number in the range -10 to 32, with the tip inside the field "Enter a value in the range -10 to 32". Underneath the field, display the tip "If a value is entered, it will be used in place of the County-Level Design Temperature"
• The

And here's how this should work from a calculation perspective:

• If the Design Temperature Override field is empty, the Rules Engine should use the County-Level Design Temperature.
• If the Design Temperature Override field has a valid value, the Rules Engine should use that value in place of the County-Level Design Temperature
• If the Design Temperature Override contains an invalid value, display an error message "The entered value is not valid" in the same way as other error messages on this form.
• Both the County-Level Design Temperature and a Design Temperature Override value (either valid or null) should be saved with other analysis results that are saved with the case.

Help Text

The heating design temperature is the coldest outdoor temperature for which the heating system should be capable of supplying sufficient heat to maintain an indoor temperature of 70°F. The default is to use a County-Level Design Temperature obtained from an ENERGY STAR guide. However, there are sometimes reasons to override the default value by entering a different value in the Design Temperature Override field, including:

• The user wants to compare the output from this tool with a Manual J analysis. In this case, enter an override value that matches the heating design temperature used in the Manual J analysis
• The user judges that the default value is too low or too high. In general, values obtained from the ENERGY STAR guide appear to be very conservative (lower than necessary) because the guide is based on the lowest ASHRAE 99% heating design temperature among all weather stations within a county. The guide cites an EPA recommendation to use the ASHRAE 99% heating design temperature for the weather station that is geographically closest to a home, which will often give a higher value when there are multiple weather stations within a county.
• A different value specified by the local jurisdiction (uncommon)

Implementation

I have the impression that the rules engine already supports a design temperature override. If so, the main work here is to implement the UI, make sure the override value gets passed through to the rules engine, and save the value in the database.

[thadk]

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[thadk]

@wvansteen here’s the folder with the python code that looks up the reference design temp based on the user’s county (code) https://github.com/codeforboston/home-energy-analysis-tool/tree/main/design_temp

Steve’s point why this is a must-have for launch was that the design temps of this lookup table are quite different from the simpler lookup in the spreadsheet his users are familiar with.

I’ll try to insert the design temp pyodide code:

home-energy-analysis-tool/heat-stack/app/pycode/roundtrip_analytics.py

Lines 17 to 20 in b1829d5

	design_temp_looked_up = helpers.get_design_temp(state_id, county_id)
	# expect 1 for middlesex county: print("design temp check ",design_temp_looked_up, state_id, county_id)
	summaryInput = HeatLoadInput(
	**summaryInputFromJs, design_temperature=design_temp_looked_up

See also how one of the visualizations would ideally be affected by design temp override in now-closed #313

[thadk]

Hi @stevebreit , Here is an example of what appears after the user modifies the address:

We probably should put a placeholder area for when the address hasn't been changed yet so the user is not surprised when it appears.

[stevebreit]

Rather than including "is 5F" in the label, I'd prefer a separate label with larger font below that which reports the value followed by the Fahrenheit symbol. The appearance should be similar to the way we display results after full calculation. I'm attaching a screen capture to show what I mean. In this screen capture, I yellow highlighted a reported value, and that's how it should look here, but perhaps a smaller font to be consistent with the font size in the editable fields.

Also, remove the tip that says "If a value is entered..." underneath the "Design Temperature Override" field, add a tip underneath the the displayed value of the County-Level Design Temperature that says "This value is calculated from the address and will be used unless an override value is entered."