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Example 1: Energy Code Baseline Comparison

Compare ASHRAE 90.1 System 3 (PSZ-AC) vs System 7 (VAV) for a commercial building.

Scenario

An engineer needs to evaluate which baseline HVAC system produces lower energy use for a 10-zone office. This is a common ASHRAE 90.1 Appendix G workflow.

Prompt

Create a baseline model with ASHRAE System 3, set the Chicago weather file, and run a simulation. Then do the same with System 7 and compare the EUI.

Tool Call Sequence

System 3 (PSZ-AC)

1. create_baseline_osm(name="office_sys3", ashrae_sys_num="03")
2. load_osm_model(osm_path=<returned path>)
3. set_weather_file(epw_path="/inputs/Chicago.epw")
4. add_design_day(name="Chicago Heating 99.6%",
     day_type="WinterDesignDay", month=1, day=21,
     dry_bulb_max_c=-20.6, dry_bulb_range_c=0.0)
5. add_design_day(name="Chicago Cooling .4%",
     day_type="SummerDesignDay", month=7, day=21,
     dry_bulb_max_c=33.3, dry_bulb_range_c=10.7)
6. save_osm_model(save_path="/runs/office_sys3.osm")
7. run_simulation(osm_path="/runs/office_sys3.osm", epw_path="/inputs/Chicago.epw")
8. get_run_status(run_id=<returned id>)   # poll until "success"
9. extract_summary_metrics(run_id=<id>)   # EUI, energy by fuel, unmet hours

System 7 (VAV w/ Reheat)

Repeat steps 1-9 with ashrae_sys_num="07".

Compare

The AI compares:

  • EUI (kBtu/ft2/yr) — total energy use intensity
  • Heating/cooling energy — fuel breakdown
  • Unmet hours — comfort compliance

Key Tools Used

Tool Purpose
create_baseline_osm Creates 10-zone model with ASHRAE system
set_weather_file Attaches EPW to the model
add_design_day Heating/cooling design conditions for HVAC sizing
run_simulation Creates OSW and runs EnergyPlus
extract_summary_metrics Extracts EUI and unmet hours

ASHRAE Baseline Systems Reference

System Type Typical Use
01 PTAC Hotels, small offices
03 PSZ-AC Small commercial (<25,000 sqft)
05 Packaged VAV Medium commercial
07 VAV w/ Reheat Large commercial (>150,000 sqft)

Integration Test

See tests/test_example_workflows.py::test_workflow_baseline_with_weather

The integration test runs an actual EnergyPlus simulation (sizing period) and verifies successful completion with metrics extraction.