d4f6ff0f2f
SAP 10.2 Table 3 (PDF p.160) "Primary circuit loss" verbatim:
"Primary circuit loss applies when hot water is heated by a heat
generator (e.g. boiler) connected to a hot water storage vessel
via insulated or uninsulated pipes (the primary pipework)."
The spec rule does NOT restrict to Table 4b gas/oil boilers — any
boiler connected to a cylinder via primary pipework incurs the loss.
The cert's `water_heating_code` is the discriminator:
- WHC=901/902/914 (HW from main heating system) + wet boiler +
cylinder → primary loss applies (back-boiler / wet boiler heats
cylinder via primary loop).
- WHC=903 (HW from a separate electric immersion / secondary) → no
primary loss even when the main is a wet boiler.
Pre-slice `_primary_loss_applies` only covered Table 4b gas/oil boiler
codes (101-141). Table 4a solid-fuel boiler codes 151-161 (manual /
auto / range-cooker boilers, closed room heater + back-boiler, open
fire + back-boiler, wood pellet + back-boiler) fell through and
primary loss silently went to zero — under-counting §5 (72) water-
heating internal gain by ~74 W cohort-wide for every WHC=901 solid-
fuel back-boiler variant.
Worksheet evidence on the 001431 corpus (all age G, same cylinder):
- solid fuel 2 (code 158, WHC=901): ws (59) ≈ 505 kWh/yr → apply
- solid fuel 3 (code 160, WHC=901): ws (59) ≈ 643 kWh/yr → apply
- solid fuel 5 (code 153, WHC=903): ws (59) = 0 → skip
- solid fuel 4..11 (633/636 non-boilers, WHC=903): skip
The fix:
- `_primary_loss_applies(...)` gains a `water_heating_code: Optional[int]`
parameter (default None for back-compat with synthetic tests).
- New branch after the Table 4b fallback: `_is_wet_boiler_main(main)`
+ `water_heating_code in _WATER_INHERIT_FROM_MAIN_CODES` → True.
- Call site `_primary_loss_override` passes
`epc.sap_heating.water_heating_code`.
Heating-systems corpus impact:
- solid fuel 3 (code 160, WHC=901): +1.31 → +0.30 SAP
PE -918.6 → -214.3 kWh/yr
- solid fuel 2 (code 158, WHC=901): +2.77 → +2.06 SAP
PE -1241.7 → -754.1 kWh/yr
- All other variants: unchanged
SF2 doesn't fully close because the worksheet's (59) is winter-only
(0 in summer) but the cascade applies the year-round Table 3 formula
via `_separately_timed_dhw=True` (cylinder + non-electric HW fuel).
Remaining residual is a follow-up — likely a
`_separately_timed_dhw=False` rule for solid-fuel back-boilers (HW
timing tied to the room fire, not separately programmed).
Pyright net-zero (43 → 43). Extended handover suite: 895 → 896 pass.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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| .devcontainer | ||
| .github/workflows | ||
| .idea | ||
| .vscode | ||
| applications | ||
| asset_list | ||
| backend | ||
| backlog | ||
| datatypes | ||
| deployment/terraform | ||
| docs/adr | ||
| domain | ||
| epr_data_exports | ||
| etl | ||
| infrastructure | ||
| model_data/requirements | ||
| orchestration | ||
| recommendations | ||
| repositories | ||
| scripts | ||
| sfr/principal_pitch | ||
| survey_report | ||
| tests | ||
| utilities | ||
| utils | ||
| .coveragerc | ||
| .dockerignore | ||
| .gitignore | ||
| __init__.py | ||
| ara_backend_design.md | ||
| BaseUtility.py | ||
| CLAUDE.md | ||
| conftest.py | ||
| CONTEXT.md | ||
| devcontainer.sh | ||
| Dockerfile.test | ||
| Dockerfile.test.dockerignore | ||
| Makefile | ||
| MEMORY.md | ||
| package-lock.json | ||
| package.json | ||
| pyproject.toml | ||
| pyrightconfig.json | ||
| pytest.ini | ||
| README.md | ||
| run_lambda_local.sh | ||
| serverless.yml | ||
| test.requirements.txt | ||
| tox.ini | ||
| UBIQUITOUS_LANGUAGE.md | ||
Model Repository
This repository contains the code pertaining to the development of the data science and machine learning products being utilised by Hestia.
The different folders in this repository relate to services that can be used independently, or can be imported and used as part of a larger application
Getting Started
Prerequisites
Dev Container Setup
This repo uses a Docker Compose-based dev container. The model-backend service joins a shared-dev Docker network so it can communicate with other local services (e.g. a frontend container) running on your machine.
VS Code users: The initializeCommand in devcontainer.json creates the shared-dev network automatically before the container starts. No manual step required — just open the repo and select Reopen in Container.
Non-VS Code / CI workflows: Run the following once before starting the container:
make dev-setup
This is idempotent and safe to re-run if the network already exists.
Folders
backend/
This folder contains the code for the fastapi backend service, which provides an interface to much of the functionality in this repository, for the frontend
model_data/
This folder contains related to the reading and preparation of assessment model data, including pulling out epc attributes
Testing
All tests can be run, against the configuration in pytest.ini running
pytest
This will run the complete panel of tests and report on coverage in the locations specified by the pytest.ini file.
To run tests in a specific service, e.g. inside of model_data, simply run
pytest --cov-config=model_data/.coveragerc --cov=model_data
This will produce the test results and coverage reports