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Khalim Conn-Kowlessar 5c2158e6c4 Slice S0380.171: CHP heat-fraction split for community heating cost
Closes the +£104 cost / +4.5 SAP gap on CH2/CH4 (community heating
with CHP-fed mains-gas / oil boilers) by implementing the RdSAP 10
§C / SAP 10.2 Appendix C (PDF p.58) default heat-fraction split:

  "If CHP (waste heat or geothermal treat as CHP):
   - fraction of heat from CHP = 0.35
   - CHP overall efficiency 75%
   - heat to power ratio = 2.0
   - boiler efficiency 80%"

Verified against the corpus block 9b lodgement: CH2 worksheet (303a)
= 0.3500 + (303b) = 0.6500 + (305) = 1.00 + (306) DLF = 1.45. The
worksheet block 10b cost cascade applies (340a) = (307a) × CHP_price
(Table 12 code 48 = 2.97 p/kWh) + (340b) = (307b) × boiler_price
(Table 12 codes 51-58 = 4.24 p/kWh) with (307a) = 0.35 × (307),
(307b) = 0.65 × (307).

Pre-slice the cascade dispatched single-fuel code 48 (CHP) for every
CHP variant and billed 100% of heat at 2.97 p/kWh, under-charging by
~£104/yr versus the worksheet's 35% × 2.97 + 65% × 4.24 = 3.7945
p/kWh blended rate.

Three layers wired:

1. Datatype — new fields on `MainHeatingDetail`:
   - `community_heating_chp_fraction: Optional[float]`
   - `community_heating_boiler_fuel_type: Optional[int]`
   None on individually-heated dwellings + non-CHP heat networks
   (Boilers-only + Heat-pump networks bill at a single Table 12 code
   via main_fuel_type, unchanged path).

2. Mapper — new `_elmhurst_community_chp_split(community)` helper +
   `_RDSAP_COMMUNITY_CHP_FRACTION_DEFAULT = 0.35` constant. When the
   §14.1 Community Heat Source is "Combined Heat and Power": returns
   (0.35, boiler_fuel_code) where boiler_fuel_code is resolved from
   the §14.1 Community Fuel Type via the existing
   `_ELMHURST_COMMUNITY_BOILER_FUEL_TO_TABLE_12` dispatch (gas → 51,
   oil → 53, coal → 54).

3. Cascade — `_fuel_cost_gbp_per_kwh` now returns
   `chp_frac × CHP_price + (1 - chp_frac) × boiler_price`
   when both new fields are set on Main 1. Per [[feedback-spec-
   citation-in-commits]] the implementation cites RdSAP 10 §C
   verbatim. Non-CHP heat networks + individually-heated certs route
   through the existing single-fuel-code branch unchanged.

5 new AAA tests parametrized over the 5 CH corpus variants in
`test_community_heating_mapper_populates_chp_split_fields` assert
the per-variant (chp_fraction, boiler_fuel_code) populates correctly.

Closures vs pre-S0380.171 residuals (heating-systems corpus block 11b):

  variant            ΔSAP      Δcost      status
  CH1  (Boilers/Gas) +0.5915   -£13.63    unchanged (no CHP split)
  CH2  (CHP/Gas)     +4.50→-0.0076  -£104→+£0.17   ✓ CLOSED
  CH3  (HP/Elec)     +0.5915   -£13.63    unchanged (no CHP split)
  CH4  (CHP/Oil)     +4.50→-0.0076  -£104→+£0.17   ✓ CLOSED
  CH6  (CHP/Coal)    -3.52→-8.03   +£81→+£185     REGRESSED

The CH6 regression is exposed (not caused) by the spec-correct split:
pre-slice CH6 sat at -3.52 SAP / +£81 by coincidence — the cascade's
CHP-only pricing (2.97 p/kWh) cancelled with cascade DLF=1.45
(Table 12c age G default) against the CH6 worksheet's lodged DLF=1.0.
Per [[feedback-software-no-special-handling]] apply the spec-correct
fix uniformly; the pre-fix near-zero was an offsetting-bugs artifact,
not a deliberate non-spec rule.

The CH6 worksheet (306) DLF=1.0 is a cert-side quirk not currently
surfaced through the Summary PDF: CH4 and CH6 §14 lodgements are
IDENTICAL except for Community Fuel Type ("Mineral oil or biodiesel"
vs "Coal"), yet CH6's worksheet (306) = 1.0000 while CH4's = 1.4500.
The Elmhurst engine appears to override DLF for the coal-CHP combo
via a path not visible in the Summary; a follow-up slice will need to
either (a) add a §17 assessor-lodged DLF extractor or (b) extend the
mapper's age-band → DLF dispatch with a community-fuel-specific
override.

CO2 / PE residuals on all 5 CH variants are unchanged — this slice
touches cost only. The CO2 / PE cascade still needs: (1) the CHP
electricity-credit line (worksheet (464)/(466)/(364)/(366) per SAP
10.2 §13b spec — displaced-electricity reduction), (2) community-HP
COP cascade for CH3 (Table 12 code 41 PE/CO2 isn't divided by COP),
and (3) heat-network overall blended-factor (486)/(386) calc.

Test baseline at HEAD: 926 pass + 1 skipped (was 921 + 1 at
predecessor 9f0d23ad). Pyright net-zero on affected files
(epc_property_data.py, mapper.py, cert_to_inputs.py,
test_heating_systems_corpus.py + elmhurst_site_notes.py): 65 → 65.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-06-04 15:40:25 +00:00
.devcontainer pr review, move domain and orhcestration 2026-06-01 14:00:31 +00:00
.github/workflows deploy lambda 2026-06-04 15:32:51 +00:00
.idea scaffolding for ml pipeline 2026-05-16 14:15:56 +00:00
.vscode added utils to allow easier subtask management 2026-03-02 15:15:39 +00:00
applications reformatted to be DDD structure 2026-06-04 14:50:04 +00:00
asset_list redeploy old postcode splitter 2026-05-21 09:46:47 +00:00
backend Slice S0380.171: CHP heat-fraction split for community heating cost 2026-06-04 15:40:25 +00:00
backlog implemented onboarding 2026-04-21 20:23:33 +00:00
datatypes Slice S0380.171: CHP heat-fraction split for community heating cost 2026-06-04 15:40:25 +00:00
deployment/terraform tests files 2026-06-04 11:47:42 +00:00
docs reformatted to be DDD structure 2026-06-04 14:50:04 +00:00
domain Slice S0380.171: CHP heat-fraction split for community heating cost 2026-06-04 15:40:25 +00:00
epr_data_exports allowing carbon and energy otimisation by removing slack 2025-07-31 19:13:16 +01:00
etl booking status 2026-06-01 16:28:47 +00:00
infrastructure tests files 2026-06-04 11:47:42 +00:00
model_data/requirements its working the way khalim wanted wiht postcode and then search that 2026-01-22 15:17:13 +00:00
orchestration reformatted to be DDD structure 2026-06-04 14:50:04 +00:00
recommendations save 2026-05-07 15:55:44 +00:00
repositories reformatted to be DDD structure 2026-06-04 14:50:04 +00:00
scripts feat(ingestion): relocate EpcClientService to infrastructure + SolarRepo (#1133) 2026-06-01 16:28:48 +00:00
sfr/principal_pitch added added historic epc data class with shape 2026-05-08 12:03:35 +00:00
survey_report quidos site notes extraction 2025-02-18 19:49:29 +00:00
tests reformatted to be DDD structure 2026-06-04 14:50:04 +00:00
utilities get rid of comments 2026-05-20 13:21:11 +00:00
utils rename files in sharepoint to desired structure 2026-05-20 16:26:07 +00:00
.coveragerc fixed unit tests 2023-10-05 16:04:12 +01:00
.dockerignore deployment from infrastructure 2026-05-19 12:55:30 +00:00
.gitignore fixed merge conflicts from main 2026-05-26 11:21:09 +00:00
__init__.py added checking for directory before creation and made some minor style changes 2023-08-25 15:21:17 +01:00
ara_backend_design.md refactor: lift-and-shift packages/domain/src/domain/ml → domain/sap10_ml 2026-05-26 13:01:35 +00:00
BaseUtility.py fixed missing task and subtask for single remote assessments 2025-11-27 17:50:26 +00:00
CLAUDE.md fixed merge conflicts from main 2026-05-26 11:21:09 +00:00
conftest.py working on integrating new EPC api into address2UPRN 2026-04-27 11:32:44 +00:00
CONTEXT.md feat(baseline): BaselineOrchestrator + BaselinePerformance aggregate (#1135) 2026-06-01 16:28:48 +00:00
devcontainer.sh add dev container 2026-04-17 14:50:57 +00:00
Dockerfile.test fix: address 22 project-wide test failures from previous sweep 2026-05-26 13:34:51 +00:00
Dockerfile.test.dockerignore deployment from infrastructure 2026-05-19 12:55:30 +00:00
Makefile adding to dev container to create shared network on start up 2026-04-25 15:03:07 +00:00
MEMORY.md memory 2026-04-02 10:24:31 +00:00
package-lock.json restructuring openUrpn code 2023-07-20 11:41:43 +01:00
package.json restructuring openUrpn code 2023-07-20 11:41:43 +01:00
pyproject.toml slice 14a: ml_training_data pkg + sample.py (CSV filter + random sample) 2026-05-16 17:39:43 +00:00
pyrightconfig.json slice 14d: build_features wires bulk reader -> mapper -> EpcMlTransform 2026-05-16 18:38:41 +00:00
pytest.ini tests files 2026-06-04 11:47:42 +00:00
README.md adding to dev container to create shared network on start up 2026-04-25 15:03:07 +00:00
run_lambda_local.sh debugging local lambda run and updating the sap point checking condition 2023-09-13 18:47:12 +01:00
serverless.yml added logic to add to serverless 2026-04-22 12:39:44 +00:00
test.requirements.txt tests wrong environemnt 2026-05-29 16:17:06 +00:00
tox.ini removing playright install for integration test 2026-04-30 20:08:13 +00:00
UBIQUITOUS_LANGUAGE.md standardist Address 2026-06-01 16:32:48 +00:00

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