comfortkit 0.4.0

Thermal comfort prediction API — PMV, adaptive ASHRAE 55, EN 16798 — with uncertainty bounds and a deployable REST endpoint

comfortkit

A Python library and REST API for thermal comfort prediction with uncertainty bounds and personalised comfort learning. Wraps pythermalcomfort as the computational backend and adds what it doesn't have: a deployable REST endpoint, bootstrap and conformal confidence intervals on every prediction, an ML correction layer trained on real occupant votes, and a per-user Bayesian model that adapts from feedback. For interactive, point-and-click comfort analysis the CBE Thermal Comfort Tool remains the reference — comfortkit is its programmatic complement, built for automated pipelines, sensor integrations, and applications that need to call predictions at scale.

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Quick start

pip install comfortkit

from comfortkit import predict

result = predict(
    model="pmv",
    ta=22.0,   # air temperature, °C
    tr=22.0,   # mean radiant temperature, °C
    vel=0.1,   # air velocity, m/s
    rh=60.0,   # relative humidity, %
    met=1.2,   # metabolic rate, met
    clo=0.5,   # clothing insulation, clo
)

print(result.pmv)        # -0.75
print(result.ppd)        # 16.9
print(result.sensation)  # "slightly cool"
print(result.ci_95)      # e.g. (-1.4, -0.2)  — varies; bootstrap CI is stochastic
print(result.compliant)  # False
print(result.warnings)   # []

The ci_95 field is a bootstrap confidence interval on PMV — accounting for typical sensor measurement uncertainty (±0.5°C air temp, ±2°C radiant temp, ±5% RH, ±0.05 m/s velocity). Pass your own sigma values via predict(..., sigma={...}) to match your actual sensor spec.

---

REST API

docker compose up

curl -X POST http://localhost:8000/v1/predict \
  -H "Content-Type: application/json" \
  -d '{
    "model": "pmv",
    "ta": 22.0,
    "tr": 22.0,
    "vel": 0.1,
    "rh": 60.0,
    "met": 1.2,
    "clo": 0.5
  }'

{
  "pmv": -0.75,
  "ppd": 16.9,
  "sensation": "slightly cool",
  "compliant": false,
  "model": "standard_pmv",
  "ci_95": [-1.47, -0.22],
  "warnings": []
}

Interactive API docs at http://localhost:8000/docs (OpenAPI, auto-generated).

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Why comfortkit?

pythermalcomfort is the best open implementation of thermal comfort physics. comfortkit does not replace it — it builds on top of it:

Feature	pythermalcomfort	comfortkit
PMV/PPD, adaptive, UTCI, SET	Yes	Via adapter
Uncertainty / confidence intervals	No	Yes — bootstrap CI (sensor noise) + conformal CI (data-grounded, 95.3% empirical coverage)
REST API + Docker	No	Yes — FastAPI, OpenAPI docs
Pydantic v2 typed interface	No	Yes
Applicability warnings (non-fatal)	Raises / returns nan	Structured warnings list
Batch predictions	Yes	Yes
ML correction layer	No	Yes (v0.2) — LightGBM residual model, ONNX
Personalised comfort	No	Yes (v0.3) — per-user Bayesian update from occupant votes

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Supported standards

Standard	Model key	Notes
ISO 7730	pmv / standard="iso"	PMV/PPD via pmv_ppd_iso
ASHRAE 55	pmv / standard="ashrae"	PMV/PPD via pmv_ppd_ashrae
ASHRAE 55 SET	set	Standard Effective Temperature; result in set_tmp
ASHRAE 55 adaptive	adaptive_ashrae (alias adaptive)	Requires t_running_mean; includes CE fix (see below)
EN 16798-1	Coming v1.0	Adaptive model

A note on numerical differences with the CBE Thermal Comfort Tool. The CBE Thermal Comfort Tool pins pythermalcomfort==2.10, while comfortkit targets pythermalcomfort>=3.9. Small PMV differences — typically less than 0.1 — are therefore expected for the same inputs. Neither result is wrong; they reflect different versions of the same underlying library. If you need comfortkit's output to match the CBE tool exactly for validation purposes, install pythermalcomfort==2.10 in an isolated environment and compare directly against that version.

A note on ISO vs ASHRAE divergence. The two standards produce different PMV values for the same inputs whenever air velocity is non-negligible, because they apply different relative air velocity adjustments before computing the convective heat loss term. For example, ISO 7730 Annex D case C (ta=27, tr=27, vel=0.3) yields PMV = +0.43 under ISO and PMV = +0.23 under ASHRAE — a difference of 0.20 PMV units. This is expected behaviour, not a bug. comfortkit faithfully reproduces pythermalcomfort's implementation of both standards; if you see this divergence, pass standard="iso" or standard="ashrae" explicitly to make the intended calculation clear.

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Uncertainty quantification

Every PMV prediction carries two complementary confidence intervals:

Bootstrap CI (ci_95) — parametric bootstrap over sensor measurement noise. Reflects how much PMV would shift if your sensors were reading slightly off. Width is typically ±0.5–0.8 PMV units under standard sensor tolerances.

Conformal CI (conformal_ci_95) — split conformal prediction interval calibrated on real occupant TSV votes from the ASHRAE Global Thermal Comfort Database II. Answers the question "how far might the actual occupant vote deviate from the PMV prediction?" — a harder, more honest uncertainty bound. Half-width q=2.77, empirical test-set coverage 95.3%.

result = predict(model="pmv", ta=22.0, tr=22.0, vel=0.1, rh=60.0, met=1.2, clo=0.5)

print(result.ci_95)           # e.g. (-1.4, -0.2)  — sensor-noise bootstrap
print(result.conformal_ci_95) # e.g. (-3.5, 1.8)   — data-grounded, TSV vs PMV

For custom sensor uncertainty, use monte_carlo_propagate directly:

from comfortkit.uncertainty import monte_carlo_propagate
from comfortkit.models.base import ComfortInputs

inputs = ComfortInputs(ta=24, tr=25, vel=0.1, rh=50, met=1.2, clo=0.7)

ci = monte_carlo_propagate(
    inputs,
    sigma={"ta": 0.3, "tr": 1.0, "vel": 0.02, "rh": 3.0},
    n_samples=5000,
)
print(ci)  # (lower_pmv, upper_pmv)

---

ML correction layer

model="ml" applies a LightGBM residual correction on top of standard PMV, trained on the ASHRAE Global Thermal Comfort Database II (~78 k field observations across 41 studies; Földváry Ličina et al., 2018). The model predicts the (TSV − PMV) residual and adds it back to the physics estimate.

from comfortkit import predict

result = predict(
    model="ml",
    ta=22.0,
    tr=22.0,
    vel=0.1,
    rh=60.0,
    met=1.2,
    clo=0.5,
    # optional — improve accuracy when available
    t_out=8.0,                         # outdoor monthly mean temp (°C)
    cooling_strategy="Naturally Ventilated",
    building_type="Office",
)

print(result.pmv)     # -0.62
print(result.ppd)     # 13.7
print(result.model)   # "ml_pmv"
print(result.ci_95)   # (-1.34, -0.10)

The three optional fields — t_out, cooling_strategy, building_type — capture adaptive-comfort effects that the standard PMV formula ignores. They are optional: if omitted, the model falls back to dataset medians / unknown-category encodings. The correction is served via ONNX Runtime with no LightGBM dependency at inference time.

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Personalised comfort (v0.3)

POST /v1/feedback accepts an occupant thermal preference vote and updates a per-user Beta-Bernoulli posterior (Dirichlet-Multinomial, K=2) warm-started from the aggregate prior. GET /v1/comfort/{user_id} returns the current personalised prediction.

# Submit a vote: this occupant wants it Cooler
curl -X POST http://localhost:8000/v1/feedback \
  -H "Content-Type: application/json" \
  -d '{
    "user_id": "desk-42",
    "vote": 1,
    "heart_rate": 74.0,
    "t_net": 27.5,
    "rh_net": 65.0,
    "clothing": "Light",
    "met": "sitting"
  }'

{
  "user_id": "desk-42",
  "n_votes": 1,
  "p_cooler": 0.4907,
  "prediction": 0,
  "prediction_label": "Not Cooler"
}

# Retrieve the personalised prediction after enough votes have accumulated
curl http://localhost:8000/v1/comfort/desk-42

{
  "user_id": "desk-42",
  "p_cooler": 0.8731,
  "prediction": 1,
  "prediction_label": "Cooler",
  "n_votes": 47,
  "confidence": "medium"
}

The prior is weak (5 pseudo-counts from the Dorn study aggregate). Roughly 10–20 votes are enough to pull the posterior away from the global mean; by 50 votes, users with atypical preferences are predicted correctly >90% of the time. Contextual features (heart_rate, t_net, rh_net, clothing, met) are stored in the audit log for future feature-conditioned extensions.

Vote data is stored in SQLite by default (COMFORTKIT_DB env var to override). See CONTRIBUTING.md for the Postgres migration path before production deployment.

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Roadmap

Version	Scope
v0.1	PMV adapter + bootstrap CI + FastAPI REST + PyPI ✓
v0.2	ML correction layer trained on ASHRAE Global Thermal Comfort DB II + ONNX export ✓
v0.2.1	SET adapter + adaptive ASHRAE 55 adapter + CE bug fix (pythermalcomfort 3.9.2) ✓
v0.2.2	Conformal prediction CI calibrated on real TSV votes; q=2.77, 95.3% coverage ✓
v0.3	Personalised comfort — Bayesian update from occupant votes via /v1/feedback ✓
v1.0	Stable API contract, full docs site, Zenodo DOI

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Contributing

See CONTRIBUTING.md. Good first issues are labelled good-first-issue.

We especially welcome: additional model adapters (EN 16798 adaptive, UTCI), BMS/sensor platform integrations, and occupant comfort survey datasets for the v0.2 ML layer.

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Citation

If you use comfortkit in research, please cite:

@software{comfortkit,
  author  = {Kottapalli, Kalyan},
  title   = {comfortkit: Thermal comfort prediction with uncertainty bounds and REST API},
  year    = {2026},
  url     = {https://github.com/K2alyan/comfortkit},
}

A Zenodo DOI will be registered at v1.0.

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Acknowledgements

comfortkit uses pythermalcomfort as its computational backend. If comfortkit is useful to you, consider starring that project too.

The v0.2 ML correction layer was trained on the ASHRAE Global Thermal Comfort Database II. If you use model="ml" in your work, please cite the original data paper:

Földváry Ličina, V., Cheung, T., Zhang, H., de Dear, R., Parkinson, T., Arens, E., & Schiavon, S. (2018). Development of the ASHRAE Global Thermal Comfort Database II. Building and Environment, 142, 502–512. https://doi.org/10.1016/j.buildenv.2018.06.022

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License

MIT © Kalyan Kottapalli