Methodology, sources and limitations

Calculation principle

SetMyTemp uses a simplified implementation of the Fanger PMV thermal-comfort model, associated with ISO 7730. It looks for an air temperature targeting a near-neutral sensation, then rounds the displayed setting.

Sensitivity profiles shift the target to represent a colder or warmer preference. They are not an individual physiological measurement.

Input data

• Current weather: outdoor temperature, relative humidity, wind, radiation and recent conditions supplied by Open-Meteo.
• Dwelling: apartment or house, insulation level and floor area, used for simple estimates of surface exposure and air exchange.
• Occupant: quiet activity, standard clothing and a sensitivity profile.
• Optional measurements: indoor temperature and humidity or outdoor readings entered by the user, replacing some estimates.

Surface temperature and perceived comfort

Wall and window temperatures are not measured inside the dwelling. They are estimated from outdoor conditions and the declared characteristics. The model combines this estimate with air, humidity and air movement so that comfort is not reduced to the thermostat reading alone.

References and sources

• ISO 7730 — analytical determination and interpretation of thermal comfort using PMV and PPD indices.
• EN 16798-1, category II — a comfort reference for normal expectations in buildings.
• ISO 8996 — the metabolic-rate reference.
• ADEME — practical temperature and heating-saving guidance, in French.
• Open-Meteo — live weather data.

City-page climate data

Climate tables show 2016–2025 averages from ERA5, a Copernicus reanalysis product, distributed through the Open-Meteo historical API. Temperatures are corrected for the altitude difference between the city and the model grid cell.

These averages describe past climate. They predict neither today’s weather nor a future event. Heating-season, frost-day and hot-day counts are summary indicators, not equipment-setting instructions.

Sources: Copernicus and the Open-Meteo historical API documentation.

Limitations to understand

• Supplied weather may differ from actual conditions at your address.
• Geometry, thermal mass, air leakage and actual surface temperatures are simplified.
• The model knows neither the equipment condition, its capacity nor the dwelling’s actual controls.
• It does not account for medical needs or particular occupant circumstances.
• The result is not a thermal study, a diagnosis or a guarantee of savings.

The result is setting guidance. Your indoor measurement, your own comfort and applicable professional advice take priority.