# Temperature and Relative Humidty Measurements ## Reference levels Temperature and humidity have a big impact on **comfort and health**, and on how other pollutants behave (mould, dust mites, or the emission of VOCs from materials increase with temperature and humidity). The values below refer to **indoor** environments. Outdoors, what is _good_ or _bad_ depends a lot on the local climate, and heat warnings are generally based on local thresholds. | Parameter | Reference | Value | |:- |:- |:- | | Temperature | WHO Housing and Health Guidelines [^1] | At least **18 ºC** indoors during the cold season (higher for older people, children and people with chronic illness) | | Temperature | EN 16798-1, category II, offices and homes [^2] | **20 – 24 ºC** in winter (heating), **23 – 26 ºC** in summer (cooling) | | Relative humidity | EN 16798-1, design values [^2] | **25 – 60 %rh** (category II), **30 – 50 %rh** (category I) | As a general orientation for relative humidity indoors: | Relative humidity | Interpretation | |:-: |:- | | < 30 % | Too dry: irritation of eyes and airways, static electricity | | 30 – 60 % | Comfortable range | | > 60 % | Too humid: higher risk of mould and dust mites, specially if it stays high for long periods or there is condensation on walls and windows | !!! info "Sensor placement" The heat of the electronics can make the readings of the kit's internal sensors higher than the real air temperature (and the humidity lower). Check the [SHT3X page](https://docs.smartcitizen.me/knowledge/air/temperature_rel_humidity/Sensirion_SHT3X.md) for the default offsets and how to correct them before comparing the readings with these values. ## Supported Sensors There are plenty of different temperature (and relative humidity sensors). In general, these do not necessarily go together, but many manufacturers have combined them in digital sensors. - [Dallas DS18B20](https://docs.smartcitizen.me/knowledge/air/temperature_rel_humidity/DS18B20.md) (Field | air; Metric | temperature; Connection | external): One-wire weather-proof temperature sensor. - [Sensirion SHT3X Weatherproof](https://docs.smartcitizen.me/knowledge/air/temperature_rel_humidity/Sensirion_SHT3X-weatherproof.md) (Field | air; Metric | temperature; Connection | external): A temperature and humidity sensor in a weatherproof capsule - [Sensirion SHT3X](https://docs.smartcitizen.me/knowledge/air/temperature_rel_humidity/Sensirion_SHT3X.md) (Field | air; Metric | temperature; Connection | onboard): A temperature and humidity sensor that we love! Available in SCK2.X. ## References [^1]: World Health Organization. “WHO Housing and Health Guidelines.” Geneva: World Health Organization, 2018. https://www.who.int/publications/i/item/9789241550376. [^2]: CEN. “EN 16798-1:2019 Energy performance of buildings - Ventilation for buildings - Part 1: Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics.” 2019.