Mercury-in-glass thermometer measuring an ambient temperature of 23 °C (73 °F) a little above the room temperature range

Room temperature, colloquially, denotes the range of air temperatures most people find comfortable indoors while dressed in typical clothing. These temperatures feel comfortable to people wearing typical indoor clothing. But comfortable temperatures can be extended beyond this range depending on humidity, air circulation, and other factors.

In certain fields, like science and engineering, and within a particular context, room temperature can mean different agreed-upon ranges. In contrast, ambient temperature is the actual temperature, as measured by a thermometer, of the air (or other medium and surroundings) in any particular place. The ambient temperature (e.g. an unheated room in winter) may be very different from an ideal room temperature.

Food or beverages may be served at "room temperature", meaning neither heated nor cooled.

Comfort temperatures

Main article: Thermal comfort

The American Heritage Dictionary of the English Language identifies room temperature as around 20–22 °C (68–72 °F),[1] while the Oxford English Dictionary states that it is "conventionally taken as about 20 °C (68 °F)".[2]

Ideal room temperature varies vastly depending on the surrounding climate. Studies from Indonesia have shown that the range of comfortable temperature falls between 24–29 °C (75–84 °F) for local residents.[3] Studies from Nigeria show a comfortable temperature range of 26–28 °C (79–82 °F), comfortably cool 24–26 °C (75–79 °F) and comfortably warm 28–30 °C (82–86 °F).[4] A field study conducted in Hyderabad, India returned a comfort band of 26–32.45 °C (79–90 °F) with a mean of 29.23 °C (85 °F).[5] A study conducted in Jaipur, India among healthy young men showed that the neutral thermal comfort temperature was analyzed to be 30.15 °C (86 °F), although a range of 25.9–33.8 °C (79–93 °F) was found.[6]

Owing to variations in humidity and (likely) clothing, recommendations for summer and winter may vary; a suggested typical range for summer is 23–25.5 °C (73–78 °F), with that for winter being 20–23.5 °C (68–74 °F).[7] Some studies have suggested that thermal comfort preferences of men and women may differ significantly, with women on average preferring higher ambient temperatures.[8][9][10]

In the recent past it was common for house temperatures to be kept below the comfort level; a 1978 UK study found average indoor home temperatures to be 15.8 °C (60.4 °F) while Japan in 1980 had median home temperatures of 13 °C (55 °F) to 15 °C (59 °F).[11]

Rooms may be maintained at an ambient temperature above the comfort temperature in hot weather, or below it in cold weather, if required by cost considerations or practical issues (e.g. lack of air conditioning or relatively high expense of heating.)

In the UK, the Offices, Shops and Railway Premises Act 1963 provides for a minimum temperature in commercial premises, but not for a maximum temperature.

Health effects

See also: Sick building syndrome

A digital thermometer reading an ambient temperature of 36.4°C (97°F) in an unventilated room during a heat wave; a high indoor temperature can cause heat exhaustion or heat stroke in a person.

The World Health Organization in 1987 found that comfortable indoor temperatures of between 18 and 24 °C (64 and 75 °F) were not associated with health risks for healthy adults with appropriate clothing, humidity, and other factors. For infants, elderly, and those with significant health problems, a minimum 20 °C (68 °F) was recommended. Temperatures lower than 16 °C (61 °F) with humidity above 65% were associated with respiratory hazards including allergies.[12][13]

The WHO's 2018 guidelines give a strong recommendation that a minimum of 18 °C (64 °F) is a "safe and well-balanced indoor temperature to protect the health of general populations during cold seasons". A higher minimum temperature may be necessary for vulnerable groups including children, the elderly, and people with cardiorespiratory disease and other chronic illnesses. However, the recommendation regarding risk of exposure to high indoor temperatures is only "conditional". Minimal-risk high temperatures range from about 21 to 30 °C (70 to 86 °F) depending on the region, with maximum acceptable temperatures between 25 and 32 °C (77 and 90 °F).[14][15]

Definitions in science and industry

Temperature ranges are defined as room temperature for certain products and processes in industry, science, standards, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines controlled room temperature as between 20 and 25 °C (68 and 77 °F), with excursions between 15 and 30 °C (59 and 86 °F) allowed, provided the mean kinetic temperature does not exceed 25 °C (77 °F).[16] The European Pharmacopoeia defines it as being simply 15 to 25 °C (59 to 77 °F), and the Japanese Pharmacopeia defines "ordinary temperature" as 15 to 25 °C (59 to 77 °F), with room temperature being 1 to 30 °C (34 to 86 °F).[17][18] Merriam-Webster gives as a medical definition a range of 15 to 25 °C (59 to 77 °F) as being suitable for human occupancy, and at which laboratory experiments are usually performed.[19]

See also


  1. ^ The American Heritage Dictionary of the English Language (5th ed.). 2014. Archived from the original on 2015-01-08.
  2. ^ Oxford English Dictionary, Third Edition, November 2010), sub-entry at room.
  3. ^ Karyono, Tri Harso (21 July 2015). "Predicting Comfort Temperature in Indonesia, an Initial Step to Reduce Cooling Energy Consumption". Buildings. 5 (3). School of Architecture, Tanri Abeng University, Jalan Swadarma Raya No 58, Pesanggarahan, Jakarta 12250, Indonesia: 802–813. doi:10.3390/buildings5030802.
  4. ^ Komolafe, L. Kayode; Akingbade, Folorunso O. A. (2003). "Analysis of thermal comfort in Lagos, Nigeria". Global Journal of Environmental Sciences. 2: 59–65. doi:10.4314/gjes.v2i1.2407. Retrieved 4 March 2021.
  5. ^ Indraganti, Madhavi (16 July 2009). "Using the adaptive model of thermal comfort for obtaining indoor neutral temperature: Findings from a field study in Hyderabad, India". Building and Environment. 45 (3): 519–536. doi:10.1016/j.buildenv.2009.07.006. Retrieved 10 August 2023 – via Elsevier Science Direct.
  6. ^ Dhaka, Shivraj (2014-12-13). "Assessment of thermal environmental conditions and quantification of thermal adaptation in naturally ventilated buildings in composite climate of India". Building and Environment. 66. Department of Mechanical Engineering, Malaviya National Institute of Technology Jaipur, India: 42–53. doi:10.1016/j.buildenv.2013.04.015. Archived from the original on 30 January 2022. Retrieved 10 August 2023.
  7. ^ Burroughs, H. E.; Hansen, Shirley (2011). Managing Indoor Air Quality. Fairmont Press. pp. 149–151. ISBN 9780881736618. Archived from the original on 20 September 2014. Retrieved 25 December 2014.
  8. ^ Beshir, MY; Ramsey, JD (March 1981). "Comparison between male and female subjective estimates of thermal effects and sensations". Applied Ergonomics. 12 (1): 29–33. doi:10.1016/0003-6870(81)90091-0. PMID 15676395.
  9. ^ Karjalainen, Sami (April 2007). "Gender differences in thermal comfort and use of thermostats in everyday thermal environments". Building and Environment. 42 (4): 1594–1603. doi:10.1016/j.buildenv.2006.01.009.
  10. ^ Kingma, Boris; van Marken Lichtenbelt, Wouter (August 2015). "Energy consumption in buildings and female thermal demand". Nature Climate Change. 5 (12): 1054–1056. Bibcode:2015NatCC...5.1054K. doi:10.1038/nclimate2741. S2CID 83899840.
  11. ^ Mavrogianni, A.; Johnson, F.; Ucci, M.; Marmot, A.; Wardle, J.; Oreszczyn, T.; Summerfield, A. (2021-06-02). "Historic Variations in Winter Indoor Domestic Temperatures and Potential Implications for Body Weight Gain". Indoor + Built Environment. 22 (2): 360–375. doi:10.1177/1420326X11425966. PMC 4456148. PMID 26321874.
  12. ^ World Health Organization. Environmental Health in Rural and Urban Development and Housing Unit. (1990). Indoor environment : health aspects of air quality, thermal environment, light and noise (PDF). p. 17.
  13. ^ Lane, Megan (2011-03-03). "BBC News Magazine: How warm is your home". BBC News. Archived from the original on 2017-12-31.
  14. ^ WHO 2018, p. 34: 4 Low indoor temperatures and insulation / 4.1 Guideline recommendations / ... For countries with temperate or colder climates, 18 °C has been proposed as a safe and ....
  15. ^ WHO 2018, p. 54: 5 High indoor temperatures / 5.4 Research recommendations / Table 5.2 Research recommendations: high indoor temp / Current state of the evidence / Few high-quality studies have assessed the direct effects of indoor temperature on health..
  16. ^ "General Chapter < 659> Packaging and Storage Requirements" (PDF). United States Pharmacopeia. 1 May 2017. Retrieved 2018-04-04.
  17. ^ "What are the regulatory Definitions for "Ambient", "Room Temperature" and "Cold Chain"?". ECA Academy. 2 March 2017. Retrieved 2018-04-04.
  18. ^ Shein-Chung Chow (2007). Statistical Design and Analysis of Stability Studies. Chapman & Hall/CRC Biostatistics Series. CRC Press. p. 7. ISBN 9781584889069. Retrieved 4 April 2018. Definition of Room Temperature: According to the United States Pharmacopeia National Forumlary [sic] (USP-NF), the definition of room temperature is between 15 and 30 °C in the United States. However, in the EU, the room temperature is defined as being 15 to 25 °C, while in Japan, it is defined being 1 to 30 °C.
  19. ^ Merriam Webster's Medical Dictionary. 2016. Archived from the original on 2010-04-10.