The therm (symbol, thm) is a non-SIunit of heatenergy equal to 100,000 British thermal units (Btu^[1]). It is approximately the energy equivalent of burning 100 cubic feet (2.83 cubic metres) – often referred to as 1 CCF – of natural gas.

End user license agreement software: therm version: 7. Important - read carefully: this end user license agreement ('agreement') is a legal agreement between you (in your capacity as an individual and as an agent for your company, institution or other entity) (collectively, 'you' or 'licensee') and the regents of the university of california, department of energy contract-operators of the. Psi Therm 2D & 3D provides the user with an accessible and easy-to-use interface to construct detailed building sections to determine heat flows & surface temperatures. The software automatically calculates psi-values & fRsi values, and generates comprehensive reports in accordance with the relevant standards & conventions for. Therm takes care of the time-consuming calculation of the required cooling output and selects suitable products. Once the calculation is complete, you will receive detailed documentation. This provides maximum peace of mind when designing the optimum climate control. Therm is based on the requirements of IEC/TR3 60890 890 AMD 1 and DIN 3168 for.

Since natural gas meters measure volume and not energy content, a therm factor is used by natural gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. The therm factor is usually expressed in units of therms per CCF. It will vary with the mix of hydrocarbons in the natural gas. Natural gas with a higher than average concentration of ethane, propane or butane will have a higher therm factor. Impurities, such as carbon dioxide or nitrogen, lower the therm factor.

The volume of the gas is calculated as if measured at standard temperature and pressure (STP).

One therm is equal to about 105.5megajoules, 25200kilocalories, or 29.3kilowatt-hours.

The therm sometimes has been confused with the thermie. The names of both units come from the Greek word for heat.

Definitions[edit]

• Therm (EC) ≡ 100000BTU_ISO^[2]

  = 105506000joules

  ≈ 29.3072kWh

  The therm (EC) is often used by engineers in the US.

• Therm (US) ≡ 100000BTU_59°F^[3]

  = 105480400joules

  ≈ 29.3001111111111kWh.

• Therm (UK) ≡ 105505585.257348joules^[4]

  ≡ 29.3071070159300kWh

10 therms are known as a decatherm (sometimes, dekatherm;^[5] commonly abbreviated Dth), which is 1000000Btu (of whichever type). Further common abbreviations are MDth for a 1000 decatherms, and MMDth for 1000000 decatherms.^{[5][failed verification]}

Usage[edit]

United Kingdom regulations were amended to replace therms with joules with effect from 1999, with natural gas usually retailed in the derived unit, kilowatt-hours. Despite this, the wholesale UK gas market trades in therms. In the United States, natural gas is commonly billed in CCFs (hundreds of cubic feet) or therms.

Carbon footprint[edit]

According to the EPA burning one therm of natural gas produces on average 5.3 kg (11.7 lb) of carbon dioxide.^[6]

See also[edit]

Therm Software Manual

References[edit]

1. ^IEEE Std 260.1-2004
2. ^Official Journal L 073, P. 0114 27 March 1972
3. ^15 USC Chapter 6Archived 2006-01-25 at the Wayback Machine
4. ^The Units of Measurement Regulations 1995
5. ^ ^abJerry Knight (22 January 1978). 'Gas Utilities Stepping Up Efforts to Add Customers'. The Washington Post. Retrieved 1 June 2016.
6. ^epa.gov 'Greenhouse Gases Equivalencies Calculator - Calculations and References

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