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'''Operative temperature''' (<math>t_o</math>) is defined as a uniform temperature of
▲'''Operative temperature''' (<math>t_o</math>) is defined as a uniform temperature of a radiantly black enclosure in which an occupant would exchange the same amount of heat by [[radiation]] plus [[convection]] as in the actual nonuniform environment.<ref>ASHRAE Terminology, ASHRAE Handbook CD, 1999-2002</ref> Some references also use the terms 'equivalent temperature" or 'effective temperature' to describe combined effects of convective and radiant heat transfer.<ref>Nilsson, H.O., Comfort Climate Evaluation with Thermal Manikin Methods and Computer Simulation Models, National Institute for Working Life, 2004, pg. 37</ref> In design, operative temperature can be defined as the average of the [[Mean radiant temperature|mean radiant]] and [[Dry-bulb temperature|ambient air temperatures]], weighted by their respective [[heat transfer coefficient|heat transfer coefficients]].<ref>Thermal Comfort, ASHRAE Handbook, Fundamentals, Ch. 9, pg.3, 2009</ref> The instrument used for assessing environmental thermal comfort in terms of operative temperature is called a eupatheoscope and was invented by A. F. Dufton in 1929.<ref>Glossary of Meteorology, American Meteorological Society, < http://amsglossary.allenpress.com/glossary/browse?s=e&p=42>, accessed Sept 2010</ref> Mathematically, operative temperature can be shown as;
::<big><math>t_o = \frac{(h_r t_{mr} + h_c t_a)}{ h_r + h_c}</math></big>
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:<math>t_a</math> = air temperature
:<math>t_{mr}</math> = mean radiant temperature
Or
::<big><math>t_o = \frac{(t_{mr} + (t_a \times \sqrt{10v}))}{ 1 + \sqrt{10v}}</math></big><ref>{{Cite journal | author = International Standard Organization | year = 1998 | title = ISO 7726:1998 Ergonomics of the thermal environment -- Instruments for measuring physical quantities}}</ref>
where,
:<math>v</math> = air velocity
:<math>t_a</math> and <math>t_{mr}</math> have the same meaning as above.
It is also acceptable to approximate this relationship for occupants engaged in near sedentary physical activity (with metabolic rates between 1.0 met and 1.3 met), not in direct sunlight, and not exposed to air velocities greater than 0.10 m/s (20 fpm). <ref>ANSI/ASHRAE Standard 55-2010, Thermal Environmental Conditions for Human Occupancy</ref>
::<big><math>t_o = \frac{(t_a + t_{mr})}{ 2 }</math></big>
where <math>t_a</math> and <math>t_{mr}</math> have the same meaning as above.
==Application==
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==References==
{{Reflist}}
{{DEFAULTSORT:Operative Temperature}}
[[Category:Heating,
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