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For example, in the range of normal temperatures, air at 68 °F (20 °C) and 50% relative humidity will become saturated if cooled to 50 °F (10 °C), its dew point, and 41 °F (5 °C) air at 80% relative humidity warmed to 68 °F (20 °C) will have a relative humidity of only 29% and feel dry.
The recommended level of indoor humidity is in the range of 30–60% in air conditioned buildings, [34] [35] but new standards such as the adaptive model allow lower and higher humidity, depending on the other factors involved in thermal comfort. Recently, the effects of low relative humidity and high air velocity were tested on humans after ...
For humidity ratios above 0.012 kg H 2 O/kg dry air (0.012 lb H 2 O/lb dry air), or for metabolic rates up to 2.0 met, the analytical model must be used to determine thermal comfort sensation. Also based on the PMV model, this method uses tools such as the ASHRAE Thermal Comfort Tool or the online CBE Thermal Comfort Tool for ASHRAE 55 [ 2 ] to ...
Mixing systems generally supply air such that the supply air mixes with the room air so that the mixed air is at the room design temperature and humidity. In cooling mode, the cool supply air, typically around 55 °F (13 °C) (saturated) at design conditions, exits an outlet at high velocity.
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). [12]
Humidity occurs in indoor environments due to building related causes. Porous walls, rising damp, and leaks in the building are determinants for structural dampness due to elevated humidity levels. [4]: 185–187 The construction of the building can also lead to humidity and unwanted moisture in the indoor environment. [15]
Moisture management and humidity control may conflict with efforts to conserve energy. For example, moisture management and humidity control requires systems to be set to supply make-up air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions.
The building materials industry also manages the moisture barrier properties in architectural components to ensure the correct moisture levels in the internal spaces of buildings. Optoelectronic devices based on organic material, generally named OLEDs , need an encapsulation with low values of WVTR to guarantee the same performances over the ...