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apps:biomet_pmv [2014/09/15 13:40] – enviadminapps:biomet_pmv [2014/09/15 13:42] – enviadmin
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 ==== Extention to outdoor conditions ==== ==== Extention to outdoor conditions ====
  
-As mentioned above, the concept of PMV/PPD as established by Fanger (1972) was designed for indoor applications. This did affect two fundamental aspects of the PMV mode: the design of the equations and the transition from energy balance units to comfort votes.+As mentioned above, the concept of PMV/PPD as established by Fanger (1972) was designed for indoor applications. This does affect two fundamental aspects of the PMV mode: the design of the equations and the transition from energy balance units to comfort votes.
    
 First, using the clothing surface temperature as the only environment sensitive variable may be acceptable under office conditions in the absence of direct sun light and almost no ventilation. In an outdoor setting in warm to hot climates, relevant fractions of the human body are not covered by clothing but are exposed to the outdoor envionment with varing radiative loads and higher wind speeds. For those parts of the body, the skin temperature will be substantially different to the values estimated by the equations above.  First, using the clothing surface temperature as the only environment sensitive variable may be acceptable under office conditions in the absence of direct sun light and almost no ventilation. In an outdoor setting in warm to hot climates, relevant fractions of the human body are not covered by clothing but are exposed to the outdoor envionment with varing radiative loads and higher wind speeds. For those parts of the body, the skin temperature will be substantially different to the values estimated by the equations above. 
  
-Secondly, the PMV equation relates physical values (energy balance) to a personal comfort assessement. This has been achieved through tests using  volunteering persons in a climate camber. As a matter of fact and humanity, the PMV range was only checked within the range of -4 to +4, so the volunteeres were neither deep frozen nor grilled. From a schentific point of view, the transition from an energy balance to a comfort vote based on an an empirical study is only valid withing the range of the original study. Applying the PMV equation to outdoor conditions in summer heat stress situations can easily produce PMV values high above +4 (+8 and more). While this result is numerically correct, it violates the range of the original PMV system.+Secondly, the PMV equation relates physical values (energy balance) to a personal comfort assessement. This has been achieved through tests using  volunteering persons in a climate camber. As a matter of fact and humanity, the PMV range was only checked within the range of -4 to +4, so the volunteeres were neither deep frozen nor grilled. From a scientific point of view, the transition from an energy balance to a comfort vote based on an an empirical study is only valid within the range of the original study. Applying the PMV equation to outdoor conditions in summer heat stress situations can easily produce PMV values high above +4 (+8 and more). While this result is numerically correct, it violates the range of the original PMV system.
  
 Despite these problems, PMV in its outdoor version is able summarize the effects of air temperature, radiation, humidity and wind on the persons energy balance in one value each of it weighted with level of influence.  Despite these problems, PMV in its outdoor version is able summarize the effects of air temperature, radiation, humidity and wind on the persons energy balance in one value each of it weighted with level of influence.