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Tri-sensor Calculation and Remote Cable
Heat Index/Humidex
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Heat Index/Humidex
The Heat Index is determined using the dry bulb temperature and relative humidity.
Based upon charts available from the U.S. National Weather Service, Heat Index
represents how an average person feels relative to climate conditions. For a given
temperature, the higher the humidity, the higher the heat index.
The Heat Index is defined over a temperature range of 70°F - 120°F (21°C - 49°C) and
a relative humidity range of 30% - 99%. Outside of this range, the instrument will show
dashes in the display for the Heat Index.
The Humidex, used primarily in Canada, functions similar to the Heat Index concept.
The values are slightly different. The Humidex is defined over a temperature range of
70°F - 109°F (21°C - 43°C) and a relative humidity range of 20% - 99%. Outside of
this range, the instrument will show dashes in the display for the Humidex.
Air Flow
The QUESTemp° 36 measures air flow if the Air Probe accessory is used. The Air
Probe uses an omni-directional anemometer sensor that measures air flow
between 0 and 20 meters per second in 0.1m/s increments. Please see “Air Flow
Functionality”, page 16 for more details.
Thermal Comfort (QUESTempº 36 model only)
Thermal comfort readings for indoor environments are a benefit of DMS software
and are not displayed or printed from the instrument directly. Readings are derived
from the dry bulb, relative humidity, mean radiant temperature, air flow, and user
entered parameters of clothing, metabolic rate and external work.
Thermal comfort indices, Predicted Mean Vote (PMV) and Predicted Percent
Dissatisfied (PPD), help predict the thermal satisfaction level of a person with their
indoor environment. The PMV is a rating scale of +3 to -3 where +3 is much to warm,
-3 is much too cool, and 0 is thermally neutral. The PPD reflects what percent of
people in a given location would be dissatisfied with their thermal surroundings.
The formulas used by DMS software to derive the PMV and PPD come from the
international standard ISO 7730 “Moderate thermal environments - Determination of
the PMV and PPD indices and specification of the conditions for thermal comfort”.