Local Thermal comfort

Local thermal comfort criteria
Draught risk (DR)
Depending on air temperature, air velocity, turbulence and activity the DR percentage indicates the complaints of uncomfortable draughts by the room users. This sets the maximum allowable air velocities that should be implemented by ventilation technicians.

Vertical room temperature gradient

Limiting large differences in the local convective heat flux densities between the head (seated humans
1.1 m above the floor) and feet (0.1 m height) by establishing a maximum allowable air temperature difference i.e. The vertical temperature gradient. This criteria should be tested particularly where large vertical temperature differences are expected e.g.air heating, convector heating, section all radiators on internal walls.

Maximum radiation asymmetry
Limiting large differences in distribution of radiated heat. This occurs when there are individual anomalies in surface temperatures just below the average environmental temperature e.g.with large external walls.