The room sensible heat factor (RSHF) represents the psychrometric process of the supply air within the conditioned space. Room Sensible Heat Factor is the ratio of room sensible and room latent heat.

RSHF = room sensible heat factor

RSH = room sensible heat

RLH = room latent heat

RTH = room total heat

The supply air to a conditioned space must have the capacity to offset simultaneously both the room sensible and room latent heat loads. The process is plotted on the standard psychrometric chart as below.

The slope of the RSHF line illustrates the ratio of sensible to latent loads within the space. RSH is projected on the enthalpy lines to estimate the ∆hs (sensible load) and RLH is projected on the enthalpy lines to estimate the ∆hl (latent load). Room total load (RTH) is the enthalpy difference between the room design condition and the supply air condition.

Thus, if adequate air is supplied to offset these room loads, the room requirements will be satisfied, provided both the dry- and wet-bulb temperatures of the supply air fall on this line.

The figure above also shows a third point, defined as the apparatus dew point (ADP). The ADP represents an effective coil surface condition and the apparatus dew point temperature can loosely be thought of as the coil temperature. The ADP is determined by extending the straight line between the entering and leaving air states until it reaches the saturation curve.