Space cooling load due to the heat gain
from electric lights is often the major component for commercial buildings having a larger
ratio of interior zone. Electric lights contribute to sensible load only. Sensible heat
released from electric lights is in two forms:

(i) convective heat from the lamp, tube and
fixtures.

(ii) radiation absorbed by walls, floors,
and furniture and convected by the ambient air after a time lag.

The sensible heat released (Qles) from
electric lights is calculated as:

(12)

where Input = total light wattage obtained
from the ratings of all fixtures installed

Fuse = use factor defined as the ratio of
wattage in use possibly at design condition to the installation condition

Fal = special allowance factor for
fluorescent fixtures accounting for ballast loss, varying from 1.18 to 1.30

The corresponding sensible space cooling
load (Qls) due to heat released from electrical light is:

(13)

CLF is a function of

(i) number of hours that electric lights
are switched on (for 24 hours continuous lighting, CLF = 1), and

(ii) types of building construction and
furnishings.

Therefore, CLF depends on the magnitude of
surface and the space air flow rates.

**4.3.2.2 People**

Human beings release both sensible heat and
latent heat to the conditioned space when they stay in it. The space sensible (Qps) and
latent (Qpl) cooling loads for people staying in a conditioned space are calculated as:

(14)

(15)

where n = number of people in the
conditioned space

SHG = sensible heat gain per person (Table
8)

LHG = latent heat gain per person (Table 8)

Adjusted values for total heat shown in
Table 8 is for normal percentage of men, women and children of which heat released from
adult female is 85% of adult male, and that from child is 75%.

CLF for people is a function of

(i) the time people spending in the
conditioned space, and

(ii) the time elapsed since first entering.