Mitsubishi Electric Lossnay LGH-F1200RX5-E, Technical Manual

Page: 21 / 105

U-12
CHAPTER 1
•
Ventilation for Healthy Living
•
Determining Internal Heat Gain
When classifying loads, the internal heat gain (indoor generated heat + indoor penetration heat) is the ventilation air load
subtracted from the approximate cooling load when it is assumed that there is no reheating load.
(Internal heat gain)
= 14.6 W/ft
2
(157.0 W/m
2
) – 4.9 W/ft
2
(53.0 W/m
2
) = 9.7 W/ft
2
(104.0 W/m
2
)
•
The value of internal heat gain is based on assumptions for typical loads. To determine individual levels of internal heat gain,
the following is suggested:
•
Indoor Generated Heat
(1) Heat generated from occupants
Heat generation design value per person (occupant) in the office:
Sensible heat (SH) = 63.0 W/person (W·occupant)
Latent heat (LH)
= 69.0 W/person (W·occupant)
Total heat (TH) = 132.0 W/person (W·occupant)
The heat generated per 1 ft
2
(m
2
) of floor space:
Heat generated from occupants = 132.0 W/person (132.0 W·occupant) × 0.0186 person/ft
2
(0.2 occupant/m
2
) = 2.5W/ft
2
(26.4 W/m
2
)
(2) Heat generated from electrical equipment (lighting)
The approximate value of the lighting and power required for a general office with lighting of 300 - 350 Lux, is 1.9 - 2.8 W/ft
2
(20 - 30 W/m
2
).
Heat generated from electrical equipment (lighting) = 30 W/m
2
•
Indoor Penetration Heat
The heat that penetrates into the building from outside, which can be determined by subtracting the amount of heat generated
by occupants and lighting from the internal heat gain.
(Indoor infiltration heat)
= 9.7 - (2.5 + 2.8) = 4.4 W/ft
2
(104.0 – (26.4 + 30.0) = 47.6 W/m
2
)