Term Test

Steps in Calculating the Roof Load

• Calculate roof area (A) from architectural plans

• Select CLTD Roof for time of interest, typically on an hourly basis

• Determine roof construction and overall heat transfer coefficient (U)

• Select roof no. from ASHRAE Table 31 or Text table 7-34 which is closest to matching actual roof construction.

• Corrections: Values on tables

Match the Following

• Internal and External

• Internal Load

• Outside Ventilation Air

• OUTDOOR DESIGN : WEATHER CONDITIONS

• Summer 22oC to 26oC DB

• Components of cooling Load

• Check for PAG-ASA weather conditions for

• Indoor Conditions

•   heat generated by occupants, equipment

• Components of Space Heat Gain

Which line Indicates the Dry bulb Temperature?

Which line represents a Wet bulb Temperature?

Which line represents the enthalpy?

Which line represents the specific volume?

Which line represents the Humidity Ratio?

An air-conditioned room that stands on a well-ventilated basement measures 3 m wide, 3 m high and 6 m length. One of the 3 m walls faces west and contains a double-glazed glass window of size 1.5 m by 1.5 m, mounted flush with the wall with no external shading. There are no heat gains through the walls other than the one facing west. Calculate the sensible, latent and total heat gains on the room, room sensible heat factor from the following information. What is the required cooling capacity?

(a)Inside conditions : 25°C dry bulb, 50 percent RH

(b)Outside conditions : 43 °C dry bulb, 24 °C wet bulb

(c)U-value for wall : 1.78 W/m².K

(d)U-value for roof : 1.316 W/ m².K

(e)U-value for floor : 1.2 W/m2.K

(f)Corrected (CLTD) for wall: 25 °C

(g)Corrected (CLTD) for roof: 30 °C

(h)U-value for glass ; 3.12 W/ m².K

(i)Solar Heat Gain (SHG) of glass ; 300 W/ m²

(j)Internal Shading Coefficient (SC) of glass: 0.86

(k)Occupancy : 4 (90 W sensible heat/person):(40 W latent heat/person)

(l)Lighting load : 33 W/m2 of floor area

(m)Appliance load : 600 W (Sensible) + 300 W(latent)

(n)Infiltration : 0.5 Air Changes per Hour

(o)Barometric pressure : 101 kPa

(p)w_o=0.0107 and w_i=0.00992

• 710.6W

• Sensible Load of Roof

• 388.8W

• Sensible Load of Lighting

• 160W

• Sensible Load of Infiltration

• 2430.65W

• Floor Sensible Load

• 163W

• Latent Load of Occupants

Identify the following cooling load components

a

b

c

d

e

i

h

g

f

j

lights

glass conduction

Glass Solar

roof

equipment

exterior wall

floor

people

partition wall

Infiltration