Cooling Load for House Design

8/2/2019 Cooling Load for House Design

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TABLE OF CONTENTS

INTRODUCTION................................................................................................................ 1

Calculations of Cooling Load for Given House Design ........................................ 2

PROPOSALS...................................................................................................................... 11

Calculations of Cooling Load for Proposed House Design .............................. 12

CONCLUSION .................................................................................................................. 17


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INTRODUCTION

In this assignment, we were given a detailed worked example which calculates the

building cooling load for an air-conditioning system. Using this work example as a reference,

we were to calculate the building cooling load for given design of a house.

After the cooling load has been calculated, we then come up with a proposal for a new

design of the house that could reduce the cooling load for the air-conditioning system.

Calculations of the cooling load for the original house design are presented in this report.

Proposals to reduce the cooling load are presented later in this report.


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CALCULATIONS OF COOLING LOAD FOR GIVEN HOUSE DESIGN

1.

2.

3.

4.

5.


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6.

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8.

9.

10.

11.


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12.

13.

14.

15. GLF

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17.

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22.


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23.

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28.


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29.


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Given cooling load

1. External

(a) Heat gain through opaque surfaces (walls, roofs and doors)

for each exterior wall

for each door

(b) Heat gain through translucent surfaces (windows and skylights)

for each window and skylight


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(c) Heat gain due to infiltration of outside air through leaks

2. Internal

(a) Heat gain due to occupants

for each occupant

for each occupant

(b) Heat gain due to artificial lighting

for each lamp


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(c) Heat gain due to electrical appliances

for each appliances

Cooling Load of Given Design


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PROPOSALS

In order to reduce the cooling load of the air-conditioning system of the house, a new

design of the house is proposed. There are few methods that could be used to reduce the

cooling load and one of them is to reduce the overall perimeter of the house which will

decrease the floor area of the house and therefore greatly decreasing the cooling load.

However this method is not used because we do not want to sacrifice the floor area of the

house as this would affect the market value of the house. Besides, the savings from the

reduced cooling load could hardly cover the inconvenience caused.

The other method that could be used is to reduce the cooling load factors such as

CLTD and CLF, however this method is not used because the procedure to reduce the cooling

load factors is complicated and references are needed to support the changes (insufficient

acquired knowledge).

The method which we used to reduce the cooling load is to decrease the internal and

external heat gained by the house, and the only way we could do that is to come up with a

proposal for a new design of the house. The new design of the house will have the following

changes:

1. The Width of the Door is decreased from 1m to 0.8m.

2. The size of the North & South Windows is decreased from (2m 2m) to (1.5m 1.5m).

3. The amount of Windows in the East & West is decreased from 4 to 3.

4. The % of electrical appliances operating is reduced from 30% to 25%.

By reducing the sizes of doors and window at North and South, heat gained by the

house can be reduced because the entrance of sun rays into the house can be limited.

Although the size reduction of the doors will increase the heat gained by opaque walls (qw)

due to increased area of exterior wall (Aw), the heat gained is insignificant compared to the

cooling load that is reduced because the heat gain through translucent surfaces (qG) is greatly

reduced. The reduction ofqG is caused by reduction ofAG in all four directions of the house

and AGS at east and west. All the calculations of the design of new cooling load will be

presented in this report.


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We also proposed that the % of electrical appliance operating could be reduced from

30% to 25% so that HA can be reduced to decrease heat gain due to electrical appliances (qA).

To achieve this, the occupants of the house should turn off unnecessary power usage

whenever possible so that the cooling load can be minimized.

CALCULATIONS OF COOLING LOAD FOR PROPOSED HOUSE DESIGN

1.

2.

3.


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4.

5.

Proposed cooling load

1. External

(a) Heat gain through opaque surfaces (walls, roofs and doors)

for each exterior wall


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for each door

(b) Heat gain through translucent surfaces (windows and skylights)

for each window and skylight

(c) Heat gain due to infiltration of outside air through leaks


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2. Internal

(a) Heat gain due to occupants

for each occupant

for each occupant

(b) Heat gain due to artificial lighting

for each lamp

(c) Heat gain due to electrical appliances

for each appliances


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Cooling load of proposed design

Daily difference in qDES

Yearly Difference in qDES

Percentage of Cooling Load Reduced


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CONCLUSION

In conclusion, reduction in heat gain through doors and translucent object such as window

will greatly reduce the cooling load of the air conditioning system of the house. With the

proposal of a new design of the house, it is calculated that approximately 923.77w of cooling

load can be reduced daily and this is equivalent to reduction of377.18 kW in cooling load

per year. The proposal of the new design of the house could reduce the cooling load of the

air-conditioning system by 10.96%. Although the percentage of reduced cooling load is not

much, but our objective is achieved, which is to propose a new design of house having lower

cooling load.

Documents

Cooling Load for House Design