cooling load for house design
TRANSCRIPT
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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
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15. GLF
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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
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4.
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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.