TITLE : SOLAR POWERED ENERGY EFFICIENT AIR CONDITIONING SYSTEM

INTRODUCTION
Background information The demand of air conditioning (AC) is increasing due to the effect of
climate change caused global warming. If we still rely on the conventional electric air
conditioning system using electricity which is generated form fossil fuels, the greenhouse gas
emission would continuously worsen global warming, in turn the demand of air conditioning
would be further increasing. In subtropical cities, air conditioning is a standard provision for
buildings. However, air conditioning would commonly take up half of building electricity
consumption Most parts of Kenya are still yet to be connected to mains electricity making access
and use of electric powered air conditioning very difficult. Lack of an air conditioning system
makes indoor stay quite uncomfortable especially in hot sunny days.

METHORD
Requirements/apparatus
One model house
One thermometer( -10 -110)
One 12v DC fan
One 12v DC bulb
One plain circuit board
Connecting wires, about 4 meters
Switch ( one)
Timer switch
One 10watt solar panel
One 12v, 5Ah battery
One Arduino Uno module
One temperature sensor
LCD display screen
2 relay modules

Procedure
Place a thermometer in the model house which is kept out in the sun with the air conditioning
system off.
Measure and record the temperature in the house after every one hour for twelve hours.
Assemble the air conditioning system by connecting both the fan and the bulb to the battery
through two independent switches and DC voltage timers.
Using a laptop, program Arduino Uno to maintain the room temperature at 25 0C. after
programming, connect the module and the temperature sensor to the air conditioning system.
Leave the model house out but this time with the air conditioning system switched on.

How the system works

The Arduino is programed in such a way that when the room temperature is at 25 0C, both the fan
and the high energy bulb are off. This minimizes energy usage. When the temperature fall below
the set 250C, the bulb automatically switches on to heat up the room, up to 25 0C, when the bulb
is automatically switched off. On a hot day when the room temperature rises above 25 0C, the fan
is automatically switched on. It blows out the warm air while at the same time blowing in cool
air. The room temperature is lowered and upon reaching 25 0C, the fan automatically switches
off.

FIG 3.1 Photo 1: assembling the model house

The table below shows the changes in temperature in the house without the air conditioner.
Time of 6:0 7:0 8:0 9:0 10:0 11:0 12:0 1:0 2:0 3:0 4:0 5:0 6:0
the day 0a 0a 0a 0a 0am 0am 0am 0p 0p 0p 0p 0p 0p
m m m m m m m m m m
Temperat 17 18 18 19 21 23 24 27 26 25 22 22 20
ure(oC)
Table 1: temperature variations in room without air conditioning system

The table below shows the temperature changes for the same room in similar conditions but with
a working solar powered air conditioner.
Time of 6:0 7:0 8:0 9:0 10:0 11:0 12:0 1:0 2:0 3:0 4:0 5:0 6:0
the day 0a 0a 0a 0a 0am 0am 0am 0p 0p 0p 0p 0p 0p
m m m m m m m m m m
Temperat 17 18 18 19 21 23 22 22 22 22 22 22 20
ure(oC)
Table 1: temperature variations in room with the solar powered air conditioning system
Data analysis

Below is a bar graph of temperature against time for the room without the air conditioning
system
 30

25

20

15 17
Column1
Column2

10

0
am am am am am am pm pm pm pm pm pm
00 00 00 00 00 00 00 00 00 00 00 00
7: 8: 9: 1 0: 1 1: 1 2: 1: 2: 3: 4: 5: 6:

Graph 1.1: bar graph of temperature against time for the room without the air conditioning

Below is a line graph for temperature against time for the room without the air conditioner
 30

25

20

15 17
Column1
Column2

10

0
am am am am am am pm pm pm pm pm pm
00 00 00 00 00 00 00 00 00 :0
0 00 00
7: 8: 9: 1 0: 1 1: 1 2: 1: 2: 3: 4: 5: 6:

Graph 1.2: line graph for temperature against time for the room without the air conditioner

The graph below shows temperature changes with time for an air conditioned room
 25

20

15

17
Column1
10 Column2

0
am am am am am am pm pm pm pm pm pm
00 00 00 00 00 00 00 00 00 00 00 00
7: 8: 9: 1 0: 1 1: 1 2: 1: 2: 3: 4: 5: 6:

Graph1.3 graph of temperature changes against time for an air conditioned room
 25

20

15

Series 1
Column1
10 Column2

0
am am am am am am am pm pm pm pm pm pm
00 00 00 00 00 00 00 00 00 00 00 00 00
6: 7: 8: 9: 1 0: 1 1: 1 2: 1: 2: 3: 4: 5: 6:

Graph 1.4: Line graph for changes in temperature against time for an air conditioned room

CONCLUSION
We conclude that if well harnessed, solar power can be used to power air conditioning systems.
This reduces the cost of power as well as overdependence on power from fossil fuels. The main
challenge we faced was unavailability of motion and temperature sensors hence we were not able
to come up with a completely smart system as initially planned. However, our simple solar
powered AC system is able to maintain a relatively constant and low room temperature on a hot
sunny day.

REFERENCES
1. Billington, N.S/, Robert B>M, 1982, building Service Engineering, Pergamon Press.
Canada
2. Cowan ,H,J, 1997, Historical Outline Of Air Conditioning (Applied Science) Booklink
Puplishers.London.
3. Ingels,M., 1952, Father Of Air Conditioning, Country Life Press, USA
4. Fitch, J,M,(1999) African Buildings: The Environmental Forces That Shape It, 2nd
Edition, Shocken Books, Durban.
5. william Gryll Adams, Richard Evans(1876), Action Of Light On Selenium. United
Publishers.
ACKNOWLEDGEMENT
We take this opportunity to thank God for guiding us through this project and making it
successful. We also thank our school principal Dr. Mwaniki for giving us the financial support
required in our project and for allowing us to use the school laboratory. We also thank our
supervisor Mr. Ngechu for giving us the technical support that we needed. Finally, we appreciate
all our fellow students and the whole Gatero Girls fraternity for providing us with a conducive
environment to carry out our project. We know that without all the above support, we could not
have achieved what we have achieved today