Ambient temperature and humidity are
important factors that affect the efficiency and effectiveness of daily life
activities. This study was conducted to examine the behaviours, productivity and
comfort of the students in our experimental group at the specified temperature
A microcontroller-based embedded system was
used for this purpose and this system is designed to monitor the temperature
and humidity values of the environment. The special Arduino microcontroller we
use is enriched with sensors such as DHT11 and ESP8266, and has been turned
into a suitable working mechanism for our goal.
After the technical installation and
software operations have been completed and the device has become operational,
the determined area and the experiment group have been tested and the results
have been recorded.
Ortam s?cakl??? ve nemi, günlük ya?am
aktivitelerinin verimlili?ini ve etkinli?ini etkileyen önemli faktörlerdir. Bu
çal??ma deney grubumuzda belirtilen s?cakl?k aral?klar?nda ö?rencilerin
davran??lar?n?, verimliliklerini ve konforlar?n? incelemek amac?yla yürütüldü.
Bu amaçla bir mikro denetleyici tabanl?
gömülü sistem kullan?ld? ve bu sistem ortam?n s?cakl?k ve nem de?erlerini
izlemek için tasarland?. Kulland???m?z özel Arduino mikroi?lemcisi, DHT11 ve
ESP8266 gibi sensörlerle zenginle?tirildi ve hedefimiz için uygun bir çal??ma
Teknik kurulum ve yaz?l?m i?lemleri
tamamland?ktan ve cihaz devreye girdikten sonra belirlenen alan ve deney
grubunda gerekli testler yap?lm?? ve sonuçlar kaydedildi.
First and foremost, we have to thank our
project supervisor, Mr. Gökhan Kirkil. Without his assistance and dedicated
involvement in every step throughout the project, this paper would have never
been accomplished. Also, special thanks to Mr. Orçun Kepez for his help and
many precious ideas about our discussion. We feel very lucky to had the
opportunity to work with him. We also take this chance to express gratitude to
all of the Kadir Has University Engineering and Natural Science Faculty members
for their help and support in all four years.
First of all, we want to mention some basic
concepts. Heat is a form of energy measurable in terms of temperature by
thermometers. In a natural environment, human body can experience extreme heats
which is in a range of arctic cold to tropical heat. And the temperature of the
environment influences the body temperature.
Indoor temperature is one of the
fundamental characteristics of the indoor environment. It can be controlled
with the building and its HVAC system. HVAC is the system of heating,
ventilating and air conditioning.
According to researchers, the best indoor
temperature for daily living is 293 K, 20 ° C or 68 ° F. We call it the best
condition because the indoor temperature affects several human responses such
as thermal comfort, perceived air quality and performance at work. In this
study, we focused on the effects of temperature on performance at our school.
Latest researches shows that extreme indoor
environmental conditions can affect health and productivity in a negative way.
So engineers are interested in improving indoor environments and their effects
to increase efficiency. We collect the existing information and tried to get
new test information on how temperature affects productivity and efficiency.
Because when we know more about these effects, they could be included into
cost-benefit calculations for the building design and operation.
2.1 Previous Studies
Temperature’s effect on productivity is an
important topic for researchers. There are lots of example studies about it. In
this paper, we will talk about G, NECA and T’s original research
data about temperature and productivity relationship.
‘Grimm and Wagner (1974) and The National
Electrical Contractors Association (NECA 1969, NECA 2004) conducted experiments to measure
productivity under different weather conditions. Thomas and Yiakoumis (1987)
developed a regression model using temperature and humidity to predict PR.’
(Ibbs & Sun Analysis of the MCAA Factor Model for Measuring Loss of
*The Productivity Ratio (PR) represents the
ratio of actual productivity divided by “optimal” productivity.
2.2 Embedded system
In this thesis, our microcontroller-based
embedded system is designed to monitor the temperature and humidity values of
the environment. In addition to monitoring temperature and humidity, we can
control the heat index too. Heat index is a combination of air temperature and
relative humidity. It also called ‘humiture’.
2.2.1 Heath Index
Heat index is what the temperature feels
like to the human body when relative humidity is combined with the air
temperature. This has important considerations for the human body’s comfort.
Here is the equation of heath index when t
representing the current air temperature and r representing the current
2.2.2 Microcontroller Unit (MCU)
We designed the system using Arduino Nano
microcontroller. A Microcontroller (MCU) is basically a simple computer. The
difference desktops and microcontrollers is that a desktop can run any number
of programs and has software support for different hardware components.
Microcontrollers generally only run one program. In general, this program is
specifically written to control known hardware components.
Arduino webserver monitoring system was
programmed using the C programming language. The sensor data is read and
processed by Arduino and it is displayed to the user through the Gobetwino
We create the embedded system in two parts.
System design was the theoretical part.
This part describes, explaining the use of the Arduino microcontroller and how
it is utilized in the embedded systems in practical part. We create the design
and architecture model in this phase.
Practical part describes the temperature
and humidity monitoring system. This part of the project is divided into two
parts: Hardware and Software. Practical part includes the wiring diagram and
the source code and it was the phase we did implementation and testing.
Temperature and Humidity Sensor
We get the measurements of the class via
Arduino Nano heat and humidity calculation device which we build and encode. We
use Arduino Nano, DHT11 humidity and temperature sensor to build a small
circuit for measurements and ESP8266 Wi-Fi module and Gobetwino for getting the
data and save them in a txt format.
Some details about the components which we
Technically, Arduino is a programmable
logic controller. Officially, it’s an open-source electronics prototyping
platform. Basically, Arduino boards are able to read inputs (ex. message, heath or light) and turn it into an
output (ex. turning on led, activating a motor, display it in the screen). You
can tell your board what to do by sending a set of instructions to the
microcontroller on the board. For example, you can obtain some test results
using customized Arduino components for humidity and temperature measurements,
as we did in this experiment
In this study we use Arduino Nano which is
a common type of Arduino to use. The major difference between the standard
Arduino Uno and Arduino Nano is the number of Analog Pins and the USB Port We
will discuss these components later in detail.
Advantages of Arduino
Inexpensive – Arduino boards are relatively inexpensive compared to
other microcontroller platforms.
Cross-platform – The Arduino Software runs on many operating systems. It
is not limited to Windows.
Simple, clear programming environment – The Arduino has an easy-to-use
software and it is flexible to develop.
Open source and extensible software – The Arduino software is an open
source tool so programmers can add extensions.
Open source and extensible hardware – Circuit designers can extend and
improve it to make their own version of the module.
4.1.2) Arduino IDE
The Arduino Software is a user friendly
programming environment: It allows the programmer to create different programs
and load them to Arduino microcontroller. The software also called Arduino IDE
(Integrated Development Environment).
DHTXX series there are two types of humidity sensors, DHT11 and DHT22. Both
these sensors are Relative Humidity (RH) Sensor.
According to the Australian Bureau of
Relative humidity (RH)
The ratio of the actual amount of water
vapour in the air to the amount it could hold.
Absolute humidity (AH)
The mass of water vapour in a unit volume
result, we can measure both the humidity and temperature.
In our project, we used DHT11 is a Humidity
and Temperature Sensor, which generates calibrated digital output. It can be
interface with Arduino and it can get instantaneous results. DHT11 provides
high reliability and long term stability.
The DHT11 Humidity and Temperature Sensor
consists of 3 main components. A resistive type humidity sensor, an NTC
(negative temperature coefficient) thermistor (to measure the temperature) and
an 8-bit microcontroller. This microcontroller gets analog signals from the
sensors and converts them to a single digital signal to send out.
You can see the main specifications and
differences between these two sensors in table 111. The more expensive option,
DHT22 has some better specifications. DHT22 has a wider temperature range. When
DHT11 can measure the temperature in 0 to 50 degrees, DHT22 can measure it in
-40 to 125 degrees. Also with +- 0.5 degree accuracy, DHT22 has more reliable
results than DHT11. About humidity, DHT22 has better humidity measuring range,
from 0 to 100% with 2-5% accuracy, while the DHT11 humidity range is from 20 to
80% with 5% accuracy.
There are some specifications which DHT11 is
better than DHT22. They are sampling rate and body size. Sampling rate for
DHT11 is 1Hz or one reading every second, while the DHT22 sampling rate is
0,5Hz or one reading every two seconds and also the DHT11 has smaller body
These two sensors has the same operating
voltages (from 3 to 5 volts) and same max currents (2.5mA) used when measuring.
Gobetwino is kind of a “generic proxy” for
Arduino. It’s a program which is running on your computer and act on behalf of Arduino
and do some of the things that Arduino can’t do on its own.
We use Gobetwino program for display the
data we get from the humidity and temperature measurements with Arduino. And we
save them as a text file on Gobetwino.
Before beginning to monitoring the class,
certain requirements were set. The system is needed to be easy to use and the
user could remotely monitor environmental changes inside the class. Sensor data
required to be collected and stored for showing changes in the environment
variables. We had a fixed temperature to get reliable results.
The measurements accomplished by the data
communications between Arduino, DHT11 Sensor Module, ESP8266 WIFI module and
Gobetwino. Arduino’s Celsius scale thermometer and percentage scale humidity
meter displays the ambient temperature and humidity through Gobetwino display
and also record it as a text file.
We take the measurements on 30.11.2017 and
07.12.2017, 2 weeks consecutively, in smart class of Kadir Has University. We
take two measurement tests by Arduino each day. One is before the class when
the lecture didn’t start and one is after the lecture, while the students write
their reflection papers about the lecture and filling our survey questions.
We try to figure out their comfort level in
the temperature we fixed by HVAC system and their motivation in this
environment. First week we fixed the classroom temperature at 20.00 C ° and the
second week we fixed it at 27.00 C °. There were 26 people in the test group
and we neglected the genders and clothes while we commentate the results.
For this experiment, we divided the class
into eleven regions. We gave a number to each region and recorded the results
of each region separately. We ensured students sit in the same places in the
two days of experiment. At the end of the class we asked the students to write
a reflection paper about the lecture and to answer the survey questions which
we gave them before the class. We asked them for mark where they sit in class
on the graph we gave them and mark the spot they want to sit if it is possible.
A systematic approach has been followed in
measurement with the microcontroller based system. The results obtained from the measurement
have shown that the system performance is reliable and accurate. This project
has been completed successfully. We get our data with Arduino and transmit them
wirelessly to a processing sketch, where they are visualized for simple
analysis. So our goal of integrating all of the underlying technologies has