12. Job done. But did it work?
Time to see if it worked!
After finishing our rooftop garden we needed to start collecting data once again to see if the project would eventually help lower temperatures inside our classrooms. We started right away to collect temperatures. We could do that because grass is already a full plant and we didn't need to wait for it to grow. For two months we collected data, calculated the daily average temperature. Finally we calculated the average temperature of the classrooms for both the Control and Experimental classrooms. Average values were:
Average Temperatures Classroom #1 (Control) vs Classroom #2 (Experimental)
Classroom 1 Average Temperature Inside
Classroom 1 Average Temperature Outside
Classroom 2 Average Temperature Inside
79.7 °F 26.5°C
Classroom 2 Average Temperature Outside
Difference in temperatures between classrooms
Classroom #2 with the Rooftop Garden
2.49 ° F
Temperatures Registered INSIDE Classrooms During Experimentation
|Here you can see that INSIDE the classroom with the rooftop garden (red line)temperatures were cooler with an average of 79.8 F; compared to the one without it (blue line) who's average temperature was 82.2 F.|
What the data shows?
1.There is a difference of 2.49 °F (1.3 °C ) DEGREES COOLER INSIDE the classroom were the rooftop gardens were placed directly on top.The average temperature INSIDE the classroom with the Roof Garden was 79.7°F while on the classroom without roof garden it was an average of 82.19°F. That makes the difference of 2.49°F
2.On the OUTSIDE, the rooftop garden is 6.99 °F (3.89 °C) cooler that the “control” rooftop.Meanwhile the temperature OUTSIDE on the Rooftop Garden was 86.09°F vs. 93.08°F on the control room. That makes a difference of 6.99°F on roofs what were side by side!
3.A similar pattern on the temperatures can be seen on first weekThis happened because it took about a week for an actual change in temperatures to occur and been noticed. Planted areas start to insulate the area gradually and concrete takes time to loose heat. After a first week is where yo can see dramatic changes in temperatures showing the actual minimum temperature of 75.2°F.
4.There's an unusual read from Feb 27 to March1 temperatures inside control classroom.On those date the control classroom reached a lower temperature than the actual experimental room. That can be explained because during that week the control classrooms were not in use during all day and temperatures were taken without students inside making them cooler while the experimental classroom had students all day.
Temperatures Registered OUTSIDE Classrooms During Experimentation
|On this graph you can see that OUTSIDE the classroom with the rooftop garden (RED line)temperatures were cooler with an average of 86.09°F; compared to the one without it (BLUE line) who's average temperature was 93.08°F.|
But how a difference of 2.4°F can affect us?
You might think that a two or three degrees change is no big deal, but that actually a rise on body temperature of that magnitude can be life treatening. According to the document "Heat Stress", created by the Ohio State University (OSU) Agricultural Safety Program (N.D), an increase in body temperature of two degrees Fahrenheit can affect mental functioning and five degree Fahrenheit increase can result in serious illness or death by "heat stress".
Heat stress (OSU, N.D.) is a buildup of body heat generated either internally by muscle use or externally by the environment. As the heat increases, body temperature and the heart rate rise painlessly. During hot weather, heat illness may be an underlying cause of other types of injuries, such as heart attacks and falls.
The most serious heat related illness is heat stroke. The symptoms are confusion, irrational behavior, convulsions, coma, and death. While over 20% of heat stroke victims die regardless of health or age, children seem to be more susceptible to heat strain than adults. In some cases, the side effects of heat stroke are heat sensitivity and varying degrees of brain and kidney damage (OSU, ND).
Any heat stress can impair functioning. People work slower and less efficiently when they are suffering from heat stress. Heat stress is serious and should be handled as such. As strain from heat increases, body temperature and heart rate can rise rapidly. Exposure to heat can be serious to children and adults, concludes the document.
Signs and symptoms of heat stroke and heat exhaustion
How about the Thermal Comfort Satisfaction?
According to the American Society of Heating, Refrigeration and Air- Conditioning Engineers (ANSI / ASHRAE) (2004) thermal comfort is defined as the state of mind in humans that expresses satisfaction with the surrounding environment. It’s also known as the “Perfect Temperature”, because is on that range of temperature where people can perform comfortably.
If you think about it, thermal comfort is definitely different to every people and to every area of the world, but according to Sonia Cosme (2012), biologist of the environmental company EDS, here in Puerto Rico and in most tropical areas thermal comfort temperatures range from 73 – 79 °F (23 - 26°C) . Below or above these temperatures people feels uncomfortable enough so they are distracted to perform tasks.
All of this is very important to know, because:
- By building a green roof we achieved to lower the inside temperature to an average 79.7 °F, almost reaching the threshold of what is thermal comfort.
- If we can reach that range for the “perfect temperature” we might be improving the thermal conditions inside the classroom,
- mproving students comfort temperature zone which eventually could create a more pleasant environment for both teachers and students
ANSI/ASHRAE (N.D) also states that thermal comfort is closely related to
, which lowers peoples performance about 11% compared to their performance at normal thermal conditions
. Also, human performance in relation to thermal stress varies greatly by the type of task you are completing. Some of the physiological effects of thermal heat stress include increased blood flow to the skin, sweating, and increased ventilation.
With roof gardens we lower our ecological footprint on the WORLD: HOW? Figure this. Comfort temperature is often used in stores to create a pleasant space for the buyer and worker so they stay longer. So if, we can reach that thermal comfort temperature through building Roof Gardens, there would be no need for air conditioning systems and we would end saving LOTS of money because, according to the web page hubpages.com (2012) for every 1°C cooler could increase your power costs by about 10 to 15%. Call tha an ECO saving!!
But..Have people felt the thermal difference?
Mrs. Rosita Rosario, Teacher.
My classroom is the one beneath the garden the kids created and it's amazing how you can feel the difference. I don't have to use the fans anymore and students really feel the difference. It feels a lot cooler now.
Mr. Colón, Social Worker.
Without knowing which classroom was the one with the rooftop garden I asked Mr. Gonzalez, the students coach, if Mrs. Rosario classroom was the with it. As soon as I stepped inside her classroom I noticed a difference in the temperature. It felt cooler than the classrooms right beside that one. I knew that had to be the one, and I was right!
Mrs. Mirtha Mendez, HistoryTeacher.
My classroom is the "control" classroom without the roof garden. I hope they extend that garden to mine, because my students and I still feeling our classroom is hot. I have visited the green roof classroom that is just beside mine and there is truly cooler.
Madeline, Ninth grade student.
I feel the difference in temperature when I compare it to other classrooms. No longer I have to fight over getting some ventilation from the fans in the classroom. We don't even have to turn them on because the temperature feels cooler
Mr. Hector Haddock, English Teacher
Definitely I can feel the difference, I could tell it feels about four degrees cooler. (Mr. Haddock teaches on the classroom used as experimental where the roof garden was constructed on top of it)
Does students feel clasroom is cooler after planting?
|We decided to conduct a poll again to the 157 students that took the poll prior to staring the roof garden to see if students actually feel a change in temperature inside the classroom with the Roof Garden. 88% did feel is cooler! It worked!|
Daily temperatures AFTER planting
Here you can download the data table showing all the temperatures we took during the 24 days of experimentation.
On February 22, 2012 the difference between the outside of the classroom and the inside was 20 degrees Fahrenheit cooler inside (104 °F vs. 83.9°F) or 12 Celsius (40°C vs. 28.8°C) !!
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