1.   Obtain 2 identical shoeboxes of same color.

2.   Wrap and seal both shoeboxes with a layer of duct tape to prevent heat flow through the sides of the structure and to serve as a ?water proofing layer? for the rooftop garden.

3.   Obtain a thick rectangular box open at the top, fill the box with soil and plant a combination of grass and beans in soil.

4.   Grow a variety of edible substances in the Jiffy pellet refills to represent the impact of rooftop gardens on our food chain and to give results that are accurate for extensive rooftop gardens.

5.   Securely glue tar paper onto the top of both structures, identical tar paper must be used for both structures.

6.   Securely glue or tape the thick cardboard box onto the roof of one of your structures, this will be the rooftop garden.

7.   Put the digital probe thermometers into the side of both structures. Place a normal thermometer outside to indicate the external temperature.

8.   Place a heat lamp above the structure so equal light is shining upon both structures.

9.   Turn on the heat lamp for 60 minutes, after 60 minutes note internal temperature inside the structure as well as outside.

10.         Turn off the heat lamp for 15 minutes and after 15 minutes record the internal temperatures of both structures. This is your first cooling temperature.

11.         After another 15 minutes take another temperature reading. This will be your second cooling temperatures.

12.         Repeat this procedure 5 days to obtain the accurate results.

Results

My results support my hypothesis, the internal temperatures of the rooftop garden was significantly lower than the traditional roof. The internal temperature of the structure with a rooftop garden is much lower for all five first internal temperatures taken.  This difference is 3.68ᵒC or almost 4ᵒC on average with an average exterior temperature of 32.8ᵒC. Also, important results are the difference in the average first internal temperature and the average cooling temperature 2 of the rooftop garden and traditional roof buildings. The rooftop garden conserves more heat which will result in less fluctuation in temperatures. This will show how much heat is conserved. The difference in the two average temperatures for the rooftop garden is 0.46ᵒC or as less as about half a degree. This means that rooftop gardens conserve considerable heat after 30 minutes of cooling. For the traditional roof the difference was a much higher 4.02ᵒC in 30 minutes of cooling. This shows that the rooftop garden will conserve more energy and need less heat energy.

Conclusion

I conclude for my experiment that my hypothesis was correct. The rooftop garden building experienced much lower first internal temperatures in comparison to the traditional roof. The rooftop garden provided direct shading and effectively reduced the absorption of solar radiation or reduced insolation. The rooftop garden building also released heat less quickly because the rooftop garden would reduce heat flow through the roof and insulate the building. So, the rooftop garden will reduce the need for cooling and also, reduce need for heating. Rooftop gardens will also provide a convenient food source in urban areas. In conclusion rooftop gardens are a financially and an environmentally beneficial idea.

Research

Rooftop gardens offer many environmental friendly benefits in an urban area. In this experiment we are observing the effects that rooftop gardens have on energy demand and requirement needed. The main cause of heat buildup in urban areas is insolation. Insolation is the absorption of solar radiation and resulting re-radiation by building materials commonly used in cities such as asphalt and concrete. These materials absorb more solar radiation than natural materials. The effect of the absorbed solar radiation on the internal temperatures of houses and buildings is that this absorbed radiation is often converted to thermal energy and creates a demand for electricity for cooling. The growing medium (soil) and the plants themselves that are used in this experiment shield off the solar radiation and do not raise more than a couple of degrees above the surrounding temperatures. Other than direct shading and decreased insolation, evaporative cooling of the water in the rooftop garden should result in decreased need for cooling a building and therefore will lower the energy consumption of the building. Evaporative cooling is a phenomenon in which evaporation of a liquid usually into surrounding air cools an object or a liquid in contact with it. The amount of heat that is needed to evaporate the liquid is drawn from the outside air. For our rooftop garden then water in the plants and the soil will undergo evaporative cooling to decrease the temperature of the roof. A 2005 study by Brad Bass of the University of Toronto showed that rooftop gardens can also reduce heat loss and energy consumption in winter conditions by providing layer of insulation and reducing heat flow through the roof. Roofing membranes of the traditional roof can be affected by heat exposure to the extent where the ageing of the membrane will be increased rapidly in rooftop gardens temperature fluctuations will be moderated. These temperature fluctuations that will occur in a traditional roof will also put thermal stress on the roofing membrane further age the roofing and further deteriorate the performance of the membrane. Rooftop gardens have many benefits to people, especially those in urban settings. One reason for rooftop gardens is to contribute in urban food chain and reduce importing food supplies. This will reduce the need for trucking and the resulting GHG emissions.

Results Table: 

(RTG means building with rooftop garden and TR means building with traditional roof.)