ENGR103 GRP06603 POSTER .pdf
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Author: Anita Ting
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RetroﬁVng Rooﬁng Systems
by Bridget Frasca, Hope Lewis, Anita Ting
Advisors: Dr. Masoud Soroush, Nathan Taylor
Drexel U niversity
Figure 1. First house is with conven/onal rooﬁng with ultraviolet rays
entering the home, while the second house is with cool-‐rooﬁng
• The primary goal of this project was mo/vated by the
ul/mate need to determine an alterna/ve to a
tradi/onal rooﬁng system, constructed of more
sustainable, energy eﬃcient materials that reﬂect
• Exis3ng solu3ons to this problem have been found to
be the employment of:
• Green roofs
• White/lighter colored roofs
• Heat-‐resistant material
• A\empted to quan/fy the diﬀerences between rooﬁng
types in terms of absorp/on of heat
• Generaliza/ons were made about the performance of
diﬀerent materials in a climate in which absorp/on of
heat would be a signiﬁcant issue
• Rooﬁng materials for tes/ng were selected according
to their heat transfer capabili3es, speciﬁcally their
thermal conduc,vity and resis,vity, cost and
• The conclusion that was to be drawn from the data
collected was the material that absorbed the least
amount of heat, thus would perform the best in such a
RESEARCH POSTER PRESENTATION DESIGN © 2012
• To control the experiment with the type of rooﬁng being
the only variable, a heat lamp was used, which produced
a constant, high temperature that would simulate long
hours under the sun.
• The prototype design was a constructed box with
12”x12”x10” dimensions, featuring interchangeable
roofs of varied materials that were chosen to eﬀec/vely
test, shown in Figure 2 and 3.
• The ﬁnal deliverable was the results of the data collec/on
and analysis, showing the best material in terms of
• From using the equa/on q=S·∙U·∙(Tout-‐Ti)n+qrad, ﬁnal
experimental U-‐values were calculated. In order of lowest
U-‐value to highest:
Table 1. Results of analysis through equa/on
2. Experimental prototype with thermal
Figure 3. Experimental rooﬁng types
couple and green roof sample
• A small hole was drilled into a side of the box for
inser/on of one probe from the thermocouple, and the
other probe was placed close to the surface of the roof
to compare both temperatures.
• A thermocouple was used to measure the change in
temperatures every 30 seconds for the ﬁrst 5 minutes
and then every 10 minutes for 2 hours.
• ARer data was collected each material was evaluated on
eﬀec/ve insula/ng performance, seen in Figure 4.
Inside Temperatures over Time
Temperature Inside (in Celsius)
• Many rooﬁng types are not always suited to the
climate in which they are used. A roof that would
perform well in a temperate climate would not
necessarily perform with similar results in a warner
• Solar radia3on can enter buildings directly through
the roof, therefore proper insula,on in a warm
climate is necessary to help reduce the heat transfer
through the building envelope, as seen in Figure 1.
• The primary focus of this project was to iden3fy a
more energy eﬃcient system of a building’s
insula3on through study and experimenta/on,
speciﬁcally through the rooﬁng system, to reduce
energy consump/on due to hea/ng and cooling.
• The desired end result would amount to a more cost-‐
eﬃcient system when maintained for a long /me
• As seen in the Table 1, the green roof prototype absorbed
the least amount of heat and transferred it to the room
• The green roof would perform the best in terms of
reducing the amount of heat absorp/on.
• Darker materials, the black asphalt and the rubber,
performed the worst in experimenta/on
• Lighter materials, white thermoplas/c and aluminum,
performed be\er, showing the role that the color of the
material has in reﬂec/ng radia/on before it can become
• Each rooﬁng type was analyzed according to the average
respec/ve material and installa/on costs per square foot
in the hot climate of Miami, Florida. 
Table 2. Es/mated cost per square foot of chosen materials
Figure 4. Graph of results from experimenta/on
• Using the value of the slope from each graph, a value of
q was found using the equa/on for heat energy
• From the result of q, using the equa/on for heat transfer
or heat ﬂow, q=S·∙U·∙(Tout-‐Tin)+qrad 
• Solving for U gives the conduc3vity of each material,
used to compare the materials and determine the best
• The best rooﬁng type, in terms of increased energy
eﬃciency, was the green roof, which tested with the
lowest conduc,vity of .03071 W/°C and therefore the
highest resis,vity, 32.5627 °C/W. It was the most
expensive however, with a cost of $10 per square foot.
• Has a natural ability to cool through soil
temperature and growth of greenery 
• Aids in increased thermal resistance and
capacitance of a building roof
• A green roof is more expensive to implement and more
diﬃcult to maintain, which is not reﬂected in energy
costs. However, over the course of the life of the green
roof, the energy cost savings oﬀset the ini/al cost.
• It was found that the white thermoplas3c was a
cheaper alterna3ve, which performed just as well with a
signiﬁcantly minimal cost.
• Maintains a high-‐temperature tolerance and
low-‐temperature ﬂexibility, which is most
resistant to ultraviolet and ozone exposure 
• Steps that would need to be taken to improve through
future work include extending the period of /me for data
collec/on and it would be preferable to test mul/ple
• Will u/lize the realis/c condi/ons of climate for more
• Crea/ng individual prototypes to house each respec/ve
rooﬁng type would also evenly distribute the tes/ng
• Would provide less room for human error, but produce
more uncontrolled variables, such as the changing
• The green roof is the most expensive of the materials in
both installa/on and maintenance costs, with the asphalt
shingles, rubber, and thermoplas/c being cheaper.
• Metal rooﬁng resulted in a median material cost, but
proved to be low in maintenance costs due to its
 W. T. Grondzik and A. G. Kwok, “Design Strategies,” in The Green Studio
Handbook, 2nd ed.
 N. Sturdevant, Reﬂec,ve Roofs Return Mul,ple Dividends
 Thermal Energy h\p://physics.weber.edu/schroeder/eee/chapter3.pdf
 Basics of Heat Transfer
We would like to acknowledge the guidance and advice of
our advisor Dr. Masoud Soroush and our teaching
assistant, Nathan Taylor. Also, we would like acknowledge
Von Schiﬀerdecker for allowing us to use some technical
equipment for our tes/ng.