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HYDRO-ROOF A HYDROPONIC GREEN ROOF SYSTEM IN THE DESERT

Green roofs are a popular sustainable strategy among architects and landscape

architects. They are being incorporated to help with rainwater runoff mitigation a strategy known to reduce the Urban Heat Island (UHI) Effect.

However, in a hot arid climate they exacerbate rather than mitigate the UHI. This is due to the high thermal storage capacity of soil required to sustain the green roof. UHI is a night time, rather then a daytime phenomenon, in such a climate.


Base Case Data_July 8,2011 180.00 160.00 140.00

Temperature (deg. F)

120.00 100.00 80.00 60.00 40.00

Time Surface Temperature

Test Cell 1_Saltillo tile_July 14, 2011 120.00

80.00

70.00 100.00

80.00 50.00

60.00

40.00

30.00 40.00 20.00 20.00 10.00

0.00

0.00

Time Surface Temp. (deg. F)

Ambient Air Temp. (deg. F)

Growing Medium Temp. (deg. F)

"In-between" Temp. (deg. F)

Temp. above growing medium (deg. F)

Relative Humidity (%)

Test Cell 2_Shaded 100.00

120.00

90.00 100.00

80.00 70.00

Temperature (deg. F)

80.00

60.00 60.00

50.00 40.00

40.00

30.00 20.00

20.00

10.00 0.00

0.00

Time Surface Temp. (deg. F)

Ambient Air Temp. (deg. F)

Growing Medium Temp. (deg. F)

"In-between" Temp. (deg. F)

Temp. above growing medium (deg. F) Relative Humidity (%)

Relative Humidity (%)

60.00

Overnight studies of three test cells have been

conducted during the month of July, 2011, in Tempe, Arizona. The results show both alternatives mitigate the UHI and provide additional benefits.

Ambient Air Temperature

Relative Humidity (%)

In order to make green roofs a sustainable strategy in a hot arid climate, the thermal performance of the hydro-roof was evaluated as a possible alternative.

0.00

Temperature (deg. F)

THE EXPERIMENT

20.00


BASE CASE TEST CELL

BENEFITS

It offers the benefit of increased biodiversity. Biodiversity is of great importance as it boosts the overall ecosystem productivity.

It improves thermal properties through external temperature regulation. Because the urban temperatures would be reduced the air quality would be affected positively. For example, the reduction of smog and air born particles. The reduced overnight temperatures could increase the amount of precipitation and reduce the

occurrence of dust storms.


TYPICAL ROOF ASSEMBLY

Construction

Sensor placement

BASE CASE


SALTILLO TILE

Construction

Sensor placement

TEST CELL 1


WITH SHADE STRUCTURE

Construction

Sensor placement

TEST CELL 2


POTENTIAL

URBAN AGRICULTURE

The Hydro-Roof offers a potential for urban agriculture. By using abandoned space, food can be grown locally which is becoming more desirable due to the

lack of space for food production within a city. Additionally, the rising prices of fuel cause the food prices to increase. Additional benefits include marketing of green branding a local job creations due to required maintenance and operation.


Hydroponic Green Roof System