Green Roofs in Egypt

Application of Green Roofs

in Cairo

By: Mahmoud Sherif Saad

Cairo University Faculty of Engineering AET/Fall 2010 Independent Studies

Jan, 2011

Introduction

Air Pollution in Cairo is 10 to 20 times what is considered a safe limit. (1)

Imagine that one jet crashing and killing about 1000 daily for 15 years (1)

(1) Dr. Salah Hassanein, “Air Pollution in Cairo - The Cost” Arab World Books Articles 11-2010 http://www.arabworldbooks.com/articles1.html

The Problem

http://www.arabworldbooks.com/articles1.html

Introduction

Technical guidelines about the construction of Green Roofs

Estimated environmental benefits for Green Roofs

Objective Will Green Roof

protect me?

Outcomes

Part-1Literature Review

Definitions

Air Pollution concentrations

in Cairo

SO2 concentration NO2 concentration

PM10 concentrationO3 concentration

Part-1

(2) “Air Pollution”, 12-2010,http://library.thinkquest.org/26026/Economics/pollution_problems_in_the_thir.html

Literature Review

DefinitionsAir

Pollution in Cairo

Every day, the average person inhales about 20,000 liters of air. (2)

NO2, SO2, O3, PM10most caused by fossil fuel-burning power plants and automobiles that combust fuel.

Sunlight, hydrocarbons, and nitrogen oxides have to mix together.

Part-1

(3)“Green Roofs Benefits”, International Green Roof Association11-2010, http://www.igra-world.com/benefits/index.php

Literature Review

Benefits

Private

Public

Increased roof life Reduced Noise Levels Thermal Insulation Heat Shield

Reduction of dust and smog levels Urban heat island effect Natural habitat for animals and plants Visual effect of cities and landscape

http://www.igra-world.com/benefits/index.php

Part-1

(4) “Types of Green Roofs”, International Green Roof Association11-2010, http://www.igra-world.com/types_of_green_roofs/index.php

Literature Review

Types of Green Roofs

Extensive

Semi-Intensiv

e

Intensive

low maintenance, Low or no irrigation, build-up height 60-200mm Weight 60-150 kg/m2 Moss-Sedum-Herbs and Grasses

Periodical maintenance, Periodical irrigation, build-up height 120-250mm Weight 120-200kg/m2 Grass-Herbs and Shrubs

High maintenance, Regular irrigation, build-up height 1250-400mm Weight 180-500kg/m2 Lawn or Perennials, and Trees

Part-1

(5) “Green Roofs Engineering”, International Green Roof Association11-2010, http://www.igra-world.com/engineering/index.php

Literature Review

EngineeringR

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Part-2

(6) “Removal of air pollutants by green roofs”, 12-2010http://www.slrss.cn/download/

Case Studies

City Scale

Study site

Survey of green roofs in Chicago

Removal of air pollutants by Green

Roofs

Quantifying air pollution removal by green roofs in Chicago

Chicago, Illinois Pop.= 2.9 million in 2000

170 Green Roofs reduced to 71 after verification

Percentage of green roof to total area Error margin =1% or smaller

Q = F x L x T Q is the amount of a particular air pollutant

removed by certain area of green roofs in a certain time period (g)

F is the pollutant flux (), L is the total area of green roof () T is the time period (sec). Hourly air pollution data including NO2, SO2, O3,

and PM10 concentration from an air pollution monitoring station

Part-2


Case Studies

City Scale

Results


198,000 m2, 63% short grass, 14%large herbaceous plants, 11% trees and shrubs. And 12% various hard surfaces

The total air pollution removal by 19.8 ha of green roofs was 1675 kg between August 2006 and July 2007.

O3 has the largest uptake of 52% of the total uptake followed by NO2 (27%), PM10 (14%), and SO2 (7%).

Part-2


Case Studies

City Scale

Conclusion


If this case study proved that a total of 1675 kg of air pollutants were removed by 198,000 sq.m. extensive and intensive green roofs in one year; it can be concluded that for a 400 sq.m. green roof, 3.22 kg of air pollutants can be removed.

Part-2Case Studies

Building Scale

Green Roof Design

Seattle City Hall, Seattle, WA

1250 m2 roof is planted with 5,600 pots The runoff from the roof goes into a

30,000 cubic foot rainwater This water is then used for toilet flushing

Part-2Case Studies

Building Scale

Green Roof Characteristic

s


Existing Roof/ New Roof: New Roof

Green Roof Area 13,200 square feet

Green Roof Type Extensive

Green Roof System American Hydrotech Inc.

Accessibility Maintenance only

Installation season Fall 2003

Establishment Period Six months

Slope of existing Roof Flat

Soil Mix/ depth 6 inches

Plant Type Drought tolerant plants

Irrigation Yes

Structural Load 50 lbs/sq.ft

Cost $2/sqft

Part-2Case Studies

Building Scale

Cross Section & Details


Part-2Case Studies

Building Scale

Challenges


No operations and maintenance manual exists

The intent was to irrigate the roof for just the first year

Access to the roof is through a small room that has a vertical ladder which is difficult to carry tools through it

The water used for toilets is yellow in color because of the green roof soil and there was a lot of complaints

Part-3GUIDELINES

Guidelines for local Green

Roofs

Challenges

local Green Roofs Reinforced concrete is most widely used in the

residential buildings in Cairo. A check for load bearing capacity is essential before building the green roof

Water proofing must meet the requirements for the root resistance test or else an extra root barrier has to be installed

Up stand height for adjacent building parts and penetrations: minimum of 150 mm. Up stand height for roof edges: minimum of 100 mm (4 in).

Slope must not be greater than 10 degrees Simple extensive green roofs weigh between

60-150 kg/m2. once the cement tiles are removed, Extensive Green Roof can be installed without increasing the assumed load

Part-3GUIDELINES

Guidelines for local Green

Roofs

Challenges

local Green Roofs Because Cairo has very low rain intensity,

number of roof outlets doesn’t have to be much but an inspection chamber has to be placed over them for maintenance.

Simple Extensive Green Roofs with drought resistant plant species have to be irrigated only during planting and installation maintenance over the first year.

50 cm vegetation free zones at every opening

Access to the roof has to be guaranteed throughout the installation and for annual maintenance and service of the Green Roof

Part-4APPLICATION OF THE GUIDELINES ON A LOCAL CASE

Local Application (Building

Scale)

local Green Roofs

Figure 19b (38, Abdullah Ben Taher St., Nasr City) Google EarthFigure 19a(Schematic section)

The selected local application is a residential building located in Nasr City, Cairo with a roof area of 400 m2 and will be planted with an extensive Green Roof.


Local Application (Building

Scale

Before and After

local Green Roofs The actual building roof was covered by cement tiles which were

removed to reduce the dead load and add the green roof safely. For insurance that the roots will not penetrate the water insulation,

an extra protection board was installed on the concrete slab. Insulation and water drainage layers were installed. Filter Fabric and soil mix which included sand, compost and

nutrients. A roof access room was built and an automatic irrigation system

for irrigating the plants for the scarcity of rain in Cairo, short grass, shrubs and small plantings were planted.

Figure 20(3D rendering for building no. 38 before and after building green roof using 3ds max)


Local Application

(Urban Scale)

local Green Roofs

Figure 21(selected Area in Nasr city; 1,300,000 m2)Figure 22 (3d rendering for Building no. 38, the prototype)

Taking Building no.38 as a prototype for Green Roofs in Cairo, the research will try to repeat this prototype allover a specific land in Nasr City


Local Application

(Urban Scale)

Before and After

local Green Roofs

Area = 1,300,000 m2 Average roof area =500m2 No. of buildings = 1400 Total Roof Area = 1400x500=700,000 m2 Assumed that 80% of Roof Area is green Green roof area =700,000x0.8= 560,000 m2

Figure 23 (3d rendering showing the buildings in the selected area before and after creating the Green Roofs)


Local Application

(Urban Scale)

Conclusion

local Green Roofs

Chicago Example showed that for every 400m2 of green roofs, 3.22 kg of pollutants are removed. The total removal of pollutants can be calculated as: (560,000/400) x 3.22= 4648kg

4648kg of pollutants can be removed annually by creating extensive green roofs all over the selected area in Cairo

Figure 23 (3d rendering showing the buildings in the selected area before and after creating the Green Roofs)

THANK YOU

Green Roofs in Egypt

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