The Execution of a Green Roof Design. Analysis, Assessment, Concept and Design

Wissenschaftliche Studie, 2015

12 Seiten


Table of Contents

Part 1: Client Brief and Site Analysis
Client Brief
Anticipated Outcomes for the green roof
Feasibility Analysis of the Outcomes
Storm Water Management
Air and Noise Pollution Reduction
Heating and Cooling Mechanism for the building
Reducing the Urban Heat Island
Extension of roof life span
Attractive Roof top
Assessment of the Environmental, Social, and Economic Impacts of the Green Roof Technology
Construction Phase
Negative Impacts
Positive Impacts
Operation Phase Impacts
Negative Impacts
Positive Impacts

Part 2: Concept Design
Technical and Habitat Considerations
Botanical Name
Common Name

Part 3: Final Design
Figure 2 Plan View Scale 1:76
Figure 3 Plan View Key
Figure 4 Horizontal View of the extensive green roof's material layers
Figure 5 Final Model of the green roof on the building
Planting Schedule
Maintenance Schedule for Robin’s Center Green Roof Systems
Spring Schedule
Autumn Schedule


Part 1: Client Brief and Site Analysis

Client Brief

- The client requires a specially engineered rooftop that supports plant life, measuring 37m by 44m.
- They requested for a rooftop with a thin layer of low-growing, herbaceous plants that require low maintenance, thus an extensive green roof. The roof had to be a multi-layered build up consisting of a protection fleece layer and a re-cycled filter fleece under a loose blend of organic and mineral substrate under a planted sedum vegetation.
- Given the Australian climate, the plants should be densely spaced and able to live in meager soil and also survive exposure to cold, heat, and wind.

Anticipated Outcomes for the green roof

1. Storm water management
2. Reduction in the “Heat Island Effect”
3. Reduced cases of air and noise pollution
4. Extended life of the rooftops
5. Provision of a heating and cooling mechanism for the building
6. An attractive rooftop as an alternative to the traditional rooftop

Feasibility Analysis of the Outcomes

The increasing global concern for the environment has led to the development of environmentally friendly constructions. The adoption of the green roof technology is perhaps a solution to the environmental impacts of a building. The Collingwood-based Robin’s Landscape Designers Company is considering installing a green roof on part of the new Robin Center in a bid to enhance the company’s image as an environmental conscious. The company has thus enlisted the assistance of our consulting team to investigate the feasibility and the eco-social-economic impacts of the project.

Storm Water Management

According to the United Nations (2002), storm water management is a term used to describe the control of discharge and runoff resulting from rainfall on a particular area. Urban areas like Collingwood make use of storm water management due to their increased impermeability to rainfall infiltration as a function of roads, roof, and parking lots among others. The rationale of storm water management is to attenuate the increased runoff to conditions and levels that the receiving watercourse is capable of handling. Green roof technology is an effective Storm Water Management control method.

Storm water management is subdivided into two categories: water quality control in terms temperature, bacteria, dissolved minerals and suspended solids, and erosion control. Green roofs offer a unique storm water management opportunity especially in the urban areas where land is scarce for the traditional storm water management facilities. Reduction in the volume of storm water runoff from green roofs will reduce flow duration and velocity; hence reduce the erosion on the immediate and surrounding environment of Robins Center. Consequently, the reduction in erosion results in improved water quality as the suspended soil material within the flow will be reduced in quantity. This also improves the town’s drainage systems stability and reduces the frequency of their maintenance and rehabilitation. According to Marinova, Annandale, and Phillimore (2006), a large percent of Phosphorous is carried though air and this amount co-relates to the suspended solids. Studies have revealed that green roofs absorb these minerals to levels recommended by the Ministry of Environment with respect to storm management (Graham, 2002).

Air and Noise Pollution Reduction

According to the United Nations Environment Program (2002), Melbourne was ranked among the worst communities by the amount of tropospheric ozone and the amount of airborne particulate matter. It is no doubt that the components of air pollution pose serious health risks to human life. For example, fine particulates from aerosols, smoke, dust, and fumes penetrate the respiratory system calling for medical attention. The study by Werthmann and Michael (2007) suggests that green roofs can remove upto 0.2kg of particulate matter per year across a square meter area of the roof. Research information also reveals that about 31% of the phosphorous source is airborne, therefore, green roofs have the potential to reduce phosphorous. Despite the fact that it is difficult to quantify the air improvement quality by green roof technology, the benefits suggest a better air quality evidenced by the reduced frequency of people seeking medical assistance in the respective areas.

The various layers used in developing a green roof significantly contribute to noise reduction. The Captains Flat (Abatement of Pollution) Agreement Act 1975, states that the soil used to construct green roofs absorbs common outdoor noise and the traffic noise too. This benefit is applicable to Robin’s Center that is close to a highway.

Heating and Cooling Mechanism for the building

Green roofs regulate the temperature of the building and, therefore, energy efficiency is achieved. Green roofs improve energy efficiency in a number of ways. First, the roof medium ensures a thermal break from the structural portion of the roof. More so, this thermal break is enhanced by the addition of the insulation layer as it is a requirement for constructing an extensive green roof. The second way through which green roofs improve energy efficiency is through the heat island effect; the vegetative layer gains less heat than the gravel surfaces.

Reducing the Urban Heat Island

On warm summer days in Australia, the air temperature in the suburbs of Melbourne can be several degrees higher than in the less urbanized areas; this phenomenon is known as the Urban Heat Island (Werthmann & Michael, 2007). The increased temperature is associated to the increased amount of roofing and paving, and a reduced size of vegetative cover that normally provide heat attenuation. The high temperatures result to an increase in the energy costs due to the demand for cooling equipment. Consequently, the rise in demand for hydropower increases air pollution through the burning of fuels. There is a scientific consensus that increased vegetation decreases air temperature. Green roofs have an overall impact of a vegetated urban surface, thus a decrease in the Urban Heat Island effect.

Extension of roof life span

The Australian climate cycles require that the infrastructure is designed and constructed with special consideration to temperature changes. Temperature variation affects exterior structures, buildings, sewers, and roadways among others (Graham, 2002). Foundations need frost protection because of latent differential movement of soils during freezing temperatures, therefore, structures should be designed to avoid temperature impacts and allow for expansion and contraction. In the Australian climate, materials expand and contract by up to 10% of their original sizes depending on the type of the material (Graham, 2002). Building roofs has dissimilar contraction and expansion coefficients to the adjoining rate of change. When traditional roofing materials are exposed to temperature changes over time, their elasticity reduces and consequently the roof gets torn. On the contrary, green roofs offer protection from solar radiation and other weather conditions, thus significantly reduce surface degradation and the expansion/contraction cycle. According to the study by Werthmann and Michael (2007), green roofs have the capability to extend the life expectancy of the traditional roofs by a factor of three.


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The Execution of a Green Roof Design. Analysis, Assessment, Concept and Design
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Marvin Namanda (Autor:in), 2015, The Execution of a Green Roof Design. Analysis, Assessment, Concept and Design, München, GRIN Verlag,


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