Green roofs - future of urban life

Jure Šumi

Green RoofsGreen roofs as old as „Hanging Gardens of Babylon“

In modern times, Germany was the first to start with green roofs about 50 years ago.

Types of green roofs

Why green roofs

• Energy Efficiency – green roofs reduce the energy consumption:– Up to 25% for heating*

– Up to 75% for cooling*

– Collective positive effect in „Central Europe-alike“ climate zones averages 7kWh per sqm/year (considering already pre-insulated roofs)

• Lower Urban Heat Island Effect

The infra–red image shows that on a typical day, the Chicago City Hall green roof measures almost 80°F (40°C) cooler than the neighbouring conventional roof

Temperature differences between a Green and Conventional Roof **

Main positive effects of green roofs

* National Research Council of Canada** national center of excellence/ASU

• Significant impact on CO2 emissions– 1 sqm of lawn can absorb 5 kg of

CO2/year

– Reduction of energy use also has its impact on carbon dioxide reduction (3,2kg CO2/sqm per year)*

– To give a perspective – 1 sqm of green roof can absorb as much of CO2 as one car produces when driving from Zagreb to Varaždin (cca 80 km).

• Cut back on the amount of dust and other pollutants in the air – 1 sqm of green roof remove 0.2 kg of

airborne particulate from the air every year**.

• Better storm water management– In some countries (Germany.

USA,..) owners of buildings can reduce their municipality taxes related to storm water management up to 50% simply buy setting up green roofs .

• Increased Roofing Membrane Durability

- Double life time of roof surfaces

• Increased Biodiversity

• Positive impact on people

* National Research Council of Canada** national center of excellence/ASU

Main positive effects of green roofs

Standard basic components / layers:

• Vegetation

• Growing media

• Filter membrane

• Drainage

• Root barrier

• Waterproofing

Traditional extensive green roof systems

Variable water absorption capacity– many substrates have low water absorption rate

when totally dried out

Heavy – soil substrates have density 900– 1200 kg/m3– suitable thickness to provide enough water

storage is between 8 - 10 cm

Labour intensive – to work on 1.000 sqm green roof means moving

cca. 100 tons of soil substrate on the roof to make a proper ground for vegetation

Costly – it takes time and extensive man and machine

power to make it done

Main pitfalls of traditional systems

What to change?It is all about substrate and its quality & performance!

Good substrate:• is light weighted• has high constant high water absorption rate• provides long-term water retention stability• offers good thermal insulation property and• is easy to install.

Needled rock mineral wool fibres combined with superabsorbent polymers

Substrate typeTotal Water

Holding Capacity(% of volume of substrate)

Substrate weight

10 cm deep

Water Holding Capacity

10 cm deep Sandy soils 10 - 20 110-120 10 - 20Loamy soils 20 - 30 120 - 130 20 - 30Clay soils 30 - 44 130 - 150 30 - 44Green roof substrates up to 35 80 - 100 up to 35Needled felt (110 kg/m3) 77 11 77Needled felt with polymer up to 90 11,1 up to 90

Advantages of Urbanscape extensive green roof systemHigh and constant water absorption rate with long-term water retention stability- Suitable thickness to provide enough water

storage is between 2 and 4 cm

Lightness – Urbanscape substrate density is 110 kg/m3

which allows to build green roofs also on buildings where existing systems cannot be successfully implemented.

Low labour intensity– to work on 1.000 sqm green roof means

moving between 2 - 4 tons of Urbanscape substrate on the roof

Low cost installation – due to easy set-up process up to 30%

lower cost for installation

The new world of new applications to tackle

Urbanscape roof vegetable gardens

Landscaping applications

Slope greening

Gardens, Parks, Graveyards

Agriculture in dry areas

Simple system

Urbanscape in-house gardens

Q & A