GREEN ROOFS & THEIR POTENTIAL Green Roofs and Walls and Sustainable Design Melbourne Forum 08 SIDONIE CARPENTER Green Roof & Living Wall Design Consultant President, Green Roofs Australia Inc. History of Green Roofs. Why Green Roofs? What is a Green Roof? Types of Green Roofs Benefits of Green Roofs Integrated design Green Walls GREEN ROOFS ARE NOT NEW Vikings built green roofs like this in northern Scotland in 895 AD. They were originally built for their insulative properties What is driving the Green Roof market? CLIMATE CHANGE & SUSTAINABLE DESIGN In the industrialized world 80% of the population now live in cities. (Binde,1998) Buildings and urbanization have created a unique set of environmental problems. Increased Carbon Dioxide levels Urban heat Island effect Reduced bio diversity Water management Many of these problems are either directly caused or exacerbated by the removal of vegetation to accommodate urban expansion. THE COST OF URBANISATION It is estimated that the construction, operation, maintenance and demolition of buildings contributes up to 40% of global greenhouse gas emissions (UN SBCI 2006). We need to be actively changing & incorporating sustainable practices into our construction industries. WHY GREEN ROOFS & WALLS? Modern architecture leaves less available green space and this is one way of reclaiming it & integrating it into building design. Green Roofs & Walls make a unique contribution to the quality of our urban environment. As we move into the 21 st century, green roofs & walls can address many of the challenges presented by urbanization & climate change. Musee du quai Branly Paris
WHAT IS A GREEN ROOF? TYPES OF GREEN ROOFS A green roof is created by adding layers of growing medium and plants on top of a traditional roofing system. Green Roofs convert wasted roof area into viable and valuable green space for public & private benefit. There are 2 types of green roof Intensive Extensive The two systems are differentiated by cost depth of growing medium choice of plants Singapore Botanic Gardens visitors center EXTENSIVE GREEN ROOFS light weight 300mm or less growing medium low capital cost low plant diversity minimal maintenance requirements INTENSIVE GREEN ROOFS deeper soil and greater weight, > 300mm deep higher capital costs increased plant diversity more maintenance requirements GREEN BUILDINGS & GREEN ROOFS Consume less energy & water Healthy & productive environments public & private benefits. Maintain & enhance bio diversity Do not pollute, in fact they clean noise, water, air They Work research of real benefits Brits Pub bowling green, Minneapolis SELLING THE CONCEPT Green Roofs generate - social, economic and environmental benefits, both public and private. Each green roof installation is unique. Key to success is finding the right mix of benefits for a particular client and for their project. Toronto MEC store
BENEFITS ENERGY SAVINGS - Green roofs shade the building from solar radiation. ROOF MEMBRANE PROTECTION - European evidence indicates that green roofs will easily double the life span of a conventional roof. SOUND INSULATION - 12 cm of growing medium alone can reduce sound by 40 db. URBAN HEAT ISLAND EFFECT when 8% of a cities roofs are green the ambient temperature can be reduced by 2 degrees C. STORM WATER RETENTION & MANAGEMENT AIR CLEANING - filter out fine, airborne particulates. BIO DIVERSITY replacing lost habitat. ENERGY SAVINGS Green roofs shade the building from solar radiation Reducing, if not eliminating any net heat gain. Decreasing the amount of energy required to cool the building. The extent of the energy cost savings impact is a function of: the size of the building, its location, the depth of the growing medium, and the type of plants and other variables. NY Rockefeller Center - SOUND INSULATION growing medium blocks lower frequencies plants block the higher frequencies. Tests show that 12 cm of growing medium alone can reduce sound by 40 db. - Schiphol Airport, Amsterdam. URBAN HEAT ISLAND EFFECT The overheating of urban areas, due to increased paved, built-over, and hard surface areas. High summer temperatures have a range of direct and indirect negative impacts on our quality of life. The urban heat island effect increases the use of more electricity for air conditioners and it increases the rate at which chemical processes generate pollutants. A city can reduce ambient temperature 2 degrees C when only 8% is green roofs - Chicago and Prague Research and Data International quantitative data. Onmura et al. (2001) field measurement, planted roof in Japan. The evaporative cooling effect of a rooftop lawn garden showed a 50% reduction in heat flux in the rooms below the garden. And a reduction in surface temperature from 60 to 30oC during the day. Niachou et al. (2001) measurement of surface and air temperature on a planted roof. The work was further complemented by a mathematical approach through which thermal properties of green roofs and energy savings were determined Wong et al. (2003) and Kohler et al. (2002), have shown that under a green roof, indoor temperatures were found to be at least 3 to 4oC lower than outside temperatures of 25 to 30oC. Liu and Baskaran (2003) report that field research - energy required for space conditioning due to the heat flow through the green roof was reduced by more than 75%. An energy reduction from 6.0 to 7.5 kwh/day for cooling was demonstrated Alcazar and Bass, (2005) the installation of a green roof in Madrid reduced total energy consumption by 1% with 0.5% reduction in the heating season & a 6% reduction in the cooling season. STORM WATER RETENTION Water is stored in the growing media, drainage cell & plants, and slowly released over time. Filter contaminants from rainwater Oregon found that if 219 acres (1/2 the city buildings) had green roofs, an estimated 250 million litres of water would be retained annually.
AIR CLEANING Green roofs filter out fine, airborne particulate matter as the air passes over the plants. Airborne particulates tend to get trapped in the surface areas of the greenery. Rain washes it into the growing medium below. CREATION OF HABITAT Provision of wildlife habitat Replacement of lost habitat Provision of links or stepping stones for wildlife Providing outdoor classrooms in urban areas. ADDITIONAL BENEFITS Accessible green roofs providing added amenity space for the occupants. Food production Increased marketability & property value Planning approval & green building star rating. Government rebates. INTERGRATED DESIGN Few technologies have ever had so much to offer by way of improving the health and well being of urban residents, while contributing to the development of restorative, high performance buildings. The integration of green roof technology with: solar panels for increased energy yield. grey water recycling. condensate from air conditioners, or cooling tower water for irrigation. ARE GREEN ROOFS COST EFFECTIVE? The additional cost generally relates directly to the increased load on the structure. A Green Roof may cost 1/3 more, however when you take into consideration Energy savings Roof lifespan Calculated over the lifespan of a green roof, the cost may only be ½ of a conventional roof. A recent study of 33 of the greenest buildings in the US found that average cost premium of building green was 1.63% GREEN WALLS Green Walls refers to the planting of vertical surfaces. Both internally and externally. They are a key part of the global movement towards sustainable integration of the built and natural environments Qantas Lounge - Melbourne
l INTERNATIONAL EXAMPLES The Germany Green Roof industry annual growth rate is 15-20%, 1989-1 million m2 of green roofs were installed 1997-11 million m2 2001-13.5 million m2 (Thompson & Sorvig 2000). Several cities have incorporated roof greening into their building regulations. Over 75 European municipalities currently provide incentives or requirements for green roof installation. A key motivator for this support has been the public benefits of Storm water runoff reduction & management. Air and water quality improvements. Energy savings. As a result, a new sector in the construction industry has been created, and green roofs have become a common feature in the urban landscape. Stuttgart & Berlin Germany Ford Motor Plant Michigan If we can make our cities healthier, they will become places where people will want to live, play, and work and economic growth will follow naturally. "green roofs are the greenest thing one can do in construction except not to build at all. -Architect Patrick Carey The biggest green roof in the world - 10.4 acres Helped save the adjacent Rouge River, 50 years ago faced environmental disaster due to toxic chemicals leaking into it from the factory. Apple concept store - Chicago Peggy Notebart Museum - Chicago
New York Silver Cup Studios Brooklyn Botanic Gardens Academy of Science San Francisco Renzo Piano & William McDonough Millennium Park - Chicago School of Art & Design Nanyang Tech. University, Singapore Green design need not hinder economic development. Beauty and sustainable design can inspire creative and forward thinking developers who might actually drive further competition. AUSTRALIAN EXAMPLES Sydney Conservatorium of music Finger Wharfs
M Central Sydney 360 Landscape Design AUSTRALIAN OPPORTUNITY The prospect of an entirely new horticulture-based industry in Australia deserves consideration as an economic offset to the inevitable costs of countering climate change as well as a way to cool and beautify the urban landscape. This will generate new careers and new business for urban planners, architects, landscape architects, horticulturalists and landscape contractors, builders, roofers, developers, and building owners, as well built-environment regulators, researchers and academics. GREEN ROOFS AUSTRALIA A not-for-profit membership organisation with an elected committee that draws together the various governmental, organisational and business groups and individuals interested in being kept informed about green roof science, technology, practice, regulations and specifications. We promote green roofs as an effective response to climate change and city heat island effects, and to reduce buildings carbon footprints. www.greenroofs.wordpress.com "My interest is in the future because. I am going to spend the rest of my life there." - Charles F. Kettering SIDONIE CARPENTER GREEN ROOF & LIVING WALL DESIGN CONSULTANT GREEN ROOFS AUSTRALIA www.greenroofs.wordpress.com