Organic Greenroof Architecture: Sustainable Design for the New Millennium (1)

Making the most of your building's "fifth façade"

© Wiley Periodicals, Inc.

Environmental Quality Management/Summer 2005

By Linda S. Velazquez

High-performance buildings, green design practices, and sustainable

technologies are becoming increasingly important influences on architectural

practices around the world. They are even beginning to influence standards

within the construction industry.

Encouraged by growing interest and demand on the part of both the public

and private sectors, multidisciplinary professionals -- from architects to

environmental managers, from engineers to landscape architects and beyond --

are redefining the way we look at design and examining our environmental

impacts on the Earth with an integrated, holistic approach.

Green Building. Green Architecture. Green Roofs.

“Green” anything nowadays is a hot topic and a buzzword -- sometimes

wholeheartedly embraced, other times politically charged, sometimes even

scoffed at. But perhaps this design adjective should be accepted simply as a

common-sense approach and an indication of respect for both our natural and

built environments.

But what constitutes "building green," and what does sustainability mean

in the context of building design? In the United States, the Office of the Federal

Environmental Executive defines green building as "the practice of (1) increasing

the efficiency with which buildings and their sites use energy, water, and

materials, and (2) reducing building impacts on human health and the

environment, through better siting, design, construction, operation, maintenance,

and removal -- the complete building life cycle.

The simplest definition of sustainability is design that meets the needs of

the present generation without compromising the ability of future generations to

meet their needs.

Noted green architect William McDonough asks us to imagine building

structures that not only do not hurt the environment, but that contribute positively

to ecosystems, and possibly even help heal disturbed landscapes.

About this Article

This article presents an overview of the greenroof concept. Included is

discussion of the history of greenroofs -- which, though relatively modern in their

present form, are rooted in ancient vernacular architecture and in the innate

human desire to connect the built environment with nature.

I discuss basic greenroof technologies, and explain some of the key

ecological, economic, aesthetic, and psychological advantages that greenroofs

offer to both users and owners.2

Global Concerns Drive the Search for Green Solutions

Several issues of global environmental concern have been driving a new

"greater green." Factors such as global warming, air and water pollution,

population growth, and loss of habitat and biodiversity have contributed to the

call for improved environmental design.

In a 2001 "Special Report on Global Warming," Time magazine noted that

the global mean temperature is expected to rise between 2.5ºF and 10.4ºF over

the next 100 years. The United Nations weather agency recently stated that

Earth's average temperature in 2001 was the second highest recorded since

global records began 140 years ago.

The Kyoto Protocol, which is aimed at slowing global warming by reducing

human impacts, went into effect in February 2005. The Protocol commits 35

industrialized countries -- the U.S. not among them -- to reducing their emissions

of six greenhouse gases (principally carbon dioxide) to five percent below 1990

levels by 2012.

Some other indicators of environmental stress include the following:

· The U.S. Census Bureau reports that at midyear 2002, the global

population reached 6.2 billion. The United States alone will be home to

420 million people by 2050, or 140 million more than in 2000.3

· Humans now consume natural resources 20 percent faster than nature

can renew them.

· Use of fossil fuels increased by almost 700 percent between 1961 and

2001.

· Populations of land, freshwater, and marine species fell on average by 40

percent between 1970 and 2000.4

· Impervious cover has become a signature effect of contemporary land use.

Our paving of open land and speculative development patterns resemble

an urban equivalent of the “slash and burn” clear-cutting techniques that

are still so prevalent in forestry and agriculture.

· As a result of our land use practices, we have developed over-stressed

sewer systems and urgent stormwater management problems.

In an era when developing clean and renewable energy strategies and

addressing ever-increasing energy consumption rates are so crucial to our

economic and ecological future, it is clear that we need to fully examine ecofriendly

alternatives that also make economic sense in order to truly create a

sustainable world.

Global Answers Include Sustainable Greenroof Architecture

Greenroofs are not a panacea for our environmental construction ills. Nor

should any one single design component carry that burden. The beauty and

promise of sustainable architecture and design lie in the integration of roof,

building skin, interior, site location, and overall building design.

But viewed as one layer of a green building strategy, greenroofs can play

an important role. They can:

· reduce ambient air temperature, energy use, and utility costs;

· help cleanse the air and water;

· utilize local and recycled materials;

· extend the life of the roof;

· improve aesthetics; and

· create greenspace for humans and wildlife while providing a psychological

and physical respite from urban surroundings.

What Is a Greenroof?

What exactly constitutes a greenroof? Greenroofs are simply vegetated

roof covers constructed atop and across a roof deck. They sometimes are called

ecoroofs, sky gardens, even skyrise gardens. As living roofs, they contrast

starkly with the average inert, hot, barren roof.

The use of greenroofs on commercial buildings can help further the goal of

maximizing the eco-friendliness of the built environment.