Green Roofs - Living Architecture Monitor - Winter 2009 - (Page 26)

RESEARCH TURNING YOUR BUILDING INTO A WATER SAVING “LIVING OASIS” AN INNOVATIVE APPROACH TO INTEGRATED BUILDING WATER MANAGEMENT By Alfredo Fernández-González he benefits of integrating living architecture into our cities continue to be well-documented and include protection of roof membranes from uv deterioration, slowing down stormwater runoff, reducing building heat gain, absorbing co2 through plant material and mitigating the urban heat island effect. In spite of these important benefits, however, the viability and future of many green roofs and walls is being challenged by the impending water crisis. Water reuse is recognized as safe, technically feasible and an increasingly cost-effective practice. To that end, this article makes the case for adoption of the “Living Oasis” concept, an integrated building water management approach – developed by industry expert volunteers on Green Roofs for Healthy Cities Integrated Building Water Management Committee – to significantly reduce the consumption of potable water in buildings, reduce discharge to the municipal sewer and save municipal energy by reducing the amount of potable water that needs to be pumped and wastewater that needs to be treated at a municipal facility. The severe drought experienced throughout the southeast of the United States in 2007 evidenced the vulnerability of many of our cities when it comes down to potable water supply. As cities continue to grow, so do their potable water demands while fresh water supply remains unchanged. For that reason, several regions around the country are already experiencing a decline in fresh-water supplies. For instance, droughts in the west are seriously affecting the Colorado River system which provides water to 25 million people in seven states (including cities such as Las Vegas, T Phoenix, Los Angeles and San Diego to name a few). In fact, according to a 2008 report by the Scripps Institution of Oceanography, that river system is not only operating at a deficit but there is a 50 percent chance that Lake Mead – the source of 90 percent of the water supplied to Las Vegas – could run completely dry by 2021. A 2003 report from the United States General Accounting Office forecasted that 36 u.s. states are likely to experience water shortages by 2013 (see Fig. 1 below). To make matters worse, the increasing demand for electricity is, in turn, also raising demand on diminishing fresh-water supply sources as approximately 97 percent of the electricity generated in the United States was produced by thermoelectric or hydroelectric power plants in 2006 – both of which evaporate considerable amounts of water as they generate FIGURE power (Energy Information Agency, 2007). The increased pressure to provide sufficient fresh water supplies for energy production, agricultural use and domestic consumption has also resulted in a strong interest in seawater desalination. According to the Pacific Institute, a think-tank focused on water issues, the world’s desalination capacity in 2005 was approximately 9.5 billion gallons per day; less than 2.4 percent of the total demand for fresh water in the United States. Aside from several serious environmental drawbacks, the desalination process requires more than 12.2 kWh per 1,000 gallons of fresh water supplied. The lack of national water policies in North America which balance human needs with the realities of the natural world has resulted in a wasteful use of water. When looking at buildings, potable water should only be used for drinking, cooking and human cleansing. Due to its strong level of purity, potable water has a high-embodied-energy content and is expensive to produce. Irrigation, makeup water for cooling towers and toilet flushing are examples of water uses that can be satisfied with non-potable water. While less pure, non-potable water that is properly handled can be used to reduce a building’s dependency on very precious potable water. An increasing number of buildings (or multiple-building developments) are harvesting and treating their wastewater onsite for later use in landscape irrigation, toilet flushing, and/or cooling-tower makeup. One of the first (and best) examples of this approach is the Solaire apartment building in New York City. A 28-story building with 293 dwelling units, the Solaire, EXTENT OF STATE SHORTAGES LIKELY OVER THE NEXT DECADE UNDER AVERAGE WATER CONDITIONS 26 LIVING ARCHITECTURE MONITOR WINTER

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Winter 2009

Green Roofs - Living Architecture Monitor - Winter 2009
Contents
From the Founder: When is a Green Roof Really "Green"?
Strata - People, Products & Projects: Funding for the Green Infrastructure Foundation (GIF)
An Integrated Approach to Green Roofs
On the Roof with...
Project: A Green Wall for Wildlife
Research: Green Roofs and Local Temperature
Turning Your Roof into a Water-Saving "Living Oasis"
Feature: Water & Georgia
GRHC Update: GHRC Professional Development Calendar
Accreditation Exam Subject to Stringent Standards
Welcome New Corporate Members
On Spec: Change We Can Believe In

Green Roofs - Living Architecture Monitor - Winter 2009