Water Water Everywhere
The Western World’s practice of using huge amounts of drinking-quality water to transport sewage is unsustainable.This is increasingly evident as the population grows in the dry regions of the United States. Plumbing fixtures that use little water or no water are available from various manufacturers.
They include composting toilets, waterless urinals, low-flow toilets(various models using 1.6 gallons per flush or less, including standard gravity-flush and pressure-assist models),low-flow showerheads (various models using less than 2.5 gallons per minute), low-flow faucets (using less than 2.5 gallons per minute), metered faucets (to ensure that faucets in public bathrooms will not be left on),and shut-off valves for kitchen faucets and showerheads that enable the temperature setting to be “saved” while the water is temporarily shut off.
Treating graywater from showers, sinks, washing machines, and other appliances as if it were blackwater from toilets and garbage disposals is not the most efficient strategy.
Graywater can often be reused directly for toilet flushing or subsurface irrigation depending on regional codes. Graywater can also be used on [non-edible] plants after treatment with a commercial filter or site-built sand filter. Gray water waste-heat recovery systems can capture the heat from showers or other fixtures as it goes down the drain and transfer that heat to incoming water. These systems are especially effective in high use shower areas, like locker rooms.
Capturing rainwater for irrigation greatly reduces the demand for treated water, and collected rainwater—oxygenated, non-mineralized, and non chlorinated—is much better for plants.Rainwater can also be used around the house, even as drinking water.
Typically a building’s roof and gutters can double as its rainwater collection device. For potable water collection, it is critical that the roofing not leach lead, copper, asbestos, petrochemicals, or other nasty things. Modern steel roofing is likely to be the safest option as long as the coating doesn’t contain heavy metals: old metal roofs with toxic coatings and lead fastening systems should never be used to collect drinking water. Cisterns for rainwater storage can be made out of metal, concrete, or plastic. The first step in water treatment is to remove large pieces of debris with gutter screens and roof washers; sediment can be allowed to settle within the tank or it can be removed with cartridge filters.
If disinfection is needed to ensure human potability, the options include chlorine, iodine, ultraviolet light, and—more expensively—ozonation.
Light and Heat
Even in mild climates, the sun can cause roofs to reach extremely high temperatures. A reflective roof will stay significantly cooler, last longer (by reducing heat and UV damage), and reduce heat-island effects. Multiple studies of buildings in hot climates(e.g., in California, Texas, and Florida)have documented ten to fifty percent energy savings when roofs were painted with reflective coatings. Reflective coatings can bounce away as much as eighty-two percent of total sunlight; non-petroleum water-based reflective coatings are best. Green roofs (built with soil and native plants, and mimicking natural topography) UV-protect the roof membrane while providing habitat for flora and fauna, insulation, storm water management, clean air, and natural beauty—excellent for habitable roofs or roofs visible from above.
If renewable energy is a priority, the marginal costs of upgrading to PV-integrated roofing panels or PV shingles when installing a new roof or replacing an old one should be considered, because this will be cheaper than installing stand-alone PV panels in addition to a roof.
With thousands of door and window products on the market, selecting the right ones might seem like a daunting task.
Your goal when selecting windows is to specify a product that has the climatically appropriate insulating value, lets in a high percentage of visible light for daylighting, and provides the appropriate solar heat gain coefficient (SHGC). Because there are many options and manufacturers, it is possible nowadays to “tune” glazing for specific orientations and conditions. The best windows can be essentially perfect in letting in light without heat.
In the coldest climates you’ll want “low-e” windows that also offer high visible light transmittance, insulating gas fill (argon or preferably krypton), good edge seals, insulated frames (with thermal breaks if frames are metal), and airtight construction.Instead of applying low-e coatings directly to glass, several window manufacturers apply it to a suspended plastic film between the panes of glass. Triple-pane windows are also an option, although they’re heavier and costlier.
Several new glazing products may become common in the future. One is a gel, inserted between glazing layers, that turns from clear to reflective white when exposed to a preset amount of heat, sunlight, or electric current. This gel can be used in skylights to provide full daylighting on cloudy days while avoiding glare and overheating on hot sunny days (in its light-blocking white form, it still admits ten percent of incident solar energy—potentially enough for glare free daylighting). Another product that could become revolutionary for window technology is Aerogel, a silicon solid (the world’s lightest—like “solidified smoke”) that transmits over seventy percent of visible light but blocks heat three to four times better than common insulation products like rigid foam and fiberglass.Aerogel was developed in the 1930s and used by NASA for space exploration, but could have many building applications.
Insulation is important to keep heat in or out, depending on the climate.There are many considerations when choosing an insulation material.When researching insulation types and brands, ask yourself the following questions: Which type will provide the best R-value within a reasonable thickness? Does it allow airflow? As with other building materials, will it release gaseous pollutants into the building interior? Will it pose potential health risks to installers or manufacturers, and if so, can precautions be taken to prevent these risks?Finally, does the insulation contain ozone-depleting chemicals?
These are only a few of the considerations you’ll need to evaluate in your green building. Thinking about them should spark ideas in other aspects of design and construction. Most important, they should be considered as part of a whole system. For instance, the amount of shading that the landscaping around a building provides will have implications for the type of glazing needed; both landscaping and glazing will affect the heating and cooling requirements; if rainwater is to be captured for drinking, only certain roofing materials should be used. All these issues are interconnected. Besides approaching green building as a whole system, remember also to question the status quo and to think creatively.
ADDITIONAL REFERENCES FOR WINDOW INFORMATION:
• National Fenestration Rating Council www.nfrc.org
• Efficient Windows Collaborative www.efficientwindows.org
• Glazing Design Handbook (1997), AIA
• LBNL—Window Technology http://windows.lbl.gov/technology/highly_insulating.htm
• Selecting Windows for Energy Efficiency (512 KB)http://windows.lbl.gov/pub/selectingwindows/window.pdf
As with many products, it is worthwhile to ask window manufacturers whether their products contain recycled materials. Even if the manufacturer does not use recycled content, knowing that customers are requesting it helps to move the marketplace toward recycled products.
Copyright 2012 Ronald Sauve All Rights Reserved
This page was last modified on April 06, 2012
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