It is fairly common now to hear the term green home, especially when dealing with newly-constructed houses. While there is not enough space here to go into the details, this article is meant to be a summary of the topic.
LEED for Homes
LEED means Leadership in Energy and Environmental Design and it refers to residential properties that meet certain specific criteria relative to:
(1) the site itself on which the building is built;
(2) the location of the structure relative to shopping, schools, parks, and so forth (called linkages;
(3) water efficiency (both in the structure and on the site);
(4) energy and atmosphere;
(5) awareness and education;
(6) materials and resources (what the house is built of); and
(7) indoor environmental quality.
A Sustainable Site
One example of a sustainable site is one, for example, that does not require the destruction of wetlands or removal of threatened or endangered native animal and/or plant species from their habitat(s). In other words, a sustainable site is one that already exists, preferably in an area that already has a relatively dense land use zoning classification. This is in an attempt to prevent moreurban sprawl. It also refers to sites that were, at one time, landfills and are now reclaimed for other uses. It also refers to razing older homes and, in effect, recycling the site. It also refers to sites that are as small as possible (see water efficiency, below.
Locations & Linkages
Developers construct LEED housing or green housing close to existing facilities such as schools, parks, houses of worship, entertainment, and so forth. In the real estate business these are called linkages. This, too, is thought to prevent urban sprawl and make more efficient use of existing urban and suburban infrastructure.
Water Efficiency
Other than to look pretty, lawns have no real purpose and suck up a great deal of water, which then cannot be put to another use. Thus an LEED house sits on a relatively small site and lawn is kept to a minimum. The landscaping present consists mainly of hardy plants, native to the local environment, preferably those that can survive with a minimum of water and husbandry. Then, the house's grey water (i.e., the non-sewerage waste water) stays on site and functions to water the landscaping.
In the house itself, the toilets are low-flush meaning they use only about one to one and one-half quarts of water per flush, or about half of what older model toilets used. There are even houses withchemical toilets using no water at all. However, this requires what amounts to a storage tank to hold the liquid chemicals and waste, which must be pumped out periodically. Potable water coming in the house passes thru a filter (carbon or reverse-osmosis) to remove any organic contaminants.
Instead of one large hot water heater (60- to 80-gallons), there may be three or four smallerheaters, all of which are heavily insulated. They are very close to the appliance they serve to minimize heat loss in the pipes from the heater to the appliance. Even better, the hot water comes from a solar heating system and/or gets it heat from the the exhaust of the central-HVAC system.
The house's grey water (see above) is part of the site's irrigation system. The irrigation system itself does not relay on the wide-broadcast of a fine mist of water, since this can evaporate too quickly. Rather, its uses a drip system so that each plant receives a constant drip of this water directly at the plant's stem where it comes out of the ground. The drip system does not work on lawn; but remember, there is no lawn in green construction.
Energy and Atmosphere
While wind-power is not really a viable option for most home owners, solar power and HVAC-exhaust are (see above). LEED houses will stay attached to the local electrical grid, but the these houses use the electricity more efficiently (for the above reasons). Use of solar power means all the house's hot water comes from non-electrical sources, thus result in a decreased use of fossil-fuels. The same is true of using the HVAC's exhaust to heat water. There will be net energy savings if builders and homeowners use this wasted resource as an alternative source of energy to heat water.
Awareness and Education
Architects and structural engineers now study green construction methods as part of their college training, both under-graduate and post-graduate. Many states are incorporating green construction methods into the classes applicants must take to be either residential- or general-contractors, and make it a part of the continuing education curriculum, as well. Real estate brokers and appraisers have been introduced to green construction concepts from a standpoint of how to use them to "sell" houses, as well as in the appraisal of houses and commercial buildings. More on this latter topic later, however.
Another area of >i>awareness and education is that of the use of recycled and recyclable building materials as part of green construction. As merely one example of this, consider bio-based spray foam insulation. Currently one of the more popular bio-based spray foam insulation is made from soy-bean oil. When the contractor sprays this material into place it looks and acts much like mousse for your hair. It significantly increases its volume by absorbing air. And air bubbles are great insulators.
Because the contractor applies it as a liquid, it flows into the tiniest crevasses and recesses in walls, around electrical outlets, window frames, etc (unlike fiberglass insulation). It then hardens as it expands, meaning it will stay in place (unlike blown rock-wool insulation). Since it is soy-based, it is from a renewable source, contains no noxious chemicals, is easy to install and requires no maintenance. Even though it comes from an organic source, bugs won't eat it. It does not lose its insulating volume if it gets wet and, once dry after its initial insulation, is not water soluble.
Materials and Resources
One example of green building materials is the bio-based spray foam insulation. Another important construction material innovation that is an example of using recycled materials is that of roofing tiles. Traditionally these have been made of wood, concrete, or asbestos. However, green construction now has the ability to use shingles made from recycled car- and truck-tires, as well as all types of plastic bottles. Whereas traditional cedar-shake roof shingles were rated for 10- to 20-years (depending on climate and maintenance), those made of tires or plastic bottles have a 50-year rating and essentially no maintenance. When these are properly applied they will withstand sustained winds of up to 110 miles per hour (and can be made stronger where building codes demand higher wind ratings).
And Finally Indoor Environmental Quality
Remember that "new car" smell we all like so much? Or how about the smell of a freshly painted room? Well, they are about to be a thing of the past (in many - but not all - cases). These smells come from what those who study such phenomena call volatile organic compounds or VOCs. In these cases "volatile" refers to how easily they escape from their base compound(s) into the air. Since they are noxious to us, we human beings are best off not smelling them (despite the nostalgia with which we may hold the "new car smell"). If VOCs are present then the indoor environmental quality is poor. Green building materials are low-VOC, thus don't smell "new" for very long.
Some green building materials, such as the soy-based insulation (above), while not specifically fungicidal, do not foment the growth of mold and mildew as can more traditional building materials. With a heavily insulated green home, in certain climates, it is possible to install more or larger windows to allow in more ambient light than otherwise would be the case. The theory is that this permits the green home to use less electricity since there will be less need to illuminate the house's interior.
Is There a Downside to Any of This?
There surely is. In the past green construction was much more expensive, both from a standpoint of the labor involved as well as the materials themselves. However, costs have come down as more developers and builders have become more comfortable with the uses of green materials. Many builders, developers, and real estate brokers will swear that a green home has a higher resale value than a similar property more traditionally built. Unfortunately there are no properly assembled Country-wide statistical data to support this claim. Further, by making this claim, builders, developers, and real estate brokers are basically saying that any green-building savings that will accrue to second and subsequent homeowners is lost in the premium those buyers will pay for the green-built house. Therefore, the claim of cost savings not only currently lacks statistical support in the market, the logic behind the claim of savings is not logical.
Another downside is the use of the organic materials themselves. For example, the use of soy-based products. Those who grow soy beans do not care what the buyers of the beans do with them. However, if a portion of the beans are shifted from consumption as food to consumption as something else, then some fallow land must be shifted into production to make up for the soy beans that are going to insulate your house, not go on your plate. Now more land must be used to grow soy beans for food consumption than was necessary before. Since mass agriculture can't yet take place organically, this land needs petroleum-based fertilizer and -pesticides to grow the soybeans that before it was not necessary to grow. As a result, the net benefit to the environment is questionable, at best.
Finally, green building is not any less expensive than are current building methods. The use of renewable building materials is not a new idea - trees are a renewable resource and we have been using trees as part of construction of literally hundreds of years.
Conclusions
While so-called green construction clearly has many benefits to those who build and those who consume homes, price savings is not yet one of them. The fact that many of these green building materials are organic in origin indeed makes them renewable. However, those renewable crops require petroleum-based fertilizers and pesticides to make growing them economically feasible. Therefore it appears that, on balance, green housing is not yet the panacea to the planet some would have us think
