Fuel-efficient cars are nice, but most people spend their days in buildings, bathed in artificial light and breathing conditioned air. According to the EPA, buildings account for about 68 percent of U.S. electricity consumption, 39 percent of total energy use, and 38 percent of total carbon dioxide emissions.

Yet during the Age of Unlimited Energy, most homes, factories, and office complexes were constructed with energy efficiency and environmental impact as afterthoughts. Design was about aesthetics or up-front cost. Building placement was about curb appeal or logistics rather than the relationship to sun, wind, and shade. And when thought was given to energy efficiency, the result was often counterproductive, as when office buildings are sealed so tightly that their internal air becomes dirtier than that of the surrounding city. Most of today's buildings, in short, are energy hogs designed, built, and furnished in ways that are problematic for both their inhabitants and the environment.

But here again, that's about to change. As energy costs rise and more people figure out that livability is valuable, "green building" is suddenly in. And right on cue, technologies and techniques are being developed or resurrected that will make tomorrow's buildings not just energy efficient but, in some cases, energy negative, meaning that they will produce more energy than they consume.

Meanwhile, changes that make a building green frequently have benefits that go way beyond lower power bills. Houses with cleaner air and better light make for happier, healthier families. Schools with better ventilation and more comfortable temperatures report higher test scores. Green commercial buildings report fewer sick days, better worker productivity, and lower turnover. All of this translates into higher resale values and increased incentives to build green.

Defining Green Building

Standardizing and codifying green building is a lot harder than simply singing its praises. It's not immediately or intuitively obvious what a given attribute accomplishes and which, in a project with a limited budget, will give the biggest green bang for the buck. Are triple-glazed windows better than advanced lighting controls or superefficient insulation? How does nontoxic carpet stack up against a layer of sod on the roof? How much more can you charge (or should you be willing to pay) for a given basket of green upgrades?

In response, building organizations around the world have devised rankings and certifications aimed at standardizing their product. In the United States, the main certification is based on the Green Building Council's Leadership in Energy and Environmental Design (LEED) rating system. Building attributes are assigned points, and the points are added up to produce a LEED rating on a scale that runs from "Certified" through Silver, Gold, and Platinum.

Since energy efficiency is the main financial selling point of green building, let's start with a look at what buildings do with the electricity they consume. Something like half goes to motors that cool space and food and run industrial machinery. About a sixth goes to heating space and water. Lighting is 20 percent-25 percent if you include the heat given off by incandescent light bulbs that has to be air conditioned away. And myriad smaller categories like cooking and electronics use appreciable amounts of power. Each has massive room for improvement, and each interacts with some or all of the others. So taking a traditional building design and making it green is a complex puzzle with pieces that vary in size, price, and complexity. The art-and the investment opportunity-lies in combining them in effective, profitable ways.  ....read more