Green Terminology 101
There are a lot of terms and phrases that get thrown around when it comes to green remodeling and building. Not understanding the basic concepts can make it difficult to follow the discussion. Here are a few of the common words and ideas you should understand: GREEN is a buzz word, no doubt about it.
There are a lot of terms and phrases that get thrown around when it comes to green remodeling and building. Not understanding the basic concepts can make it difficult to follow the discussion. Here are a few of the common words and ideas you should understand:
GREEN is a buzz word, no doubt about it. But underneath the warp of marketing, there is meaning that endures — and matures. Initially, green building meant "less taxing on Earth's resources." Today, it's about state-of-the-art construction or best practices; installing particleboard cabinets that off gas is not state-of-the-art or green. Plunking solar panels on a roof, while failing to orient for passive heat gain, misses the green mark of excellence.
Many building products and furnishings release or OFF-GAS chemicals. Volatile organic compounds (VOCs) become gaseous under atmospheric conditions. Despite their bad rap, not all VOCs are hazardous to health. Meanwhile, other chemicals, such as formaldehyde, methyl chloride, and chlorinated organic compounds, are not technically VOCs but still have potentially serious health consequences.
CERTIFICATION is an independent, third-party process for establishing the greenness of projects (NAHB's National Green Building Standard), of professionals (NARI's Green Certified Professional, NAHB's Certified Green Professional), of products (EPA's Energy Star), and of product source (Forest Stewardship Council).
EMBODIED ENERGY refers to the upfront or fixed energy cost of building a house as opposed to the energy cost of operating it. For example, a home built of adobe bricks made on-site and fired in the sun has a very low embodied energy cost. Calculating embodied energy is a tough task. The process begins by estimating the energy used in mining, harvesting, and transporting raw materials; manufacturing a product; and shipping it to market. The end point disappears on the horizon. It includes the energy cost of getting the product to a construction site; moving laborers to and from the site, operating machinery and tools on site; plus a pro-rata percentage of all the energy invested in manufacturing the equipment used in each step of the process.
The energy intensity of a material or product is highly correlated to its CARBON FOOTPRINT. That's because burning fuel to operate electrical plants and to power machinery and transportation generates gases that cause a warming or greenhouse effect. Today, carbon dioxide stands as the proxy for all greenhouses gases. The smaller the carbon footprint of a person or building, the lower the impact on climate change. In theory, one can take actions to neutralize a carbon footprint. By fully offsetting a carbon footprint, a person or project becomes CARBON-NEUTRAL.
ZERO ENERGY means that a building exports as much or more energy via grid-connected photovoltaic or wind systems than it takes in gas and electricity to operate it. (Embodied energy is not factored into the equation.) Conservation through passive design and a tight building envelope are the cornerstones of a zero-energy home.
Conventional and solar heating systems are called ACTIVE because they use mechanical, moving parts to collect heat from air, the ground or a fluid and convert it into a desirable thermostat setting. A conventional HVAC system represents a modest amount of embodied energy but uses a lot of energy in the operating mode. An active solar heating system has a higher quotient of embodied energy but requires less operating energy.
PASSIVE SOLAR is a completely different building construct based on adapting the building to the climate through thoughtful design. Houses capture solar heat in winter through proper orientation but bar it in summer with deep eaves. Natural lighting replaces light fixtures. Tight building envelopes minimize the need for supplemental heating and cooling. If well-designed, a passive home will have less embodied energy than a conventional house with minimal energy use for climate control. (There are also passive solar hot water systems.)
LIFE CYCLE COSTING is an engineering practice of estimating the total financial cost of constructing, operating and maintaining a building over its life cycle. In short, durable buildings that minimize energy and water use will achieve a better LCC than others. Direct costs are relatively straightfoward. The problem is identifying and quantifying indirect costs (e.g. the impact of a reflective building on it's urban environment) and benefits (e.g. higher employee productivity due to natural lighting).
A LIFE CYCLE ASSESSMENT quantifies the environmental, rather than financial, impact of a material, product or building. The scope of an assessment is CRADLE-TO-GRAVE or CRADLE-TO-CRADLE, if components are reusable or recyclable. The goal is to, first, identify all the energy, water and materials that flow in and out of each lifecycle stage and, second, to assess the impact of those flows on humans, other species and our shared habitat.
If you have ideas or comments, e-mail [email protected]