Autumn is great for residential construction, remodeling and retrofitting. With cooler breezes and regular family routines underway, September is an ideal time to get projects going before the long winter arrives.

Green building practices — which are characterized by efficiency, waste reduction and longevity — and sustainable design (the philosophy of meeting the needs of the present without compromising the needs of the future) are the hottest topics in the building world.

From siting to finishing touches, green building practices consider temperature, humidity and wind patterns; location factors — topography, vegetation, water resources, drainage patterns, etc.; and materials.

With the selection of building orientation, form, insulation (called the "envelope"), and other aspects, careful planning that incorporates a site's natural features into the design ensures energy efficiency (and therefore lowers heating and cooling costs), reduces water management woes (basement flooding and storm water deluges) and produces a home engineered to stand up to the elements.

For example, incorporating vegetation provides shade, buffers wind and helps manage storm water runoff. Siting a house to take advantage of natural wind patterns can save money on future summer cooling bills. Orienting a structure to best harness solar energy — rather than to capture a particular view — will lower a home's carbon footprint.

Many projects do not involve siting new construction, but rather working and maintaining the homes we already live in. Thus, green retrofitting is the emphasis, much of which focuses on materials selection. Green retrofitting and remodeling is about minimizing environmental impact as much as possible. It's matching structure and function to the local environment and climate in the least harmful manner, and it's making choices that weigh several factors, both technical and personal.

Since ALL materials pollute in some way, whether it's simply the fossil fuels burned in transport or the toxic byproducts produced during manufacturing, it could be most advantageous to use conventional materials such as poured concrete with Portland cement and iron rebar, but use them carefully and sparingly along with other lower-impact materials, such as salvaged concrete (also called "urbanite") and gravel-filling. Many contractors today are learning about green building or are becoming Leadership in Energy and Environmental Design (LEED)-certified and can address these topics during project planning.

There are also numerous Web sites, such as the U.S. Green Building Council's Green Building Links page at www.usgbc.org/DisplayPage.aspx?CMSPageID=76, which links to numerous resources on green building and materials. Also, the Council's Green Home Guide (www.greenhomeguide.org/guide_for_green_renovation/green_retrofit_checklist.html) has lot of information for homeowners interested in green retrofitting.

The following tips will get you started in understanding where you may green-up various aspects of residential structure. Part two addresses roofs, windows and doors, energy, water and waste management.

Siting

Siting is a complex task that requires some scientific knowledge about mapping solar angles, topography, hydrology, measuring wind and defining soil characteristics. Clarke Snell and Tim Callahan's book, "Building Green," has nearly 40 pages on the subject.

For recommendations, talk to builders and contractors about new homes, additions and solar and wind energy projects.

Foundations

Foundations are the cornerstone of sound structure. Low-load materials include fieldstone, urbanite, gravel, rammed-earth tires, and earth-filled bags. While iron rebar is 100% recycled, it requires a lot of energy to make, and should be used conservatively.

Many builders across the board believe you can't really get away from conventional concrete (containing Portland cement) due to its superior quality in eliminating leakage and its strength, though using it with other materials will reduce the amount you need, and therefore the impact on the environment (which includes air pollution in making and transporting it and urban overuse that results in the heat-island effect and energy spikes).

In the last few years, many products that contain concrete and insulation have emerged. Insulated concrete, which generally incorporates layers of plastic-based foam, are said to improve heat efficiency and reduce noise.

Additionally, there are efforts to mass produce magnesium carbonate cement (Portland is made from calcium carbonate), which is said to absorb carbon dioxide and in theory, reduce the greenhouse effect if it becomes as ubiquitous as the conventional variety. Some are advocating for concrete jungles of this type as a solution to global warming!

For more information about greener foundations, you may want to speak with a structural engineer that is LEED-certified. Your builder will likely have access to a person with this expertise, or have someone on staff.

Insulation

All manner of insulation are available for homes — in the basement, walls, roof and attic. Greenhomeguide.com has a great insulation buyer's guide comparing several varieties, including cellulose (sometimes called "straw bales"), cotton, fiberglass, polystyrene and others, and it lists the pros and cons (some have toxic qualities).

Insulation is one are where you can focus a lot of effort to go green, saving money and preventing additional toxics from entering your home and the environment.

Talk to local suppliers and look online to find out what's available in the area and ask which local contractors have purchased and installed the materials. When you speak to the contractors about your insulation project, ask for references especially if you are unfamiliar with the product you've selected.

Additionally, consider options like a radiant barrier on the underside of your roof. The aluminum facing sheets keep the attic, and whatever systems you may have in it, cooled off, which reduces cooling expenses and discourages mold build-up. Add a solar-power fan and you are really going to have the most energy-savvy attic on the block!

Walls

Ask big chain stores where materials originate from. Local, environmentally-superior materials are an ideal, and of course must be weighed against the sustainability needs of the project and energy efficiency criteria.

Wood from renewable forests shows great green commitment, but it may be more sustainable to consider local wood that is naturally resistant to termites and other pests. Vermiculite, a clay mineral, and earth-filled tires are other options that also help to insulate.

You might also try salvaging wood and other materials for some walls, or try cob (a natural building material similar to adobe) and/or cordwood (layers of short debarked log) construction techniques if a very natural-looking structure appeals to you. Cob is fireproof and holds up well with seismic movement.

Whatever you choose, buy materials conservatively and consult a professional on necessary quantities.

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Andrea Fox, a Beverly resident, has been writing about environmental sustainability and eco-topics for eight years. She is a member of the Society of Environmental Journalists and a watershed protection advocate in Salem Sound Watershed.