As the housing market continues its path to recovery, certain mistakes when using engineered wood products (EWP) are becoming more common.
Mainstreaming Green Building
There are two common reasons the majority home builders' offer for not embracing green building and sustainable design: They don't want to throw out everything they know and re-learn how to build green houses. It costs too much to build green houses.
There are two common reasons the majority home builders’ offer for not embracing green building and sustainable design:
They don’t want to throw out everything they know and re-learn how to build green houses. It costs too much to build green houses.
|Being a green builder isn’t only about the homes built. It also must mean managing--and reducing--the amount of waste on each job. This means getting your subs committed and involved to reducing waste as well. The following message created for Austin’s green builder program sets the right tone. Construction Waste Management and Recycling
It is important to the Owner, and for the sake of our environment, that construction waste on this project be handled responsibly by the General Contractor and all subcontractors. A few simple steps will make a big difference. Let’s all make a sincere effort to do our part.
Minimize jobsite waste by using resources wisely. Framers are encouraged to consider their lumber cuts carefully, and follow the optimum value engineering construction details and techniques provided in the plans. This will save trees, and construction costs if enthusiastically embraced. Scrap gypboard can be used for smaller wall areas and as a backed board to protect waterproofing prior to backfill.
Separate waste to facilitate recycling. Set up areas on the jobsite to deposit wood scraps, mixed metals, cardboard and gypboard. Keep pressure treated wood, dimensional lumber and sheet goods in distinct piles for future use on the project. Remember that pressure treated wood is toxic and can contaminate soil and water--use wisely and sparingly.
Recycle. Consider donating remaining useful lumber pieces and building supplies to Habitat for Humanity. Recycle metals and cardboard locally.
Purchase products and materials made from recycled materials--such as finger jointed lumber, engineered and synthetic wood products, cellulose insulation products, etc.
Control litter. A clean site contributes positively to the neighborhood, roadways and waterways by keeping trash and litter in check.
Green Building On-Line The green building concept has been catching on so well that websites devoted to the topic are cropping up everywhere. Here are some of the better ones to come down the virtual pike since we last listed green web resources back in January. http://www.greenbuilder.com/
The truth is there are ways to easily and affordably integrate sustainable or green techniques into convention building practices. However, there is no one nationwide answer to green building strategies. Every region should employ different green building techniques depending on the climate, material availability and building practices.
In one region--the hot, humid Southern states, comfort and energy efficiency--two basic tenants of any green built home, are most impacted by the infiltration of outside air and moisture, summertime solar gain and from internal loads, such as electric lighting. Trying to fix only one of those things to create a more comfortable and efficient home won’t work. A house is a system and one component, such as a power attic fan, can effect another seemingly unrelated feature, such as mold growth under a bathroom vanity.
There are some ways within convention building technology to solve the infiltration problems that raise heating and cooling costs in a home. They are:
1) Install a moisture and vapor retarder on the outside surface of exterior walls. Remember, you want to keep humidity from infiltrating the living space from the outside (unless you have high sources of internal moisture generation).
2) House wrap that is well taped, and/or 30# felt paper installed shingle style so water sheds.
3) Make sure all flashing is installed shingle style. This means the upper piece overlaps the lower piece. This is a very common mistake found on nearly all jobsites.
4) Do not use vapor barriers on the inside surface of exterior walls--including vinyl wall coverings.
5) Go easy on the amount of recessed cans for lighting (even the so-called airtight ones). They puncture the thermal envelope of the structure and allow outside air in.
6) Try to restrict unnecessary light switches and electrical boxes on exterior walls. They too puncture the thermal envelope.
7) Never use anything but well-sealed ducts to move conditioned air. Unlined return air wall chases are bad in terms of lost efficiency, as are open return air plenums above dropped ceilings.
8) Wet, blown, borate-based wall cavity insulation is especially effective in reducing infiltration--and cellulose from recycled cardboard and paper is very green! This material makes good use of post-consumer recycled products, and the borates are a natural insect repellent.
9) A vented crawl space can create more moisture and humidity problems than it solves.
10) Power attic ventilators can cause moisture and humidity problems, as well as lead to higher energy bills. Passive attic ventilation, especially when combined with a radiant barrier, is better.
|Fannie Mae and NAHB are demonstrating their continued support of green building through a new partnership that will test and develop a menu of mortgage financing products based on environmentally-efficient criteria. The two organizations will work with home builders, lenders and other community partners to address the growing need for more creative home financing methods, according to Fannie Mae chairman Franklin D. Raines.
Six pilot cities have been identified where local HBAs and Fannie Mae Partnership Offices can begin to work together to develop initiatives that emphasize the efficient use of resources, such as energy and water, in the design, construction and operation of homes. The pilot cities are Atlanta, Columbus, Albuquerque, Denver, Los Angeles and Seattle.
Fannie Mae is providing an additional $100 million for investment in initiatives that test new housing finance products, support local green builder efforts, and develop creative solutions to environmental issues with community partners in those cities. The company recently revised its Energy Efficient Mortgage pilot by providing an underwriting variance that recognizes the added value of energy efficiency and translates the monthly energy savings into additional mortgage funds.
Treating unwanted solar gain, like infiltration, doesn’t require throwing out what you know, using a host of new materials or building in a lot of expensive features. It does require that you think differently about the way you build. For example:
1) Orient the home on the lot so that exposure to the afternoon sun is minimized.
2) Darker roofs absorb head, as do concrete tiles. 3) Ample roof overhangs make for less building maintenance and happier, more comfortable clients.
4) Shade all the east, south and west facing windows from the spring, summer and fall sum. Low E windows are not a substitute for proper shading. A well-shaded double pane window will outperform an unshaded high performance Low E glazing.
5) A radiant barrier on the underside of the roof will substantially reduce attic temperatures, thereby reducing cooling bills and enhancing occupant comfort. Radiant barriers also make it okay to run air conditioning ducts in the attic. These ducts install are easier to install and seal.
6) Radiant barriers will not degrade roof shingles.
7) Radiant barriers need to be installed in conjunction with continuous soffit and ridge venting--and insulation baffles at every rafter cavity.
The situation isn’t much different when the subject is lighting. Building a green home means accepting that the way it has always been done isn’t the only way. Consider these lighting options in your next home.
1) Become familiar with new types of fluorescent lamps, especially the thinner T8 type. The light quality is superior and you can get a range of color correctness.
2) Fluorescents put out very little heat and last longer than incandescents and halogens.
3) Halogen lamps do put our more lumens per watt--but still produce a lot of heat that the air conditioner will have to fight.
4) Go easy on the use of recessed cans. Fluorescent ones are better but the cans still make for punctures in the home’s thermal envelope.
5) Proper daylighting, especially indirect from high windows, can make for substantial energy savings--and increase worker productivity. (Clerestory windows do this well; and if operable, can be used to naturally siphon heat out of the space below in the spring and fall.)
Use your creativity to come up with the solutions to improve the efficiency and sustainability of all the aspects of building a home. There are locally appropriate strategies, materials and methods for building green homes that are affordable and mainstream.
Peter Pfeiffer is a principal in the Austin, Texas-based architectural and energy consulting firm of Barley + Pfeiffer Architects, specialist in residential and commercial sustainable building design and energy consulting. Pfeiffer has spent the past 20 years developing methods to mainstream green building. He first presented these ideas at the National Green Building Conference in Denver.
Managing Waste on the Jobsite