Construction, as many of you know by now, is one of the biggest single sources for waste and may be responsible for as much as 30% of the volume used in some landfills. And, because commercial space is turned over more frequently, the interior build-out of office space is one of the biggest sources of construction debris and waste. As companies change their staff, the space they occupy fluctuates, and often old spaces are torn out and new spaces built with different configurations.

Since the spaces in an office are not part of the structure (in most cases), the walls that divide offices and meeting rooms can be relatively quickly disassembled and rebuilt in a new configuration without affecting the building structure. This flexibility appeals to building owners and tenants alike, because space can be easily customized to meet the particular needs of any tenant. But it leads to an awful lot of waste, as well.

A new system of wall construction devised by Sean Dorsy, a graduate architecture student at The Catholic University of America, uses standard 4 x 8 sheets of plywood cut with slots so that the panel can be unfolded like an accordion to make a wall structure to replace standard stud construction.

This wall system provides savings of weight (138 lbs versus 245 lbs), wood (since plywood uses trees more efficiently than 2×4s), and money ($51.89 for the plywod system versus $55.89 for an equivalent section of stud wall). But also, unlike the standard wood stud construction, the system is much easier to disassemble, and therefore easier to re-use when the time comes to reconfigure the space.

A number of office furniture companies produce panelized wall systems that are used to allow businesses and building owners to quickly install and reconfigure spaces. These wall panels are also demountable and reusable, so that a space can be reconfigured rather than demolishing and rebuilding walls to reconfigure space as companies’ needs change or building tenants come and go. In addition to saving materials and reducing waste, these panelized systems are typically quicker to assemble.

Panelized systems have their drawbacks, as well. The look is usually not as nice as a gyp board wall, with more exposed seams and a less refined appearance. They are also frequently covered with vinyl wallcoverings, which have their own environmental costs many people would rather avoid.

Dorsy’s wall system makes somewhat less sense for residential uses, because in most typical home construction some of the interior walls are structural, and the walls are not moved as frequently. Building some walls with standard stud construction and others with the expanded plywood method might turn out to be more costly than having all walls built in the same fashion and from the same materials.

The problem with any system of demountable walls (whether using Dorsy’s system or a commercial panealized wall system or some other scheme) is that interior spaces rarely work out perfectly evenly within a space. If you have 4-foot-wide panels and you need 14 feet of wall, you still end up cutting pieces and producing waste. And then, when the time comes to reconfigure the space again, those already cut pieces are usually seen as waste and are consigned to the landfill at that point. Still, this typically produces less waste than a full build-out and tear-down would create.

via: Architect Magazine

The most common materials are plastic laminate and solid surface materials. Plastic laminate is a thin sheet of colored plastic glued to a backing which is most often composition wood board - a combination of wood bits and glue - which offgasses formaldehyde from the urea formaldehyde glue used to make it. Solid surface countertops (including such brands as Corian) are made from plastics and epoxy resins. Some solid surface materials have some mineral content (like Zodiaq, a sister line to Corian that incorporates quartz chips into the material), which lessens the use of petrochemicals and other synthetics.

There are many other possibilities to be considered. Individual style as well as tolerance for character and variability are also part of the decision-making process. A person who wants a very pristine appearance may not be suited for a material like soapstone, which will show marks and develop a character over time. Ideally, a countertop should be as long-lasting as possible, so that the material doesn’t need to be replaced and it stays out of the landfill.

Granite is a natural stone material. It does not wear out or decay, and can potentially be re-used. It does not break down, and discarded countertops only contribute bulk to landfills. The negatives with using granite include the mining process and the shipping. Mining is inevitable for any mineral product, and quarrying of granite for building purposes has a lot lower overall environmental impact than, say coal mining. As a stone product, it is pretty resistant to heat, but some things can leave stains on it. Increasingly, stone products are being imported from Asia, and the shipping impacts and environmental costs of that versus more locally sourced materials should be considered. Soapstone, slate, and other alternative stone products may be another option, particularly if they are regionally produced near the area where they are to be installed.

A number of solid surfacing products have more of a green edge to them these days. Avonite has a line of solid surfacing countertops which have some recycled content. They are re-using reclaimed solid surface material (presumably pre-consumer recycling, but reducing waste nonetheless) in one line. IceStone is a product that uses recycled glass and concrete. It is not a solid surface material. The company also notes that "McDonough Braungart Design Chemistry (MBDC) awarded Cradle to Cradle™ SILVER Certification to IceStone durable surfaces." Paperstone is a product made from recycled paper, and includes a line that uses 100% post-consumer paper in its products. Paperstone is FSC certified, and the company notes that it uses a water based resin to manufacture its countertops. All of these options offer increased durability (even PaperStone resists heat up to 350 degrees F). But the manufacture and shipping may be a consideration. (PaperStone is manufactured in Washington state, and IceStone is made in Brooklyn, so if you are within 500 miles of either of these manufacturers, LEED would consider them a local material supplier.)

There is even the option of a concrete countertop for a serious do-it-yourselfer. Concrete countertops offer great flexibility in configuration, and can be inlaid with decorative elements and finished in a wide range of options. Concrete is generally produced fairly locally, so the shipping is reduced. But there is more embodied energy in manufacturing concrete than in some other materials. And the production of cement is a major contributor to atmospheric pollution.

Stainless steel countertops are used in commercial kitchens because of their durability and easy cleanability. While stainless steel countertops might be an option for some, they are generally too institutional looking for most households. Steel has much more embodied energy in the processing of metal. But it is also eminently recyclable at the end of its useful life. Unless there is another use for a natural stone or a synthetic countertop, it will most likely be down-cycled into some lesser use, or else go into a landfill. But a stainless steel counter can be recycled into other steel products.

Wood is another possibility that can be considered. Wood butcher block can be very durable, though it will develop wear and exhibit marks as it is used over time. While many people may not like the way it looks after a few years, the honesty of the appearance may be appealing to some, and the low impact nature of the material may make it a choice to consider.

This is no more a black and white issue than most other green building questions. This can depend on the particular situation and the specific needs of a particular project. I'm not going to give you a definitive answer, because I don't think that there is one, any more than I do for most green building topics (other than greener is better).

First, there is the issue of material content. On the one hand, the manufactured products often use some combination of wood fiber (which is often sawdust and other scrap that would otherwise go to waste) and plastic (sometimes incorporating post consumer recycled material). On the other hand, wood is a natural material. It is sustainable, in that wood can be grown and harvested. There are some deck materials that have natural rot-resistant properties, but these tend to be more expensive. There is also the question of whether or not they are sustainably harvested, as well as the issue of shipping these materials.

Maintenance is another consideration. Wood decks need to be stained and cared for on a regular basis. Even with regular maintenance, a wood deck will wear out over time, and pieces will need to be replaced eventually. Maintenance for the manufactured products is supposed to be lower. However, I have heard of more than one architect I know who put in Trex decks for their own homes and now have some problems with its performance. Other manufacturers are competing in this field now, as well, and there may be better products available.

End of life is another question to be addressed. Making a material like Trex is a downcycling use, and there isn't much that can be done with an old manufactured deck other than to landfill it. Wood decking, if it is untreated, can be allowed to decay naturally. But, if the decking has been treated, it is not going to break down readily. Decking treated with preservatives (whether it was the older CCA — chromated copper arsenate — which is now outlawed because it was leaching arsenic, or the newer ACQ — alkaline copper quaternary compounds — or one of the other current alternatives) is meant to not break down. In the long term, it will eventually decay, but it will be a much slower process. According to a Wikipedia article, "A report published in Wood and Fibre Science (Vol 36 pp 119-128, 2004) concluded that soil contamination due to the presence of CCA-treated wood after 45 years is minimal." In the interim, however, you probably don't want it in your compost.

Finally, the workability and durability of the material factor into the question. Contractors and installers like the manufactured products because they are easier to use. The boards are straight and regular. Warping, twisting, and cupping defects are not an issue. However, many of the manufactured deck boards have a noticably fake appearance, or do not look like real wood at all. I think a case can be made for either product, as long as one takes a careful look at the material sourcing, with FSC certification for real wood or high recycled content for a manufactured product.

Evacuated tube heaters are another method of collecting solar energy. Rather than running the water through a long circuitous course, each tube is a separate heat collector. It is made of a clear glass cylinder which allows sunlight to pass through, and a central heat collector tube. The evacuated tube insulates the collector element, which makes it more efficient in colder environments. The collector itself is typically filled with an antifreeze mix rather than just water. The top of the tube has a heat exchange element which is prevents contamination of the water being heated. The tubes are collected together in an array, with a manifold across the tops, containing the heat exchangers.

Image credit: Enviro-friendly.comEvacuated tube collectors are more efficent than water circulating collectors, and can reach higher temperatures, especially in wintertime. Because of their greater efficiency, a water heating system using evacuated tube solar collectors will generally be smaller than a comparable water circulating assembly. The cylindrical form of the tubes also means that the collectors are always perpindicular to the sun, while flat collectors lose more efficiency early in the morning and late in the afternoon unless they are rotated to track the sun (see diagram). Evacuated tube systems can also be easier to operate in a cold environment where concerns about the system freezing at night, particularly during cold winter months, is an issue.

Evacuated tube collectors also help to minimize maintenance. The collectors themselves are sealed, and the water system only has brief contact with the heat exchangers in the manifold. In the event of damage, individual tubes can be fairly readily swapped out, whereas holes in tubing and broken glass over a flat array can be harder and more expensive to repair.

There are a few tradeoffs with evacuated tube collectors. They tend to be more expensive. They can be broken (by hail or falling branches from nearby trees), which looses the vacuum and the efficiency of the tube, and necessitates eventual replacement. They are also sometimes unsuitable for snowy climates, as well, because the heat gathering element is insulated with a vacuum which means that the tubes themselves will stay cool, and can remain covered with snow instead of melting it off as the collector gets heated up.

In the right location, evacuated tube solar collectors can be a good choice for use in conjunction with a hot water system or a radiant floor system (or both). Any form of solar hot water system has a much shorter payback period than a photovoltaic system, and is well worth considering. Evacuated tube collectors are not as well known, but should be part of that evaluation, as well.

Links:

Silicon Solar

Sunpower Canada

Enviro Friendly Products

Wikipedia

Tankless water heaters have no hot water storage (hence tankless), but can quickly raise water temperature by as much as 50 degrees F (~30 degrees C). They can do this with a flow rate ranging from 4 gallons per minute (GPM) to as much as 9 GPM. Tankless heaters are also much smaller than conventional water tank heaters, which can be a consideration for smaller homes where space is at a premium.

Depending on usage patterns, a tankless water heater can provide hot water much more efficiently than a regular tank heater. One manufacturer's information lists an annual operating cost (based on 2004 prices) of $166 for their tankless heater versus $210 for a conventional natural gas water heater, and propane and electric conventional heaters are even more expensive to operate.

Tankless water heaters can allow "endless showers." Since the water is being heated as it is needeed, there is no concern about running out of hot water, while a conventional tank heater has a capacity, after which the hot water runs out and water that has entered the heater tank needs to be heated

Tankless heaters may not be for everyone, however.

Supply water temperature can be a factor. Regions with cold winter ground temperatures may have incoming water that is 40-50 degrees F, which may not be able to be adequately heated for hot water needs. More temperate locations will likely be better for tankless water heater installations.

Tankless water heaters also have a much larger fuel supply requirement. In order to provide such a drastic temperature change, simple physics dictates that they need to use a lot of energy very quickly. Over the course of its life, the tankless heater doesn't use as much fuel as a conventional water heater, but when it uses fuel, it uses a lot of it very quickly. This can make retrofitting a tankless heater into an existing home difficult, because the gas line to the existing water heater may not be large enough to supply the needed gas for a tankless heater.

Are they right for you? As I'm increasingly fond of saying, it depends. A home for a larger family where multiple water uses (more than one shower at a time, washing clothes or dishes while showering, etc.) may put more demand on the system than it is able to supply hot water for. But a home for a single individual or a couple who are careful about not crossing their water use, they may be a way to have significant energy savings.

The principle is to maintain a separation between the different aspects of the building in order to be able to make repairs and do upgrades with a minimum of interference with other elements of the building. Open building stipulates separate zones or chases for different functions and services. This will, for example, make it easier to change plumbing systems without needing to repair other systems that cross or interfere with access to the necessary parts of the plumbing system.

Open building also makes construction easier by minimizing the interference between different systems, so that the installation of different systems can take place at the same time, rather than needing to be staggered one after another. With each trade and system given its own designated area, the builders (and also the future remodelers or repairers) of those systems can do their work with much less concern about damaging other elements of the building.

Open building lays out six "layers" with different lifespans. They are:

• Site - the location; building site itself. Timeless duration
• Structure - the framework; the "bones" of the building. 100 to 300 year lifespan
• Skin - the cladding. 40 to 100 year lifespan
• Space plan - the interior partition walls. 10 to 30 year life
• Services - electrical, plumbing, mechanical, and heating/ventillation systems. Updated every 1 to 10 years
• Stuff - belongings and furnishings. Can change monthly

Open building is often incorporated into pre-fab systems. Concentrating all of the plumbing elements in one area, for example, helps to put all elements of that system in one area for easier repair access. It also serves to reduce the amount of plumbing material needed. If all water uses are concentrated in one area, there is less piping needed which can mean a reduction in the amount of copper or other material used in the construction. The benefits of engineered construction with pre-fabrication, rather than having all of the installation of the services done on-site, can make for better use of materials and better buildings.

Taken to its extreme, however, open building can become restrictive, forcing configurations on the building that do not serve the needs of the inhabitants. If other parts of the plan are forced into awkward configurations in order to accommodate the structure of open building, then the savings in that one area may be lost in other areas. However, there can be benefits to understanding open building even without wholly embracing the open building system as the chief principle for constructing a building. Looking at the building with an eye to the life cycle of the different systems can lead to a better building, and can help reduce later problems.

Buildings need to be built to meet immediate needs. But they also need to be constructed in a way that future needs and changes to the building are also given consideration. Much in the same way that we need to conserve resources for the use of future generations, the buildings we build today will also be used and re-used well into the future, and a longer-term approach to building is another part of building green.

Article: Reinventing the House (Fine Homebuilding reprint - PDF)