The economy definitely had an impact on this year’s West Coast Green with less venders but with less money that mean that people just had to get more creative with less moola such as the floating island, show gardens and even the sustainability built Jewish Sukkoth. The usual green rock stars like Eric Corey Freed and Michelle Kaufman made their presences felt with their energetic personalities.

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“Our homes embrace the principles of eco-friendliness and cost-effectiveness, without sacrificing beauty. We can ensure that each dwelling achieves a gold or platinum LEED rating, depending on the particular finishes, building systems, and site design an owner chooses.” ~ Michelle Kaufmann Designs

Each Glidehouse home is solar ready with other renewable energy system options possible such as geothermal, wind generator or hybrid systems. Designed for clean, simple living. The Glidehouse is built in a factory, using the most modern and environmentally friendly building methods and materials.

Some eco features of the Glidehouse include:

• using healthy finishes such as non-toxic paints and formaldehyde-free cabinetry.
• it meets the Energy Star® program standards for energy efficient homes and meets the performance standards of the American Lung Association Health House program.
• it’s insulated with an air-barrier, open cell foam insulation, and all wood-to-wood framing joints are caulked, which makes the home airtight, energy efficient, and less likely to produce mold.
• it uses water-saving plumbing fixtures, on-demand water heaters, and a mechanical ventilation system that is 30% more efficient than typical forced-air systems.
• energy efficient, dual-pane glass windows and doors are placed throughout the home to maximize cross-ventilation and natural lighting, minimizing the need for artificial lighting and climate control.

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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)

Prefab is a popular concept in green design circles and shows up regularly on a number of blogs. A few of the more prominent examples include: Inhabitat (Pre-Fab Friday); Jetson Green; Treehugger; BldgBlog; MoCo Loco; and even a website devoted to prefabs: FabPrefab. But it's a valid question that is being asked. How "green" is prefab building, and should it be embraced by those who want a greener building? Bob sums his article up this way: "I want to honestly question what is and what isn't 'green' about prefabrication and encourage others to do the same."

Prefab construction can be very green. The LivingHomes prefab illustrating this article is a LEED Platinum building. But, there are very few examples of prefabs that have LEED certificaion. And not every prefab qualifies even as a LEED certified building, let alone a Platinum one.

I'll highlight the points from Bob's article that I want to address, but I recommend reading the whole article.

Material waste/efficient use of materials - Because of the more modular and more engineered nature of prefabs, they often (but not necessarily) use modular dimensions that correspond to standard material sizes (such as using a 2' module to minimize waste from standard 4' wide sheet products like plywood and OSB). Some site-built projects use these approaches as well, but this depends on the designer and the builder, not the construction method.

Over engineering - I think this tag can be hung on site built projects as easily as it can on prefab. There are different ways that materials are used in each kind of construction. Bob's article points out some of the areas where prefabs need to have additional structure for transportation and erection purposes. Once the building is in place, this additional structure serves little useful purpose. On the other hand, for the site-built home, far too often, large, dimensional lumber pieces are used for headers for openings in non-loadbearing conditions where they are completely unnecessary, simply because it is common and traditional practice to do so.

Carbon footprint for transportation (and other uses) - Material delivery from distributed manufacturers to the prefab plant or to the supplier or retailer who then delivers it to the jobsite probably is slightly more efficient on the prefab side. If the prefab manufacture is fairly local to the final instalation site, it's probably beneficial to do the prefab. The greater the distance between prefabricator and final assembly site, the less benefit there is.

The benefits to having workers coming to a consistent work location (the fabrication plant) rather than driving all over the region (as many site-built tradespeople do) is probably a carbon benefit, as Lloyd points out in his comment. The factory, if it is in a cold weater climate, most likely has a heated space that requires additional power. But cold weather construction goes on for site-built homes as well, and 'salamanders' (large propane-fired space heaters) are used to heat these yet-to-be-insulated buildings under construction. I'm not sure ehich way this goes, but it's not as one-sided against prefabs as you might initially think.

A prefab also should benefit from being constructed in a shop environment where tolerances can be much finer. This allows for a building with tighter construction, which should pay benefits in reduced air infiltration, better insulation, more comfort and lower energy use. Exposure to the elements during construction can cause problems with the building later on. Fabricating the building in controlled conditions makes this much less of an issue.

Prefabs may also tend to benefit from a design that needs to take transport of the building into consideration. Though not an explicit requirement of prefabs, I think the general trend for prefabs is to be smaller than corresponding site-built structures. In many cases, the modernist aesthetic of prefabs also contributes to the building being smaller and more efficient. Fine finish is given precedence over raw square footage.

The whole issue of "green-washing" is key. Lots of businesses are seeing their customers asking for green products, whether they are selling soap or shirts or cars or homes. So, whether something is truly green or not becomes an important question consumers are asking. And, with so many competing definitions, and so many tenuous attempts to claim greenness, the question is a valid one.

As with many things that are green, I don't have a clear cut and definitive answer to offer. Instead, I'll say "It depends." (I use this phrase a lot, but it's probably appropriate here as elsewhere.) Pre-fab is a process, not an end-product. Therefore, it can be done well or badly. It's certainly possible to be very efficient and do site built construction. It's also possible to do wasteful and inefficient prefab manufacture.

In and of itself, pre-fab is not automatically "green." When done well, it can be a method that leads to a better constructed home, including one that uses fewer materials and operates more efficiently (meaning less carbon footprint over the building's lifetime, a much larger chunk of its carbon footprint to consider than its construction). In green building, we try to take a look at the larger picture, rather than only focusing on the final building alone. Life cycle issues, and the methods and processes all contribute to making a building green. It's the execution of the concept, and not the idea itself, that makes or breaks a prefab as a greener building.