Posts Tagged ‘sustainability

29
May
08

Greener Than Green: Hempcrete

Hennep (hemp)

Texas may not usually be the state that immediately springs to mind when the words “bold innovation” appear in the same sentence, but The Woodlands, Texas, a community near Houston, is the site of America’s first hempcrete building. T. L. Hamilton tells us about it in the Montgomery Courier, while interviewing builder Gail Moran of Old World Exteriors. Moran told the reporter,

We’re cycling back to that traditional look and feel because it works better in some cases than the newer technology…I am so desperately wanting to make a difference in the way we currently build. I would like to see more people use natural products. I think they’re better for us and they look better.

How to build green is a topic on everyone’s mind these days, and hempcrete fulfills the requirements of being made from natural materials, being non-toxic, and providing energy efficiency. Formed into foot-thick walls on a wooden frame, the material eliminates the need for both insulation and sheet rock. Such walls are “breathable” and have a pleasant, natural appearance, as well as the ability to alleviate noise pollution from the outer world.

Skipping over to NaturalEnvironment.com, we learn that sustainable housing and hemp products go together like sunshine and picnics. It’s being used for fiberboard, mortar, stucco, insulation, fencing, pipe, and other housing-related applications, all over the world. Hemcrete, Isochanvre, Canobiote, and Canosmose are some of the trade names under which these products are marketed.

Hempcrete, which can be used in the same way as concrete, is made by mixing hemp, lime, sand, plaster and cement. It is mixed on site and sprayed onto the frame. Aside from doing away with the need for insulation, the material is waterproof, fireproof, and resistant to weather, rodents, and rot. It is said to be seven times stronger than concrete, as well as being more elastic, thus less prone to crack, and half the weight of concrete. Rather then emitting carbon dioxide, the construction of a hempcrete building can remove carbon dioxide from the air and trap it.

From another eco-friendly source, we learn that the growing of hemp yields four times as much material as the equivalent amount of land planted in trees, and can be harvested yearly rather than every 20 years. It grows well in many different climates, and its deep root system helps to prevent soil erosion. There is no need for herbicides, and very little call for pesticides in its growing; and since the ever-shedding leaves add to the soil, the land is left in better shape than before the crop was planted, and can be immediately used again the following year without needing to rest.

So, Gail Moran has achieved the distinction, with her small pottery studio/chapel, of being the first builder in the United States to use a material that humankind has depended on for centuries. Unfortunately for America’s farmers, builders, and environmentally-concerned citizens, hemp may not be grown in the United States and must be imported from more advanced countries.

SOURCE: ” Building green: Local company using hemp concrete ” 05/24/08
photo courtesy of psd, used under this Creative Commons license

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07
Apr
08

AGS Case Study: Restoring 215 Fremont Street, San Francisco, California

215 Fremont San Francisco

The venerable L-shaped industrial building had been around since 1927, and had suffered badly in the 1989 Loma Prieta earthquake, and then stood empty for a decade. Its rebirth is described in “Renovated Office Building at 215 Fremont Street, San Francisco California,” one of the case studies detailed in Architectural Graphic Standards, 11th Edition, from the American Institute of Architects, published by WILEY. The piece was written by four of the participants: James Kellogg, AIA, HOK; Lynn Filar, HOK; and Navinchandra R. Amin, SE and Vivian L. K. Wan, PE, both of Middlebrook + Louie.

The team that took on the revival of 215 Fremont faced real challenges. A large part of the project consisted of figuring out just what they were dealing with, hindered by the fact that many of the original drawings were either missing or indecipherable. When the nitty-gritty evaluation phase started, some unpleasant facts turned up. For example:

Since the original construction, the building had experienced differential settlements of up to 5 inches. Core samples and dynamic load tests of the existing floor slabs provided data necessary to evaluate the viability of components of the existing structure…

A large part of the evaluation process consisted of cranking up ETABS and SAP 2000, respected CAD programs that together gave a picture of how nicely the building would work and play with gravity and seismic loading. The prognosis wasn’t good. For starters, an earthquake would turn the ground beneath 215 Fremont into soup. How would they get this thing to stay up? Equally important was the need to satisfy ever-evolving building codes. We’ll let them tell it:

A new structural system needed to be developed for the project that would be sufficiently stiff to alleviate the induced internal forces in the existing floor slabs and punched exterior walls. Additionally, the structural system needed to use the full length and width of the structure to minimize the seismic overturning forces applied to the foundation…

As often happens, necessity gave birth to invention, and an elegant, innovative solution was arrived at.

This retrofit of an early twentieth century building led to the creation of a unique connection between steel braces and concrete columns, as a combination structural system comprised of steel-brace, frame-and-concrete shear walls was developed to meet all critical requirements.

The article explains exactly, and in great detail, how the team did it. And that’s not all. Every bit of 215 Fremont was remade into a paragon of sustainability and a fully compliant respecter of seismic requirements. What had once been basement storage space was now a much-needed parking facility. From bottom to top, from the new pedestrian-friendly retail arcade to the attractive rooftop terraces, the whole edifice was transformed. Impressed, the Structural Engineers Association of California gave the building its coveted Excellence in Structural Engineering Award.

215 Fremont, later also known as the Charles Schwab building and the Emporis building, was a showpiece as its neighborhood morphed into the happening “multimedia gulch.” When the project was finished in early 2001, a major corporation immediately occupied the entire building. The renovators had successfully made a statement: the cultural tone of the whole area had been elevated.

But any project of this kind also raises disturbing questions about the ultimate futility, in the event of catastrophic emergency, of even the strictest building codes.

SOURCE: “Renovated Office Building at 215 Fremont Street, San Francisco California” 2007
Photo courtesy of WILEY by Michael O’Callahan