Category Archives: Structure

This Week in Prototype News

The big blizzard of ’09 temporarily put the kibosh on construction, but we’re back up and running.  The Hemcrete forms have come off of the first floor, Serious Materials windows have arrived, and the roof is moving forward, with horse drawn, local, sustainably harvested hemlock fascia boards from Mountain Works installed this week.

If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Wall with Custom Hemcrete Forms
Wall with Custom Hemcrete Forms
Wall after Hemcrete Forms are Removed
Wall after Hemcrete Forms are Removed
Serious Materials Windows Have Arrived
Serious Materials Windows Have Arrived
Serious Materials Windows Waiting for Installation
Serious Materials Windows Waiting for Installation
Head and Jamb of Hemcrete Window Opening
Head and Jamb of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening

Sustainably Harvested Hemlock Fascia
Sustainably Harvested Hemlock Fascia

Closeup of Future Patio Connection at West Wall
Closeup of Future Patio Connection at West Wall
Nauhaus Prototype as of December 31, 2009
Nauhaus Prototype as of December 31, 2009

Electrical Completed, Lime Technology Pays a Visit

Click here to view the entire Nauhaus Prototype Construction Chronology.

We were excited to have Ian Pritchett and Mario Machnicki from Lime Technology, makers of Hemcrete, come by to check out our building for the first time.  We had some great discussions about Hemcrete, earthen blocks, construction details and more.  The electrical work has been completed, and the walls are ready for the hemp installation.

Jeff Buscher, Tim Callahan, Ian Pritchett, Mario Machnicki
Jeff Buscher, Tim Callahan, Ian Pritchett, Mario Machnicki
Ian Pritchett and Jeff Buscher talk about earthen blocks.
Ian Pritchett and Jeff Buscher talk about earthen blocks.
Southeast View
Southeast view of the nearly-completed framing of the Nauhaus Prototype
Electrical Box Installation
Electrical Box Installation
The electrical boxes are mounted on blocking so that they will be flush to the inside of the 12" walls.
The electrical boxes are mounted on blocking so that they will be flush to the inside of the 12" walls.

Asheville GO Helps Out

Today, the folks from Asheville Green Opportunities came to help out.  In the meantime, Matt and his crew started putting up rafters.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Asheville GO
Asheville GO
asheville go 2
Asheville GO Volunteers
Installing Blocking for Electrical
Installing Blocking for Electrical
Tony Beurskens Directs Asheville GO Volunteers
Tony Beurskens Directs Asheville GO Volunteers
Elijah and Chris
Elijah and Chris

Finished Scaffolding
Finished Scaffolding
Matt Installing Rafter
Matt Installing Rafter
East Gable
East Gable

Slab Edge Insulation and Drain

Today the foam insulation and drain were installed at the edges of the stem walls, and the CMU was sealed.

Click here to view the entire Nauhaus Prototype Construction Chronology.

This insulation will serve as a thermal break for the concrete slab.
This insulation will serve as a thermal break for the concrete slab.

The CMU is sealed to lock out moisture.
The CMU is sealed to lock out moisture.
These ties in the side of the CMU will serve a a mechanical connection to the spray foam insulation.
These ties in the side of the CMU will serve a a mechanical connection to the spray foam insulation.


Vapor Barrier Under Footers

Today a 20 mil. vapor barrier was laid in the trenches.  The concrete footers will be poured on top.   Radon pipes were installed for future venting if necessary, and greywater pipes were stubbed-out in hopes that one day a legal greywater system will be possible.

Click here to view the entire Nauhaus Prototype Construction Chronology.

View of Completed Vapor Barrier from Southwest
View of Completed Vapor Barrier from Southwest

tim vapor barrier
Tim Callahan
Stubbed-out Radon and Greywater Pipes
Stubbed-out Radon and Greywater Pipes

Missed Opportunities in Structural Sustainability

April, 2009
Structural Sustainability – discussions of sustainability and preservation as they pertain to structural engineering
Missed Opportunities in Structural Sustainability
Ben Hays, P.E., S.E., LEED A.P. and David Cocke, S.E.

Many structural engineers view the sustainable building movement as affording them little opportunity. Additionally, the predominant metric for measuring sustainable buildings, the LEED (Leadership in Energy and Environmental Design) rating system, offers few points for specifically structural solutions. To date, engineers following the LEED scorecard can recommend fly ash in concrete, recycled materials in steel, and sustainably harvested FSC wood. Beyond that, however, most engineers agree in principle with the comments of a LEED consultant in a recent meeting the authors attended: “As structural engineers, you guys can’t do much for sustainability.” This article argues otherwise, looking at the growing link between the reuse of buildings and sustainability and the role structural engineers can play in this type of design.

In 1987, the Bruntland Commission issued a report to the United Nations that included what has become the most widely accepted definition of sustainability as: “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”[1]. Since that time, most discussion about sustainability has included three aspects: environmental, economic, and social sustainability [2]. The common approach to sustainability from structural engineers (where there has been any approach at all) has focused almost exclusively on the environmental elements, in particular specifying reusable or renewable materials. There is a great need for broader thinking about sustainability from the structural engineering community. As engineers, we can significantly expand our impact on environmental sustainability, as well as contribute to economic and social sustainability, with only minor shifts in our thinking and practice. To do this, we must first understand the concept of embodied energy as well as become more willing to work with existing buildings.
Embodied Energy and Existing Buildings

When a building is constructed, significant amounts of energy are consumed in extracting, processing, and assembling raw materials into the finished product. Studies suggest that a building’s embodied energy ranges anywhere from 15 to 20 percent of its total life cycle energy use [2]. This reality lends credence to Carl Elefante’s adage: “the greenest building is one that is already built”[3]. If a structure is demolished at or before the end of a building’s 50-year service life, all of its embodied energy is wasted. This energy waste is in addition to the physical waste created, as well as the energy required in transporting the physical waste to a landfill. Another increasingly selected option exists for the design team, namely adaptively reusing the building.

Recent projects serves as an example of how reusing buildings makes sustainable sense. The authors completed an adaptive reuse of a 1950s, 2-story concrete warehouse (Figure 1). The building is not on the national or local historic registers and the owner could easily have chosen to demolish it and erected a new, similar sized building in its place. Instead, it was decided to retrofit and reuse the building, though not necessarily for sustainable reasons. Using an online calculator, the embodied energy in the 50,000 SF building is 56,500,000 million BTUs [4]. In addition, the energy required to demolish the building would be 775,000 MBTUs, a small percentage of the embodied energy. Finally, by not demolishing the building, an equivalent amount of energy saved by not having to construct a new building, another 56,500,000 MBTU. While any number of comparisons could be made for this quantity of energy, the total energy represented in the sum embodied energy+demolition+new construction is roughly equivalent to 1,000,000 gallons of gasoline. Ironically, a new energy efficient building would take longer than 50 years for its own efficiencies to equal, and thereby pay back, this same amount of energy.
Figure 1: Reuse versus demo: embodied energy calculations.

The numbers related to a building’s embodied energy present a compelling case for expanding our impact on environmental sustainability beyond specifying materials. The concept of embodied energy does not require a cognitive leap of faith. The challenge for engineers is what Patrice Frey quotes as: “shifting the presumption on stewardship of built heritage to favor reuse” rather than demolition [2]. Many engineers, whether through training or experience, do not like working with existing buildings. This is even more the case in California, where “seismic concerns” regularly trump desires to keep otherwise well-performing buildings. If we want to have an impact on sustainability, we must change this prevailing belief within our profession and be more vocal about our efforts in our industry.
Opportunities for Structural Sustainability

The opportunity presented to engineers at the intersection of reusing buildings and sustainability is significant. The Brookings Institute estimates that, by 2030, the United States will replace 82 billion square feet of its current building stock [6]. Our willingness to work with, rather than preemptively condemn many of these buildings, will go a long way toward contributing to sustainability. Architects, developers, and building owners look to engineers to provide honest recommendations regarding the potential of existing structures. Firms that become experts in working with, rather than avoiding, existing buildings will gain a competitive edge as market conditions and sustainable concerns increasingly favor building reuse.

One might look at the idea of reusing buildings and embodied energy and think that we are merely expanding our impact on environmental sustainability alone. While on the surface this is true, reusing existing buildings also promotes the economic and social aspects of sustainability. According to a report by the Brookings Institute, the decision to reinvest rather than tear down or abandon a building “presents convincing evidence that ‘preservation pays’ when viewed in economic terms.” This payment comes in the form of driving economic growth, job creation, friendliness to small businesses, and promoting high wage jobs. All of these are forms of sustainable economic development when viewed long term. Additionally, reusing existing buildings adds to social sustainability by protecting social diversity and maintaining our sense of place in our increasingly globalized world. Patrice Frey expands greatly on how existing buildings promote social and economic sustainability, and the reader would be well served to read her paper [2].
Conclusions

In closing, we return to the question of how LEED recognizes the contributions of the structural engineer to sustainability. At present, LEED primarily credits environmental sustainability in the form of material specification; recycled content in concrete and steel, and sustainably harvested wood. In its current form, LEED awards the same number of credits for reusing 75% of the building’s walls, floors, and roof as it does for specifying bike racks and showers for 5% of a building’s occupants. At present, it does not address the idea of embodied energy directly and does not take into account the cultural heritage associated with preserving buildings. LEED 2009, which launched in March of this year, gives much greater credit than its predecessor to metrics such as Community Connectivity and Alternative Transportation, both of which favor existing buildings. In addition, there is now an Alternative Compliance Path that specifically recognizes an existing building’s embodied energy. Lastly, a Sustainable Preservation Coalition has been formed to incorporate preservation, social, and cultural values into LEED, though probably not until its next release in 2011 [5].

Admittedly, the choice to reuse existing buildings does not rest solely in the hands of structural engineers though our opinion often becomes the deal-breaker. We must partner with owners, architects, and developers in order to maintain our built heritage. Engineers have a more extensive role to play than merely specifying sustainable materials. If understood and promoted properly, the intersection of sustainability and reusing buildings affords structural engineers a great opportunity for professional development, marketing, and occasion to contribute to a greener future.▪
Ben Hays, P.E., S.E., LEED A.P. is a Design Engineer with Structural Focus, a Structural Engineering firm in Los Angeles. He can be reached at bhays@structuralfocus.com.
David Cocke, S.E. is owner and principal of Structural Focus. David currently sits as the SEAOC-appointed Alternate member of the California Historical Building Safety Board. He can be reached at dcocke@structuralfocus.com.
References

[1] Brundtland, Gro Harlem and World Commission on Environment and Development. [1987]. Report of the World Commission on Environment and Development: “Our Common Future.”

[2] Frey, Patrice. [2007]. Making the Case: Historic Preservation as Sustainable Development. (www.preservationnation.org/issues/sustainability/additional-resources/DiscussionDraft_10_15.pdf, accessed 1/16/09)

[3] Elefante, Carl. [2007]. The Greenest Building Is…One That Is Already Built. Forum Journal. Vol 21, No 4.

[4] www.TheGreenestBuilding.org

[5] Campagna, Barbara. [2009]. How Changes to LEED™ Will Benefit Existing and Historic Buildings. (www.aia.org/hrc_a_200812_campagna, accessed 1/16/09)

[6] Nelson, A.C. (2004) Toward a New Metropolis: The Opportunity to Rebuild America. Brookings Institute. (http://www.brookings.edu/reports/2004/12metropolitanpolicy_nelson.aspx)