Grantee Research Project Results
Final Report: Green Oak as a Sustainable Building Material
EPA Grant Number: SU835495Title: Green Oak as a Sustainable Building Material
Investigators: Shelton, Ted , French, Robert C. , Taylor, Adam M , Bennett, Richard M , Hatcher, Alex , Reed, Bhen , Retherford, Jennifer , Iden, Matt , Cunningham, Michael , Wright, Miranda , Graham, Natalie , Poor, Noah , Attea, Paul , Heldic, Rijad , Sugiyama, Sherif , Whitmore, Steven , Stuth, Tricia , Rasnake, Tyler , Kessel, Wilson
Institution: University of Tennessee
EPA Project Officer: Packard, Benjamin H
Phase: I
Project Period: August 15, 2013 through August 14, 2014
Project Amount: $14,977
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2013) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Awards , Sustainable and Healthy Communities
Objective:
The research has two primary objectives:
- To develop contemporary green (un-dried) oak construction techniques for the US building market that will allow currently underutilized heart centers of logs to be used as an extremely low energy, carbon friendly, beautiful, and high value wood product – as structural members in sustainable buildings.
- To develop technical documentation necessary for the construction of a demonstration project that will further acceptance of this abundant, renewable regional resource.
Wood is a renewable resource requiring far lower energy inputs for its harvesting and processing than do competing materials. The Appalachian hardwood region is one of the most productive forests in the world, annually adding about twice the volume of timber to its reserve as is harvested, despite supporting a robust industry of diverse, high-value hardwood products such as flooring, trim, and cabinetry. The “heart centers” of hardwood logs, however, are an exception to the efficient use of this resource. Because this wood has defects that limit its usefulness for traditional dry lumber products, this portion of the log is routinely sold green (un-dried) as “cants” used to manufacture shipping pallets – an extremely low-grade use for such an otherwise highly desirable resource.
Our Phase I research used a series of design studios and interdisciplinary seminars to conduct fundamental research necessary to allow for the use of green oak pallet cants as a structural element in the US building market. Despite a centuries-long history, there is very little contemporary architectural or engineering knowledge in the US about using green oak in building design and no pathway in building codes for using green oak structural members with cross sectional areas as small as pallet cants. Our work addressed both of these problems. Responding to the specifics of species, dimensions, and properties of oak pallet cants, our work endeavors to transform this resource to structural use while requiring no operational changes for local saw mills.
The use of oak pallet cants as structural members has profound implications for people, prosperity, and the planet. As an undried timber product, it has extremely low energy inputs (less than 1/10th that of steel alternatives). White oak is naturally rot- and insect-resistant, offering the potential for durability in exterior applications without the need for chemical preservatives, is renewable, and is regularly sustainably harvested throughout the region. The opportunity to convert a local, low-value product to a high-value product with significant potential for penetration into the construction market would undoubtedly strengthen the regional hardwood timber economy, which consists primarily of small land owners and small mills. Finally, end users would enjoy buildings that utilize a beautiful, regionally specific material as an integral part of their structure and architectural expression.
Summary/Accomplishments (Outputs/Outcomes):
Findings during Phase I included:
- Literature review on contemporary green oak building techniques (primarily European examples.)
- Speculative adaptation of contemporary green oak building techniques to the dimensional limitations (4”x6”x16’) of pallet cants.
- Evaluation of speculative proposals through three-dimensional digital modeling.
- Evaluation of six types of joining techniques against 15 criteria.
- Testing of highest evaluated joining techniques by kiln drying full-size mockups to simulate complete air drying.
- Both schematic and detailed development of a potential “customized” demonstration project at the West Tennessee 4-H camp. Exploration included architectural drawings, details, renderings, and models. These explorations utilized commonly used rules of thumb for the sizing of the components of the structural frame.
- Identification of a second potential community partner, Red Bird, for the Phase II demonstration project.
- Development of a simplified but adaptable bent construction system for use in the low-income housing market. The bents in this system fit within the 8’-6” standard trucking width to allow for prefabrication and remain well within the material’s spanning capacity to avoid the need for composite members.
- Exploration of the variability of the “systematized” approach through eight schematic design proposals. These proposals were documented through architectural drawings, renderings, and models.
- Detailed development of a potential “systematized” demonstration project at Red Bird. Exploration included architectural drawings, details, renderings, and models. These explorations were guided by the work of a structural engineering student who designed the specifics of the joining methods.
- Development of a secondary focus on the use of green oak pallet cants for siding applications.
- Analysis of previously developed break testing data that found the structural properties of pallet cants to be similar to those of construction grade white oak.
- Creation of a “teaching sculpture” on the UT Agriculture Campus that uses spare pallet cants from the research; standing them on end in a straight line so that dimensional variation in the individual members can be observed over time.
Conclusions:
Green oak pallet cants hold significant promise for use as a structural building material, particularly in housing and small commercial applications. This is true both in a customized mode of construction that requires specific design of composite members for spanning, and in a systematized mode of construction that relies on a prefabricated bent system that adheres to an 8’ spanning module but is highly variable in terms of its space making possibilities. Adoption of these methods by even a small portion of the housing and small commercial construction markets would have sizeable positive impacts in terms of people (affordable construction from a beautiful, regionally-specific material, potential demand for specialized green timber construction skills), prosperity (increased value of a currently low-value product for numerous small mills throughout the Appalachian hardwood growing region), and the planet (significantly reduced embodied energy in structural building frames and siding systems with associated reduction in emissions, reduced use of chemical preservatives as a result of using a naturally rot- and insect-resistant material.)
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
built environment, forest products, energy efficiency, embodied energy, housing, green design, environmentally benign substitute, conservation, design for the environment, green building, alternative construction material, architectural designRelevant Websites:
The Green Oak Initiative Exit
Twitter @UTGreenOak Exit with entries cross-posted at http://archinect.com/ Exit and selectively covered at http://archdesign.utk.edu/ Exit
P3 Phase II:
Green Oak as a Sustainable Building Material | 2015 Progress Report | 2016 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.