Grantee Research Project Results

Final Report: Comparing the Sustainability of a Compressed Earth Block House to a Conventionally Framed House Built to National Green Building Standards

EPA Grant Number: SU835090
Title: Comparing the Sustainability of a Compressed Earth Block House to a Conventionally Framed House Built to National Green Building Standards
Investigators: Holliday, Lisa M. , Butko, Daniel J. , Crandall, Aaron , Rodman, Adam , Farber, Benja , McManus, Bill , Graham, Charles , Barrientos, Estefania , Sivuilu, Hervé , Berdis, Jesse , McNeil, Katy , DeFreitas, Kyle , Renevier, Kyle , Reyes, Matthew , Johnson, Mitch , Lyons, Molly , Boer, Paul , Everest, Peter , Moheb, Ryan , Williams, Scott , Poole, Travis
Institution: University of Oklahoma
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $14,897
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities

Objective:

The multi-disciplinary team of students was formed with the purpose of designing, field-testing, constructing, and then monitoring the performance of a house built of Compressed Earth Blocks (CEBs) for Cleveland County Habitat for Humanity (CCHFH). CCHFH is the local Habitat for Humanity affiliate serving all of Cleveland County Oklahoma. CEBs are made by mechanically compacting soil with high pressure into forms to create blocks, similar to traditional masonry units. The blocks are then used as the main structural system in the house instead of lumber, concrete, or brick masonry.

The objective of this multi-phase research project is to produce new knowledge and develop best practices for CEB construction processes. This will enable broad implementation of CEB technology in domestic and international housing construction. The CEB construction methods are comparatively simple for individuals and social organizations that rely on volunteer labor, i.e. Habitat for Humanity and other community efforts. Compressed Earth Blocks are inherently sustainable, economical, and energy efficient; they require little energy to produce, conserve natural resources, virtually eliminate landfill waste, and reduce energy consumption required for residential heating and cooling. With appropriate reinforcement, they have been proven structurally sound even in earthquake prone areas. If CEB construction can be demonstrated as a viable residential construction solution in Oklahoma (harsh winters, hot summers, and strong winds), then it is a viable option for almost any location in the developed or developing world.

To examine this hypothesis, the team has partnered with CCHFH to build a single-family residence using CEBs as load-bearing walls adjacent to a recently built CCHFH house constructed of traditional wood framing. The team chose to use this existing house as the control house not only because it is newly constructed, but also because it was built according to high standards for sustainability as required to meet National Green Building Standards (NGBS). The CEB house will be nearly identical to the control house in layout, area, and inhabitable volume. Both completed houses will be rigorously evaluated by the research team and an outside agency to compare sustainable features and to determine the NGBS score. In addition to these initial tests, both houses will be instrumented and monitored over time for structural performance, energy consumption, thermal properties, indoor air quality, and acoustical attributes. Based on these findings, CCHFH also plans to build a third residence that will be optimized for CEBs, using the knowledge of design and construction learned from this project.

As a first step, we partnered with CCHFH and received the EPA P3 Phase I Grant to conduct a multidisciplinary course during Fall 2011 that explored CEB manufacturing, conducted preliminary research, and designed the CEB house. The first phase was successful. The EPA grant was instrumental in identifying numerous related research projects, getting additional internal funds from the University, allowing professors and students to present four papers at Earth USA (a worldwide conference on earth building), and led to featured articles in a local newspaper. This publicity has led to inquiries from several potential post-doctoral students in addition to the frequent interest from current students, faculty, and the community.

Since the state of Oklahoma does not have a prescriptive earth building code, the building system must be engineered and tested for municipal approval. Phase I accomplished the overall testing and design requirements, including constructability, architectural layout, material attachment, expected energy use, predicted embodied energy, schedule, cost, soil mix design, the logistics and quality control of CEB production, and many other considerations. In Phase II the team will apply Phase I results to build, test, evaluate, and compare the CEB house to the control house. The funding will complete this project and publicly demonstrate CEBs’ potential for helping people prosper on our planet.

To cover the large area of research for this project, the faculty investigators enlisted students from various colleges and departments across the University of Oklahoma. All five departments within the College of Architecture (Architecture, Construction Science, Interior Design, Landscape Architecture, and Regional & City Planning) as well as the Department of Civil Engineering in the College of Engineering were represented.

This diversity amongst classmates ensured students approached problems from various viewpoints and continuously examined different methods of problem solving. The topics of research were just as varied as students’ interests listed below:

• Kyle Renevier tested how CEB walls resist in-plane shear.
• Travis Poole tested how CEB walls resist out-of-plane shear.
• Paul Boer calculated and checked the structural system for gravity loads.
• Katy McNeil calculated building code prescribed wind and seismic loads.
• Jesse Berdis and Kyle De Freitas studied the soil mix design for CEBs, coursing slurry (mortar), and interior plaster.
• Estefania Barrientos developed a device for field-testing strength of CEBs.
• Aaron Crandall and Hervé Sivuilu worked on architectural drawings and details.
• Benja Farber studied carbon footprint and material sustainability.
• Molly Lyons created an energy model comparing the control house to the proposed CEB house.
• Adam Rodman created a cost estimate based on local Oklahoma subcontractors.
• Matthew Reyes studied the logistics and schedule of block production.
• Mitch Johnson researched mechanical, electrical, and plumbing coordination.
• Ryan Moheb determined the anticipated achievable points for NGBS certification.
• Peter Everest studied CEB wall assembly moisture control and site drainage.
• Tim Russell organized the sequence of data collection and testing requirements.

Each student topic was integral to the entire team’s understanding of CEBs. Students worked independently on their own topics and also together to manufacture blocks and build test walls. They were encouraged to go outside their academic comfort zones and think critically about their classmates’ research, which ultimately led to a better understanding of project goals.

Summary/Accomplishments (Outputs/Outcomes):

• The team successfully built a garden and retaining wall for CCHFH as a proof of concept study.
• The CEB house will be identical to the control house in layout, area, and interior volume.
• A computer software energy study determined the proposed CEB house will use less energy to heat and cool than the existing conventionally framed house on the adjacent lot.
• Another computer software program determined the CEB house will contain less embodied energy and be more sustainable than the existing conventionally framed house on the adjacent lot.
• The CEB house is designed, scheduled, detailed, and mockup walls are being built to ensure ease of construction.
• Based on the current design and proposed construction methods, the CEB house will qualify for silver certification according to NGBS.
• The cost of the CEB house will be comparable to the existing conventionally framed house on the adjacent lot.
• The CEB team tested various soil additives to create CEBs capable of structural capacity similar to conventional masonry units and uniform stability when exposed to moisture. They determined portland cement is optimal for this type of construction in a 6% by weight ratio in the soil mix and therefore will be used as a stabilizer.
• The team developed a testing apparatus to field test CEBs and ensure quality control at point of manufacturing.
• Calculations determined the CEB house will have sufficient strength for gravity loads.
• Testing determined the CEB walls without reinforcing do not have the required shear strength to resist earthquake loads prescribed by the International Building Code and thus requiring vertical reinforcement. The team chose geo-fabric reinforcement to sufficiently increase the strength of the walls for lateral loads.
• Many architectural and constructions details such as cladding attachments, openings, flashings, CEB connection to foundation, roof connection, etc. were explored and solutions were determined and detailed in the construction documents.
• The logistical process of making CEBs has been examined and practiced to achieve accuracy and increase efficiency.

Conclusions:

During Phase I, the team identified and solved many problems that will be faced in the construction of the CEB house. Tests and results from structural loading, energy use projections, soil mix design, lintel spanning, plumbing connections, CEB 3-point bending tests, and many other structural and aesthetic concerns all contribute to the team’s confidence the home will endure the test of time and be a beacon of environmental consciousness in our community. The overall concept is to provide safe, affordable, and sustainable housing for the masses.

Journal Articles:

No journal articles submitted with this report: View all 4 publications for this project

Supplemental Keywords:

Alternative Construction Material, Earthen Construction, Earth, Sustainable, Sustainability, Architecture, Affordable Housing

Relevant Websites:

AECT CEB machine manufacturer Exit
Smithsonian Magazine Exit
With Ancient Arches, the Old is New Again Exit
NM Adobe Code Exit
Picasa page of photos Exit

P3 Phase II:

Comparing the Sustainability of a Compressed Earth Block House to a Conventionally Framed House Built to National Green Building Standards  | 2013 Progress Report  | Final Report