LEED BD+C: Homes v3 - LEED 2008
LEED Platinum 2012
Goals and motivations
What were the top overarching goals and objectives?
The project team and owner set up four areas of study at the outset of the project as guiding tenets.
- What kind of building science is introduced into the idea of a sustainable building?
- How to remediate previously industrial/commercial site and restore the ecosystem.
- Development and implementation of a paperless project using digital technologies
- Include findings in an education and awareness program and increase eco-literacy.
Photo by Harvey H. Kaiser
Looking across Snook's Pond at Snook's Hollow
The above tenets were manifested on the project by:
- Having the project serve as a model to demonstrate the economic and ecological value of sustainable residential construction for large homes. Ultimately the owners want to share the applicable derived design and construction principles learned on this project with the overall housing market.
- Utilizing ecological stewardship principles for maximizing sustainability. Employing advanced ecological techniques for the site and water resources (e.g., Snook's Pond Restorer System) to restore a previously developed site with hazardous waste and site contamination to a thriving site.
- Applying principles of net zero energy and carbon neutrality utilizing renewable energy and an enhanced thermal envelope and HVAC system, while providing improved indoor air quality, and use of environmentally friendly products
What were the most notable strategies used to earn LEED credits?
Compressed Construction Timeframe: The team exerted an effort to dramatically reduce overall time for project delivery by compressing design, procurement, and construction phases to improve efficiencies and a subsequent reduction in project costs, while optimizing sustainability features. This was done through regular team meetings, integrative design, and the use of digital technology to support communications between stakeholders and to minimize construction errors.
Integrated Project Delivery Team:An integrative process was utilized that included the owner, designers, material suppliers, contractors specialized expertise for ecological issues, and interior designers. This resulted in the achievement of a highly efficient project through all phases of design, procurement, construction, and post-construction. There are Quick Response (QR) codes accessible in every room to help with the operations and maintenance of the house.
Digital Technologies:We employed digital technologies to encourage seeking building and future operating economies, including Building Information Modeling (BIM), 3D modeling, and creating a digital jobsite to coordinate error-free installation of insulated concrete formed walls (ICF), timber frame roof, and structural insulated panels (SIP), and minimize construction waste material. This included minimizing the use of paper by having all design elements done digitally which reduced cost, waste, and delays.
Courtesy of Snooks Hollow LLC
The eight-inch thick structural insulated panels completing the high performance thermal energy envelope were cut precisely offsite using Building Information Modeling 3-D drawings.
Biomimicry:Several features of the site design addressed adaptively restoring and enhancing a degraded, polluted industrial site to functionally enhance and protect the living community surrounding Snooks Hollow. A total of 19 LEED certification points in several rating system categories are attributed to an ecosystem approach that included the irrigation water reduction design, employing rainwater harvesting and underground cisterns feeding a subsurface irrigation system controlled by moisture sensors. The intent was not only to reduce potable water on site use but to recharge the hydrology of the natural systems on site.
Applying Innovative Building Science:Adapt materials and methods of construction through the design and construction process for consistency with Snook's Hollow Vision and goals to achieve optimal performance of sustainability. Carbon neutrality was achieved by using renewable energy sources (geothermal, solar photovoltaic, and passive solar design). High energy efficiency resulted from a very tight thermal envelope. The floor slab is on a 12 inch thick R-50 rigid insulation; exterior walls are an R-56 rated sandwich of outside facing 6-inch thick styrofoam insulating panels, an 8-inch thick concrete panel, and a 2-1/4 inch thick interior foam insulation panel; and the roof system included 8-inch thick structural insulated panel.
Courtesy of Snooks Hollow LLC
Aerial view of entire house footprint with insulated concrete form first floor walls poured and prepared for placement of Quad-Lock concrete second floor.
Water use reduction:Gray water and captured rainwater is used as irrigation for the native species planted on site. Permeable surfaces were included wherever possible as the whole site was viewed as a long term reservoir for the native plants.
Aside from LEED certification, what do you consider key project successes?
A goal of the owner was to improve eco-literacy by dissemination of the project's successes. Many of the project's features indicated the possibilities for large houses to achieve high energy performance and carbon neutrality. The information collected during project development is proposed to be assembled and published in book form and presented to the design and construction industry and to owners with the support of the USGBC.
Another key success was the site assessment for ecosystem issues. A team of consultants from Cornell University were brought in to inventory all the native and non-native plant species on site. The ecological analysis identified what parts of the site should not be touched. For example, a mature sugar maple grove was identified and set aside as non-developable. The goals of the ecological assessment were to:
- Enhance the existing native species
- Reintroduce native species to the area
- Identify parts of the site that shouldn't be touched
Courtesy of Snooks Hollow LLC
Living room ceiling using recycled barn framing timbers.
One example of this is the white oak used in the roof timbers that came from Colorado. The ecosystem engineers advised that the owners plant a grove of white oak on the site and 100 - 200 years in the future there would be trees on site that could be cut selectively to repair any damaged timers in the roof. This illustrates the holistic and long term planning perspective that went into the ecological site assessment.
At the core of the project's development and implementation was team collaboration, guided by the integrative process. This approach was incorporated in all project phases that would stretch over a more than five year period, finishing with an intensive 11-month construction phase.
Rather than each participant focusing exclusively on their part of design and construction without considering the implications on the whole process, the Integrated Project Delivery (IPD) method brought all participants together early in the project as a project design team to maximize value for the owner. This collaborative approach allowing informed decisions to be made early in the project where the most value could be created by,
- Eliminating a great deal of waste in the design.
- Avoided development of adversarial relationships between designers and contractors.
- Allowed data sharing directly between the design and construction team eliminating a large barrier to increased productivity in construction.
The parameters set for the Snook's Hollow IDP team to guide the project through all phases had a core group composed of Owner, Architectural Designers, Interior Designers, and Contractor. The owners were a constant presence throughout the entire process joining with the following core group of companies and individuals actively participating in at least monthly, weekly, and daily project meetings, as necessary.
The IDP team continuously reviewed traditional design and construction processes, identifying flaws that created obstacles to achieving the project's goals. The formation of the IDP team was a key step in developing innovative processes, eventually achieving their LEED Platinum certification.
Courtesy of Snooks Hollow LLC
Drilling one of eight geothermal energy source wells at an average of 420 feet deep.
The compressed time schedule, required by the homeowners, was a challenging aspect of reaching the targeted LEED certification. Continuously reviewing ecosystem and building science innovations required time to ultimately select materials and construction methods intended to yield a high performance building. For example, using geothermal technology was compared to the house's thermal envelope and tradeoffs analyzed between the number of wells and exterior insulation. A decision to use an insulated concrete form system for all exterior and interior walls yielded insulating performance values that reduced the number of wells necessary by drilling and heat conversion equipment.
The lesson learned was to bring forth alternatives as early in the design and procurement process for comparative analysis and selection.
What was the value of applying LEED to this project?
The value of applying LEED to the project was the availability of a template for decision-making in all LEED categories. The structure of the LEED for Homes Project checklist enabled thoroughness in all project aspects such as,
- Determining sustainability of a process
- The method of construction or application of building science technologies
- The evaluation of materials for cost and scheduling implications, as well as performance of durability and resilience.
The integrative design process encouraged by LEED was critical to the success of the project and this extended to subcontractors as well.
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