Quantifying post frame’s sustainability
By Daniel Hindman, PhD.
Green building is one of the most dynamic market forces in construction today. Post-frame buildings are considered sustainable, but until very recently little documentation existed on the energy efficiency and the reduced impact on the environment created by post-frame buildings. However, members of the Technical and Research Committee of the National Frame Building Association have developed life-cycle analysis (LCA) and life-cycle costing (LCC) tools to account for post-frame construction’s sustainable attributes.
“Green building” is based on producing more sustainable buildings and is the basis for green building certification systems such as the Leadership in Energy and Environmental Design suite of programs, Green Globes, National Green Building Standard and the International Green Construction Code, which is currently under review. These certification systems encourage many building practices including the use of recycled, regionally produced and rapidly renewable materials.
Current methods of post-frame construction contain many green elements, including
- reduced site disturbance
- less use of wood to create the structural system
- engineered systems for the roof structure
- a building cavity with room to accommodate insulation to meet International Energy Conservation Code requirements — a must for many green building systems
- flexibility of interior design due to the absence of interior structural columns.
LCA. One area of study to help support the claims of post-frame construction as a green building method is the building’s life cycle — a collection of all inputs (materials and energy) and outputs (product, waste, emissions) required by a structure for the intended service life of a building. The IGCC, the National Green Building Standard and Green Globes include a whole-building LCA as an elective, but at this time no green building certification system requires it. It’s important to note, however, that green building systems are constantly undergoing evolution and growth, and the need to document the environmental effectiveness of buildings will only continue to increase.
Although many whole-building LCA software packages exist, post-frame buildings are not currently included in any of these programs as a building type. A spreadsheet tool, which will be available on www.PostFrameAdvantage.com and the NFBA website (www.nfba.org) in coming weeks, features an equivalent conventional wood-frame structure with modified material inputs to create an analogous post-frame structure. In the tool, three building examples are included — a residence, a large church addition and an unconditioned storage facility — to demonstrate how the spreadsheet and post-frame building components can be integrated into different building designs.
LCC. LCC is a method to determine the entire cost over a product’s intended life cycle. For buildings, the main factors considered are initial cost, operating costs, replacement costs and maintenance or repair costs. LCC is an economic assessment that includes detailed energy modeling of the structure. LCC does not include environmental impacts of the building and is not currently included in any of the green building certification systems.
The main use for LCC is as a purchasing tool for predicting the expected costs of a structure, rather than focusing only on the initial construction costs.
These life-cycle tools allow the assessment of the environmental impacts of post-frame building systems and give green building professionals more tools for building evaluation. Architects should be aware that, in many building projects, post-frame systems can reduce the amount of structural materials used compared to other building systems. FBN
Daniel P. Hindman, PhD, is associate professor of Wood Science and Forest Products at Virginia Tech. The January 2010 white paper, Life Cycle Analysis and Life Cycle Costing Tools Applied to Post-Frame Construction, is available on www.PostFrameAdvantage.com. Hindman can be reached at firstname.lastname@example.org.