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Green building has become a major fixture of the building landscape. In order to maintain
market competitiveness, post frame professionals should be aware of the green attributes
associated with post frame construction. Since there are few green building professionals
knowledgeable about post frame construction, it is important for post frame professionals to
communicate these attributes. Aside from being a strong, lightweight, and efficient form of
construction, post frame DOES qualify for green building credits based upon several attributes
associated with the post frame building system itself. Green attributes are demonstrated in the
areas of site specification, materials efficiency and energy efficiency. This white paper explains
many of the concepts of green building, the evolution of green building certification systems,
and specific features of post frame construction that can qualify as green building methods.2
Putting the ‘Green’ Into Post Frame:
Accounting for Post Frame Construction in Green Building
Certification Systems
Green building has become a major part of the building landscape. The value of green
building is expected to increase to between $96 and $140 billion by 2013 (McGraw Hill
2009). According to a recent study by Good Energies, Inc., half of all non-residential
building stock will consist of green buildings by 2015 (Wall Street Journal 2010). Many
groups touting green products and services have sprouted recently. However, the term
‘green’ is unclear in meaning and impact. It is difficult to navigate through these various
claims, products, and systems. Green building, in particular, has several definitions
which are very broad and can be interpreted in a variety of ways. It is often more
valuable to examine the purpose of green buildings – which is to create a safer, more
efficient structure for both humans and the environment.
Post frame construction has always been considered an efficient building system.
However, the majority of green building certification systems have been created with
conventional wood construction, steel moment frames or monolithic concrete building
systems in mind. Efficient building systems are often not accounted for in many of the
green building certification systems. Unfamiliarity with post frame construction places
responsibility for justifying the green building potential upon the post frame builder and
design professionals. The purpose of this white paper is to provide tools for the post
frame industry to better interpret and use green building certification systems to
demonstrate the value of post frame construction. Post frame construction should be
considered a ‘green’ building system.
This white paper is the first in a series on the topic of green building in post frame
construction. This paper provides a short introduction to post frame, basic terms,
history, and concepts associated with green building, and the applications of green
building to post frame buildings including the key green building elements related to 3
post frame construction. Subsequent white papers will explore particular green building
certification systems applied to post frame.
Introduction to Post Frame Construction
Post frame construction has been used since the 1930s for a large variety of structures.
Originally begun in the agricultural sector, the efficiency of post frame construction
resulted in part from material scarcity. The basic system of posts embedded into the
ground, a truss roof system and a building skin capable of transferring shear forces has
been continually refined over the years. Material innovations including alternative post
foundation systems, preservative pressure treated lumber and wood composites
including glued laminated timber, nail laminated wood assemblies, laminated veneer
lumber, and parallel strand lumber have been incorporated.
Definition of Green Building
Green building certification systems are a manifestation of the larger concept of ‘green
building.’ Green building has many definitions that are very broad and allencompassing. According to ASTM E 2432, green building is a “building that provides
the specified building performance requirements while minimizing disturbance to and
improving the functioning of local, regional, and global ecosystems both during and after
its construction and specified service life” (ASTM 2009). According to the 2008
California Green Building Standards Code, green building is “a holistic approach to
design, construction, and demolition that minimizes the building’s impact on the
environment, the occupants, and the community” (ICC 2009). Neither of these
definitions are particularly helpful in explaining what IS or IS NOT green building, (e.g., if
a building is not green does it, by definition, NOT meet specified building performance ,
or are non-green building ALWAYS injurious to the environment?). Green building can
be summarized as making decisions on material efficiency, energy efficiency, water,
and safety of the occupants and surrounding environment. These particular decisions
are complex and intertwined. Green building has no one single optimized answer to the
particular qualities a structure should have. For instance, changes in the amount of
material used in the structure often offset energy needs to heat and cool the structure, 4
so that optimum energy efficiency and optimum material efficiency may be mutually
exclusive.
Several tools have been presented to illustrate the different choices and help make
value-based decisions. The ecological footprint is a measure of how much land or
space would be needed in order for a product or structure to be considered sustainable.
The ecological rucksack is a measure of how much material must be transported to
create a particular product or structure. A more rigorous process is the life cycle
analysis, which accounts for the material and energy inputs and outputs through the
stages of material extraction, manufacture, use and deconstruction. While all buildings
require energy and materials for construction, these tools allow comparisons of different
building methods, subsystems and materials to be made. In most of the green building
certification systems, a priority is placed upon energy efficiency and indoor air quality. A
further concept in green building is the net zero energy building, where the building
produces enough energy to meet or exceed the operational requirements of the
building.
History and Concepts of Green Building
The driving force behind green building has been the environmental movement in the
United States. While many environmentalists in the 1960s through 1980s focused on
governmental and industrial pollution, the environmentalism of the 1990s and 2000s has
shifted to the individual pollution contribution by personal use of energy and materials,
as well as the creation of greenhouse gases. Buildings use 40% of all extracted
materials in the United States and consume approximately 72% of electricity produced
in the United States (EIA 2008). By improving efficient construction and reducing
energy use, there is a large potential to save energy and reduce pollution. As a
population, the United States spends 90% of time indoors (US EPA 2009), making the
quality of air in structures a primary health concern. Some reports have stated that
indoor air quality may actually be worse than outdoor air quality.
Another concept that contributed to the development of green building was the idea of
sustainability. The Brundtland Report defined sustainable development as meeting “the 5
needs of the present without compromising the ability of future generations to meet their
own needs” (WCED 1987). Sustainability has inspired the concept that humans can
improve the environmental health of a site through buildings and construction.
Leadership in Energy and Environmental Design (LEED)
As a result of many of these ideas, the United States Green Building Council (USGBC)
was formed in 1993 as a non-profit organization to promote sustainability in the design,
construction and operation of buildings (www.usgbc.org). This group developed what
was considered the first green building certification system called Leadership in Energy
and Environmental Design (LEED). LEED was originally applied to commercial
structures, but the current 2009 LEED program contains a suite of green building
certification systems including homes, neighborhood development, commercial interiors,
core and shell, new construction, and institutions, which includes schools, retail, and
healthcare.
A green building certification system is a set of building and construction practices
considered to contribute to creating a green building. Various point values are assigned
to these practices and the accumulation of enough points results in the recognition of a
certified green building. Various levels of achievement depending on points accrued
can also be achieved. For the LEED system, the certified level is the base green
building considered, while Silver, Gold and Platinum levels represent higher levels of
certification. The LEED system contains a series of green building certification systems
for different building uses and types. Many companies, universities and municipalities
have adopted the LEED standards for all new construction. Two of the most important
LEED certification systems for post frame construction are LEED New Construction,
and LEED for Homes. Topics included in the LEED systems include Sustainable Sites
(SS), Water Efficiency (WE), Energy and Atmosphere (EA), Materials and Resources
(MR), Indoor Environmental Quality (IEQ), Innovation in Design/Operation (ID or IO),
and Regional Priority (RP). 6
The Green Building Certification Institute (GBCI) has also developed an accreditation
program for engineers, architects and building professionals (www.gbci.com). To begin
the process of applying for a LEED building requires the involvement of a GBCI-trained
professional. Previously, these professionals were identified as LEED-AP, or accredited
professionals, but changes in the accreditation system in 2009 include the designations
LEED Green Associate and a series of LEED-AP designations for the different type of
construction studied.
The progress of green building and the LEED system have not been without
controversy. Many of the practices chosen as ‘green’ were perceived to have green
building effects, but may not. One of the most contentious issues is related to the use
of wood and wood products. Currently, LEED applies a credit for certified wood
products using only the Forest Stewardship Council (FSC) certification program. FSC is
one of a number of forest certification programs and is seen as one of the most rigorous
in terms of documentation, especially documentation which does not directly relate to
the processing/manufacturing of the wood products themselves (community
involvement, labor practices, illegal logging, etc.). At the current time there is no
certification process for steel, concrete or rapidly renewable materials such as bamboo.
Rapidly renewable materials are another contentious issue due to the lack of
sustainable production in favor of quick growth. The lack of certification programs for
these materials seems to hold wood and wood products to a higher standard than other
building materials. Many members of the wood products community are frustrated by
this discrimination given that wood is the only renewable structural material in common
use. Other issues with LEED do exist, such as the reluctance to adopt a life cycle
analysis tool in the certification process.
Another green building certification system, the Green Building Initiative (GBI) promotes
the use of the Green Globes green building certification system in the United States
(www.gbi.org). Green Globes is a certification system for commercial construction.
This system is often seen as a more user-friendly system compared to LEED in terms of
defining construction practices. Green Globes is probably best noted for its use of life 7
cycle analysis (LCA) in the choice of green building materials. LCA for Green Globes
uses the ATHENA Institute’s Impact Estimator for Buildings available free online at
www.athenasmi.org/tools/impactEstimator/. Categories within the Green Globes system
include Energy, Indoor Environment, Site, Water, Resources, Emissions,
Project/Environmental Management.
While the LEED home rating system was only published in 2009, another green building
system sponsored by the National Association of Home Builders (NAHB) has taken
prominence in the residential construction area. The National Green Building Standard
is an ANSI-approved standard for the construction of residential green buildings
administered by the International Code Council, the authors of the IBC and IRC (ICC
2008). The previous document, which was the predecessor of the National Green
Building Standard, was the NAHB Green Scoring Tool. The ANSI standards process
requires the National Green Building Standard, designated ICC-700, to conform to
certain practices and maintain a consensus-based process for amendments and
changes. The National Green Building Standard consists of seven areas including Lot
Design, Resource Efficiency, Energy Efficiency, Water Efficiency, Indoor Environmental
Quality, Homeowner Education and Global Impact. A building must conform to green
practices in each category to obtain a minimum point value to be considered a green
building in this system. The National Green Building Standard differs from LEED in the
definition of building practices and specific construction recommendations rather than
more broadly defined conceptual goals. Categories for the National Green Building
Standard include Lot Design, Resource Efficiency, Energy Efficiency, Water Efficiency,
Indoor Environmental Quality, and Operation Maintenance and Building Owner
Education.
International Code Council Contributions to Green Building
A further addition to green building has been contributed by the International Code
Council (ICC), the authors of the International Building Code and International
Residential Code. The ICC Evaluation Service has begun the Sustainable Attributes
Verification and Evaluation (SAVE™) program. The SAVE™ program produces
Validation of Attributes Reports™ (VAR™) which provide third party verified sustainable 8
attributes of building products. The VAR™ identify sustainable attributes, while
evaluation reports (ESR) from the ICC-ES provide engineering and building science
data.
The VAR™ includes volatile organic compound (VOC) contents, as well as percentages
of recycled materials. SAVE™ is intended to be a clearinghouse of sustainability
criteria from manufacturers in an easily accessible, online location to help improve the
use and validation of green building products. The SAVE™ program
(http://saveprogram.icc-es.org/) provides standard sets of test criteria and also is a
preventative measure against “green-washing”, or the unclear or unverifiable
statements related to sustainable attributes. Other systems have begun to grow,
including a similar system from TECO (http://verified.tecotested.com/verification), and a
database from the National Association of Home Builders
(http://www.greenapprovedproducts.com/) listing green-approved products for the
National Green Building Standard. These product verification standards are important
to insure that different green building certification systems (LEED, Green Globes,
National Green Building Standard) conform to standardized, quantifiable measures of
sustainability for the materials used.
In a further move by the ICC, the International Green Construction Code (IGCC) has
recently been posted for public comment. The IGCC should be available for adoption in
the first quarter of 2012. This document is targeted towards commercial construction,
whereas the National Green Building Standard was focused on residential construction.
This document represents a significant step by ICC to help develop a standardized set
of principles and building practices which can be identified as green building. The
standard can be accessed at http://www.iccsafe.org/cs/igcc.
Proliferation of Green Building Systems
Aside from the green building certification systems mentioned so far, a variety of local
and regional systems have begun, including Earthcraft Virginia (www.ecvirginia.org),
Earthcraft (www.earthcrafthouse.com), Built Green (www.builtgreen.net), MN Greenstar
(www.mngreenstar.org), and Alliance for Environment and Sustainability 9
(www.alliancees.org). Most of these systems focus on single or multifamily housing.
Some of these systems refer to LEED or the National Green Building Standard as
parent documents and then contain customized information for a specific locality.
Post Frame Construction Contributions to Green Building
The concepts of green building embedded in the various green building certification
systems have been previously discussed. These green building certification systems
have particular assumptions about buildings and construction which may not completely
correspond with post frame construction systems. This section discusses some basic
characteristics shared by the majority of post frame building system. In order to be
considered a green building from any of the green building certification systems, the
building will need credit for other green building features. Three areas which the post
frame building system impacts green building are the site specification, material
efficiency and energy efficiency. Additionally, many green building certification systems
provide credits for innovative design and operation.
Site specification
• Minimize soil disturbance and erosion – Post frame construction requires minimal
soil disturbance in most cases, since only post holes need to be dug. Further
credit for this reduction in soil could also be obtained in some ‘Innovative
Solution’ sections.
• Reduce Local Heat Island Effects – Due to the limited soil disturbance for posts,
there is less possibility that current trees and shrubs on the site need to be
disturbed in order to construct the building. By providing shade and vegetation
around the structure, the ‘heat island’ effect, attributed to heat radiated from
buildings and surrounding man-made materials, is mitigated.
• Pest Control – the use of termite barriers and preservative pressure treated
(PPT) lumber prevents long term decay of a building. Additional points may be
gained for use of certain PPT that do not contain arsenic or pentachlorophenol.10
Material Efficiency
Typical post frame construction uses a system of posts and trusses. The structure is
also engineered with a specific documentation of framing elements and cut lists. Since
little site cutting is needed for these materials, post frame construction contributes to
several of the following areas:
• Lower Framing Material Waste
• Detailed Framing Documentation
• Cut List for Lumber
• Offsite Fabrication (NOTE: Some systems require ALL components to be
panelized / constructed offsite for this credit)
In addition to these credits, post frame far exceeds what are termed ‘Framing
Efficiencies’ which are usually realized by spacing 2×4 or 2×6 studs in a wall up to 24
inches on center. The purpose of this credit is to allow larger spaces for insulation and
reduce thermal breaks. Additionally, post frame wall systems offer a great reduction in
the amount of concrete needed for securing the post or a pier system compared to a
continuous frost wall with footings.
Energy Efficiency
• Exceed IECC insulation – The large cavity created in post frame walls allows for
a higher level of insulation than recommended by the International Energy
Conservation Code (IECC). Based upon current IECC calculations, filling the
cavity with most types of standard wall insulation should provide this level of
compliance. This finding should be confirmed with actual energy calculations of
the structure.
• Reduced Envelope Leakage – With fewer wood elements in the exterior walls
and more insulation coverage comes the potential for reduced envelope leakage.
This finding should be confirmed with actual leakage measurement of the
structure.11
Conclusion
The green building movement is predicted to grow and become a major force in
construction. Post frame buildings contain many features as a building system that
make them inherently green. However, most of the green building certification systems
do not comprehend these advantages of post frame construction. Post frame
construction causes less site disturbance, uses materials more efficiently and creates
larger insulation cavities to promote energy efficiency. These advantages create more
resource and energy efficient buildings, which is the goal of green buildings. Post frame
professionals must be able to interpret and communicate the advantages of post frame
for green building use to make post frame construction more marketable.
Acknowledgements
This white paper was assembled with the involvement of members of the NFBA
Technical and Research (T&R) committee.
References
ASTM. 2009. ASTM E 2432-05 Standard Guide for General Principles of
Sustainability Related to Buildings. American Society of Testing and Materials. West
Conshohocken, PA.
CIB. 1994. First International Conference on Sustainable Construction. Conseil
International du Batiment. November 6-9, 1994. Tampa, FL.
EIA. 2008. EIA Annual Energy Outlook. Environmental Information
Administration. http://www.eia.doe.gov/aer/pdf/aer.pdf. Accessed on January 15, 2010.
GBCI website
ICC. 2009. 2008 California Green Building Standards Code. California Code of
Regulations, Title 24, Part 11.
http://www.documents.dgs.ca.gov/bsc/2009/part11_2008_calgreen_code.pdf.
Accessed on January 20, 2010.
ICC. 2008. National Green Building Standard. ICC 700-2008. International
Code Council.12
McGraw Hill. 2009. Green Outlook 2009: Trends Driving Change. McGraw Hill
Construction.
NAHB. 2009. www.nahbrc.org. Accessed on January 15, 2010.
U.S. EPA. 2009. The Inside Story: A Guide to Indoor Air Quality.
http://www.epa.gov/iaq/pubs/insidest.html. Accessed on January 15, 2010.
USGBC website. www.usgbc.org. Accessed on January 15, 2010.
Wall Street Journal. 2010. “Half of Non-Residential Buildings Will Be Green by
2015 – Study” January 6, 2010. http://blogs.wsj.com/venturecapital/2010/01/06/half-ofnon-residential-buildings-will-be-green-by-2015-study/tab/print/. Accessed on January
20, 2010.
WCED 1987. World Commission on Environment and Development. Our
Common Future. Oxford Press. New York. p.8.
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