Government at all levels has long been asking citizens to embrace energy efficiency, from promoting recycling to encouraging residents to use their cars less and use energy-efficient light bulbs. Those communities also are demanding more from their state and municipal leaders-energy-efficient buildings constructed according to enforceable, safe and sustainable building codes that complement LEED and other rating systems.
The International Green Construction Code is answering the call, and it will impact metalbased construction.
The IGCC, developed by the International Code Council in cooperation with construction industry associations representing architects, engineers, green building and illumination, is an enforceable building code designed to drive safe and sustainable construction practices. It will improve the long-term performance of new and existing commercial and residential buildings. The code complements existing voluntary rating systems by establishing new requirements for “green” construction within a jurisdiction that adopts the codes. The IGCC is coordinated with ICC’s extensive family of construction codes.
Although the IGCC is not a rating system, it incorporates an innovative new concept, project electives designed to encourage and drive the construction of buildings that exceed minimum code requirements, much like rating systems do. It contains features that allow jurisdictions to customize and tailor the code to address sustainability and performance concerns at a local level.
For metal-based construction, energy-efficient design and materials feature prominently as the IGCC focuses on specific areas such as material selection, insulation and roof selection (see sidebar).
The IGCC requires 55 percent of the building materials meet either a minimum percentage of the materials to contain a minimum percent of recycled content; the materials be manufactured such that at least 30 percent can be recycled or recovered later; or use materials or bio-based materials (Sections 503). Most steel structures will likely satisfy this requirement, given their highly recycled and recyclable composition. While such a stipulation may not fundamentally change the materials used in construction, jurisdictions where the code is adopted are going to want proof that the materials being selected and later installed meet that section of the code.
When it comes to the challenge of increased insulation that many metal structures require to meet and exceed efficiency standards, the IGCC offers accommodates for eight climates zones. This piece of the code stipulates how much insulation is needed based on the temperatures and humidity levels in each zone. The insulation requirements are intended to keep better control “on the seams” to keep energy from leaking and resulting in increased efficiency.
The roof of any structure has the potential to be inefficient-allowing cool air to escape and heat to be absorbed. The IGCC provides guidelines to solve those problems by requiring the use of surfaces that are absorbent, reflectant or painted with carefully chosen colors to control heat island impact. Materials common to buildings and roads and site development will absorb and retain heat more than farmland or undeveloped land such as forests. As a result cities develop a ‘heat island’ that impacts the local climate. Enough heat island build-up and it takes more effort to cool buildings. Vegetative roofs can also be used to absorb heat in certain situations (see sidebar).
The IGCC will have a direct and positive impact on communities’ efforts to create healthier environments. For example, it requires that builders reduce construction waste in materials and that at least 50 percent of construction phase waste materials be diverted from landfills. These standards apply to on-site construction, as well as to the manufacturing of materials. Water conservation efforts continue to be a focus of the code throughout the life of the building, as facilities managers are encouraged to use graywater for irrigation, for example. This section of the IGCC may be particularly useful in areas where water must be used strategically, such as in the Southwest.
While IGCC requires the typical commissioning, it also promotes enhanced inspection to measure energy efficiency. Those inspections are conducted at various points during the process, including before and after the building is occupied. One of the goals of commissioning is to ensure that actions such as sealing the building and HVAC systems are doing what they are designed to do-essentially serving as a check on the design. This is required before a building is given its certificate of occupancy.
Under Section 304 and the whole building life cycle assessment, the CO2 emissions may need to be assessed and documented if global warming is included as a component of the review criteria. However, this is not a mandatory requirement, but a good example of the built-in flexibility provided by the code.
The IGCC also weighs quality of life issues when considering energy efficiency, taking occupants’ comfort and efficiency into consideration, for example, when it requires the presence of natural light via skylights or windows. This standard represents a shift from building codes of late, which have focused on structures that have fewer windows to keep energy from leaking out of them.
Several jurisdictions have already adopted Public Version 2.0 of the code due to its adaptability, enforceability and ability to lay a foundation for more sustainable communities. Adoptions include including Maryland, Rhode Island, and communities in Arizona, Colorado and Washington.
There will be opportunities for members of the metal design community to comment on the code in May at Code Development Hearings in Dallas and the Final Action Hearings in November 2011 in Phoenix. The final version of the IGCC is slated to roll out in early 2012.
The code’s cooperating sponsors are the American Institute of Architects, ASTM International, the American Society of Heating, Refrigeration and Air Conditioning Engineers, the U.S. Green Building Council and the Illuminating Engineering Society.
Insulation
The focus of the IGCC is to increase the long term performance of structures and as part of that goal, sections such as insulation are especially critical to metal building developers.
Structures built using metal frames are susceptible to having heat flow through metal studs and joists. Because of this difference, structures often times need to place continuous insulative sheathing over the outside of the wall frame and between the metal framing pieces in order to maximize energy efficiency. The IGCC addresses this unique need for metal structures in the areas of materials selection and insulation by requiring:
Materials Selection
- No less than 55 percent of the total building materials either be used, recycled content, recyclable or bio based materials
- Requires contractors to document the origins of the materials used, as well as its recycled content
Insulation
- Requires increased insulation to mitigate heat loss of metal structures
- Varies based on the temperatures and humidity levels in each climate zone
- Roof Selection requires the use of surfaces that are absorbent, reflectant or painted with carefully chosen colors to control heat island impact
- Options for vegetative roofs to absorb heat Sections 607 and 806 of the IGCC provide more details on insulation for the building envelope.
Vegetative Roofs
Rising energy costs and the need for increased energy efficiency are two main drivers behind most high performance building efforts such as the IGCC. A third driver of equal importance is to reduce the long term impact of building construction and use on the environment. All of these drivers are also behind the development of vegetative roofing.
Vegetative roofing has the potential to reduce heating and cooling costs in addition to reducing usage of peak electricity, controls ambient air temperature and reduces drainage runoff. One of the best things about the roofs is that they can be developed with very little experience by the owner of the structure, but when it comes to creating a good structural foundation the IGCC provides the footing to make for a successful vegetative roofing project.
There are many areas of the IGCC that cover vegetative roofs and even roofing options that are specific to metal structures. Those areas covered are in the extensive and intensive vegetative roofs and metal roofs section (406.7):
- Requires the use of surfaces that are absorbent, reflectant or painted with carefully chosen colors to control heat island impact
- Not less than 75 percent of the roof surfaces of buildings located in climate zones 1 through 3, as established in the IECC, shall be in compliance with Section 404.3.1 or 404.3.2, or a combination of both methods.
- In climate zones 4 through 8, as established in the International Energy Conservation Code (IECC) the development of a new building with roof coverings in accordance with Section 404.3, shall be recognized as a project elective.
- All plantings shall be selected according their United States Department of Agriculture hardiness zone classifications and shall be capable of withstanding the climate conditions of the jurisdiction and the micro climate conditions of the building site including, but not limited to, wind, precipitation and temperature.
- Protection measures include, but are not limited to, installation of pre-grown vegetated mats or modules, tackifying agents, fiber blankets and reinforcing mesh.
Kermit Robinson is senior technical staff at the International Code Council, Washington, D.C. For more information on these sections of the IGCC, go to www.iccsafe.org/igcc and download a free copy of Public Version 2.0.
