Volume 41, Issue 9 - September 2006

Green Machine
How Contract Glaziers Can Use Glass to Increase Their LEED Rating 
by Henry Taylor

Established in 1998, Leadership in Energy and Environmental Design (LEED) has come to the forefront of the building industry. It has been particularly well-seated in commercial construction, and the number of projects seeking LEED certification—or simply building in accordance with its guidelines—is increasing steadily. Members of the glass industry who understand the program components and are able to work within its strategies will be well- prepared for a growing market. 

Starting with the Basics
Created by the U.S. Green Building Council (USGBC), the LEED Green Building Rating System is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. USGBC’s members, representing every sector of the building industry, have developed and continue to refine LEED. 

LEED provides a framework or rating system for assessing a building’s performance in meeting green building practices and sustainable goals. This common standard of measurement is outlined in the LEED rating system, which has a possible total of 69 points spread over six major categories:

  1. Sustainable sites;
  2. Water efficiency;
  3. Energy and atmosphere;
  4. Materials and resources;
  5. Indoor environmental quality; and
  6. Innovation and design process.

The LEED certification process begins when the owner and design team register the project online with the USGBC. This formal registration declares the intent to build in accordance with green building practices and sustainable construction. Reviewing the design with the LEED 2.2 checklist, the design team and the owner must determine any issues and/or potential modifications that will need to be made in order to achieve points in each major category. Understanding the design team’s strategy will provide opportunities for contract glaziers to be a resource and offer solutions that achieve the common design goal. 

Energy and Atmosphere
Glass truly comes to the forefront in the energy and atmosphere category. There are a total of 17 possible points in this category, in which the design team must develop a strategy to improve the long-term operational cost and energy consumption of the project.

Once the project scope has been drawn, it becomes the “basis of design” (BOD). The BOD’s energy performance and requirements are determined by modeling the project in accordance with ASHRAE/IESNA Standard 90.1-2004 (without amendments).

Within this category are two important credits. First, optimized energy performance offers a potential of one to ten points, based on the percentage of improvement in energy consumption. Second, onsite renewable energy can earn the project up to three points, depending on the amount of onsite energy the project can generate. Both areas offer contract glaziers the opportunity to serve as consultants to their design teams, guiding them to options that can improve the performance of the glass and frames. 

Consider the following design issues:

  • Did the BOD use non-thermal frames? Switching to a thermally-broken system will improve the condensation resistance factor and U-factor of the frames.
  • Now offer the design team options in low-E glass and other high-performance coatings to improve the thermal performance of the glass.
  • What is the solar heat gain coefficient? How much heat is being permitted? All that heat requires greater demand on the HVAC system. 
  • Don’t forget warm-edge spacers. The greatest amount of heat loss is through the edge of glass. Argon and other gases also will slow heat transfer in cold climates.

Onsite renewable energy also provides a huge opportunity for the glass and glazing industry to play a role in generating points. The BOD’s annual energy cost is calculated, and one to three points could be awarded if it is proven that up to 12.5 percent of the energy requirements can be generated onsite. This can be achieved through wind, geothermal, low-impact hydro, biomass or solar systems, otherwise know as photovoltaic (PV). 

Building Integrated Photovoltaic (BIPV) is also growing in popularity. In Europe, for example, BIPV is standard in most commercial construction, and recently, there has been a surge of applications in the United States. In addition, this year federal tax laws in the United States were changed to encourage the utilization of PV through tax credits, and many states also offer tax incentives. There are even investment groups that will pay for the addition of BIPV in exchange for the tax credits and a percentage of the energy saving. 

Materials and Resources
There is a common misconception that LEED and green building programs primarily focus on recycled materials. While it is very important to reuse limited resources, LEED 2.2 only offers a total of two points in this area. 

There are two kinds of recycled content measured: post-consumer and pre-consumer. Post-consumer recycled content has lived its life expectancy in the market and is now being disposed of; it has already been consumed and its value as its original intent is gone. Pre-consumer recycled content was scraped during the manufacturing process and returned to begin the process over again. Most of the cullet in glass is pre-consumer, as is the aluminum in billet. Because it is difficult to control the contaminates entering the process from post-consumer material, the quality of the finished product suffers. 

For this area, the general contractor requests the percentage of each of these recycled types in the materials that the contract glazier is providing, as well as the weight and cost of these materials. Points will be awarded if the team shows that 10 percent or 20 percent of the value of the material used to construct the project consists of recycled material. 

If a glazier is bidding a project that has recycled content as one of its strategies, it must be noted upfront. Typically, the higher recycled content aluminum is not inventoried and needs to be ordered for the project. It adds to the lead time and cost as extra die changes may be required to extrude all the parts for one system out of higher recycled content billet.

Credits for use of regional materials are earned when materials that are extracted and manufactured within 500 miles of the project site are used. This is to support the local economy, utilize indigenous resources and reduce the environmental impacts of transportation. 

Projects that were registered under LEED 2.1 did not include the point of extraction within the 500-mile equation. LEED 2.2 added the point of harvesting or extraction within this requirement. It is difficult for both glass and aluminum products to meet this requirement since most of the raw material used to produce aluminum billet, for example, is mined in South Africa, Australia or Trinidad, just as the ingredients used to make glass also are manufactured in many different locations. 

Indoor Environmental Quality
One point is offered for incorporating natural ventilation of outdoor air into interior spaces. An easy way to earn this point is to add vents to a glazing system, either in the form of traditional operable vents or some type of passive ventilating mullion or sill in the frames. 

Points also are available when vents are incorporated into the glazing system near occupied areas. Studies show that workers are more productive when they have some control over their environments, such as being able to turn around and open a window. If a design team plans to incorporate these strategies, a contract glazier can make sure the designer understands what the industry is able to provide to ensure louvers are not used instead of vents.

Achieving these two credits for daylighting and views is made possible by opening up as much interior occupied space to natural daylight and outdoors views as possible, which means expanding the amount of glass on the building’s exterior. To reach the 90-percent mark, opening the core of the building under a skylight might be all that’s needed. Now punched openings become ribbon lites and ribbon lites might become curtainwalls to expand the glass surface and bring as much light in as possible. Contract glaziers might also suggest light shelves, which will bounce natural light deeper into a building. 

Since more glass also brings solar heat gain, sun shades should also be top of mind, as they are a fast and easy solution to that problem. Sunshades promote expanded glazing, while working toward optimized energy performance, a key element of the LEED rating system. 

LEED for the Glazier
As we’ve outlined, the glass and glazing industry is a direct part of three of the six LEED categories. Understanding and considering a designer’s strategy for achieving LEED points provides a great opportunity to serve as a consultant to the design team, to integrate and sell the right systems to enhance the project’s performance and value and to suggest the products and methods that will help achieve the project’s overall goals.

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