Green Globes uses performance benchmark criteria, just as LEED does. However, one major benefit of Green Globes is that it compares building designs to data that reflects real building performance vs. the performance of hypothetical structures. It also encourages builders and designers to consider sustainability and green elements early in the project rather than adding expensive technologies later in the design.

Green Globes awards points for acoustical comfort, use of an integrated design process, emissions and effluents reductions and "minimal consumption of resources (reused, recycled, local, low-maintenance materials, certified wood) as well as reduction, reuse, and recycling of demolition waste." Using composite panels contributes to potential Green Globes points. For more information on the Green Globes rating system, visithttp://www.thegbi.com/commercial/greenglobes/index.htm.

Flame Spread Requirements for Composite Panels

Most code requirements for wood product interior finish materials are expressed in terms of flame spread index numbers. These values are determined in the standard U.S. flame spread test, ASTM E-84, conducted by such organizations as Underwriters' Laboratory and the Hardwood Plywood and Veneer Association.

Different maximum indices are permitted depending upon building occupancy, location of the material in the building, and the presence of sprinklers. The index is calibrated based on a scale where a noncombustible material is 0 and red oak flooring is 100. Class I or A designates flame spread range 0-25; Class II or B, flame spread range 26-75; and Class III or C, flame spread range 76-200.

Several composite panel manufacturers supply flame spread ratings for fire retardant products (Class I or A), which achieve that rating by using special treatments. Most wood products, however, including particleboard, hardboard, and MDF, are presumed to have a flame index of less than 200-class III or C-making them acceptable under current building codes for a wide range of interior finishes. Depending upon thickness, particleboard indices range from 145 to 156, and MDF indices range from 90 to 140. Indices for factory finished composite panels with vinyl or paper overlaid composite panels range from 100 to 180.

Some national and local codes require lower flame spread ratings. To meet those requirements, designers can specify specialty fire-retardant products from the handful of manufacturers who offer composite panels with a Class I or A classification.

Moisture Resistance

Because composite panels are mostly organic wood material, they are affected by the same environmental factors that affect timber and solid lumber and are therefore susceptible to water and moisture.

Moisture resistance is achieved through careful engineering to address two essential properties: resistance to dimensional change and retention of strength when exposed to water or elevated humidity. As a general rule, wood shrinks or swells in proportion to the volume of water lost or gained. When wood is green, it is saturated with water in both cell cavities and the cell walls. The water in the cell cavities is called "free water" and the water in the cell walls is called "bound water." Normally, free water is removed completely during the drying process. Some bound water remains and is in equilibrium with the relative humidity of the air. As the relative humidity of the air changes, the moisture content will correspondingly change. It can affect panel gluing, finishing, and dimensional stability.