Materials & Resources
Recycled and Rapidly Renewable

As for recycled content, there is traditionally a small amount of post-consumer material used in typical ceramic tile manufacturing, including post-consumer glass and remilled waste from fired tile—a product called chamotte. One reason these waste streams are employed is to enhance the technical or aesthetic value of the tiles. Yet the process tolerances are high—ceramic tile requires high-grade component resources to achieve its high level of performance in terms of resilience, compressive strength, scratch resistance, and the like. Another reason is that tile is traditionally seen as a long-term installation—lasting decades, as opposed to the several years commonly associated with carpeting, for example.

The real benefit for a closed-loop cycle comes from the efficient manufacturing processes developed in Spain and other industrial centers of tile production. To be competitive and protect the environment, tile makers recycle water and post-industrial waste—not only within-the-fence but also among nearby producers in industrial clusters such as in Castellón, Spain. Closed-loop manufacturing processes, used by the vast majority of makers, capture vast amounts of suspended clays and minerals in production water, a residual raw material as good as the virgin source. Waste tiles, such as those broken or at the ends of useful production runs, are sorted and binned for reuse.

Under LEED credits MR 4.1 and MR 4.2, only 50 percent of the preconsumer waste may be applied toward a project's recycled content. Though it can help provide a LEED credit, this “half-off discount” for preconsumer as opposed to postconsumer waste, is a source of ongoing debate among experts in green building. The fact is that any recycled content diverted from the waste stream is of equal value—a point argued in the development of the IGCC (see sidebar “A New Look at Recycling”).

Other ceramic tile manufacturing processes provide for valuable environmental benefits. Typically about 94 percent of the production water is reused. Ceramic tile manufacturers also conserve energy through closed-loop heat recovery and by using solar power as well as cogeneration, in which electricity and useful heat are captured simultaneously. Again, the sharing of energy sources by clustered industrial villages increases the scope of this efficient ecosystem.

Similarly, the benefits of rapidly renewable materials as outlined in MR Credit 6 – Rapidly Renewable Materials, is to “reduce the use and depletion of finite raw materials and long-cycle renewable materials by replacing them with rapidly renewable materials.” While this credit has been explicitly associated with plants such as wood, linseed, cork and bamboo with a short harvesting cycle of less than 10 years, many experts recommend that the credit be expanded to include “perpetual resources”—materials with no reasonable chance of depletion, according to the Environmental Economics Organization.

Examples could include salt, magnesium, the silica (sand) used to make glass and the feldspar and clays used for ceramic tile – materials that have a sufficient renewal rate given the vast reserves available and the installed product lifespan.

Ceramic tile is composed of sand, clay and feldspar; porcelain is made with quartz, kaolinic clay and feldspar. Geologists estimate reserves of these raw materials to be in the billions of tons. They are found on every continent and in many countries and are in no danger of depletion. Ceramic clay and kaolinic clays, proportionally the largest component resources for ceramic tile and porcelain tile, respectively, are not considered a rapidly depleting resource by any authority. “About half of the world's kaolin production is used by the paper industry for coatings and fillers,” says Fasan, adding that only about 15 percent is used for the production of ceramics.

In geological surveys of clay and feldspar reserves, scientists classify the base materials for ceramic tile as perpetual resources, with no potential for significant depletion even with the population growth and increased demand expected for the next 350 years.

Sustainable Sites and Sustainable Buildings

Ceramic tile provides additional benefits for green building projects, some of them included in the LEED framework. Under Sustainable Sites (SS), there are two credits for heat-island mitigation applying to roof and non-roof exterior areas. These credits reward the minimizing of surfaces that absorb and retain heat, a reduction beneficial to humans in developed microclimates and to nearby wildlife habitats. The use of light-colored tile on building surfaces and site hardscape areas has a significant capacity to reduce heat islands.

According to Lawrence Berkeley National Laboratory, Berkeley, California, the key measures of a surface's ability to reduce heat built-up are reflectivity and emissivity. Solar reflectance index (SRI) combines both: As defined by the standard ASTM E 1980, SRI describes how well a surface “bounces away” solar radiation and radiates away (or emits) absorbed heat. Light-colored roofing and surfaces tend to have a good SRI; metallic surfaces tend to have low emissivity rates.

Exterior ceramic tile in a light color—with an SRI of at least 29—must cover at least 50 percent of the paved or finished outdoor surfaces, or hardscape, in order to earn the LEED credit. Roofing tiles must achieve a specified SRI over at least three-quarters of the roof surface.

Not only do these ceramic tile surfaces reduce heat-island effect—they also reduce building energy needs for heating, ventilation and air-conditioning (HVAC). That's one reason ceramic tile is valuable for the Energy & Atmosphere (EA) credits. Another is the use of ventilated porcelain façades, which can reduce building energy use up to 25 percent over comparable enclosure designs, according to Barcelona-based Roca Cerámica, one of Spain's larger tile producers.

Another tile producer, Tau Cerámica of Valencia, Spain, has developed a PV tile façade system with Madrid-based PV company Atersa. The system adds building-integrated PV production to the same ventilated tile rainscreen concept, bringing architects closer to a net-zero-energy solution without requiring a special armature for the PV system. All of the tiles are attached with the same frame system.

Innovation in Design and Life Cycle

The novel, net-zero design approach using BIPV panels is not the only unique tile-related concept that has led to Innovation in Design (ID) credits through the LEED certification system. Other product and system innovations have included ventilated façade systems combining porcelain tiles and vegetated panels.

Even the basic material innovations of recent years—notably the use of simulated wood grains or metal finishes rendered in glazed ceramic tile—provide ways to create attractive, safe, and durable building features. Imagine, for example, a pool deck that looks like a dark grainy maple plank yet is actually composed of large-format ceramic tile. The look is lasting, and the finish choice will last as much as four times longer than the real wood alternative.

In this way, this innovative material selection also directly impacts the product's LCA: While wood planks might have a lower installed first cost, the more durable and lasting surface may provide better life-cycle performance. The better LCA should be a more “ecological” choice.