I'm the board president of a Bronx cooperative, and we try to incorporate environmentally sound practices whenever possible in the operation and maintenance of our building. As part of that effort, we will be replacing our deteriorated roof with a green roofing system. We also will be undertaking other exterior work, including some limited brick replacement, balcony repairs, caulking, refurbishing the fire escape, and cleaning the facade. Are there specific methods and materials that our contractors should use when performing these repairs to ensure that the project is green friendly?
Non-toxic construction debris is separated on site and taken to facilities where it is salvaged and reused, not added to landfills.
As you undoubtedly are aware, the green building industry is growing by leaps and bounds, and an increasing number of materials and technologies are becoming available for improving the operating efficiency of buildings while reducing harmful effects to residents and the surrounding environment. With all the new sustainable products and practices on the market, however, it can be confusing to figure out which ones are beneficial and which offer more hype than hope.
Three main ways your building can incorporate environmentally friendly practices are 1) selecting recycled and/or recyclable green replacement materials; 2) using paints, cleaners, and solvents that are low in toxicity; and 3) recycling construction debris. Below is just a sampling of some of the green choices that your cooperative may wish to consider as it undertakes its repair and upgrade program.
Replacement Materials
Concrete Masonry Units: According to the Environmental Protection Agency, the production of Portland cement, the common ingredient in concrete masonry units (CMU), is the third largest source of greenhouse gas pollution in the United States. The fossil fuels used to generate heat in cement kilns releases large quantities of CO2, approximately one ton for every ton of cement produced. One line of sustainable CMUs uses recovered glass to replace up to 30% of the Portland cement content, offering the same advantages of conventional CMUs but with a less harmful environmental impact. Another advantage of sustainable CMUs: Their particles are smaller, reducing the size of the small voids typical in conventional CMUs, thereby reducing their permeability to water.
Wall ties, wires, and anchors: These steel reinforcing components for stone and masonry walls come in 95% or more recycled material.
Masonry flashing: One type of through-wall/surface-mounted flashing made from 45% recycled material consists of a composite membrane with an adhesive backing. The flashing, designed to resist tearing, can be applied to masonry, concrete, steel, and wood. Stainless steel reglets and termination bars, flashing components embedded in masonry joints, can be obtained with an average of 60% recycled content.
Recycling non-hazardous construction debris keeps it from ending up in landfills.
Insulation: One brand of sustainable insulation is a thin nanocomposite coating sprayed, brushed, or rolled on like paint onto an interior wall surface. Although it is more expensive than conventional fiberglass insulation, it requires much less labor to install than adding batt insulation (the rolled matted sheets) to existing structures. The nanoparticles used in the coatings repel water, resist mold, and are anti-corrosive on metal surfaces.
Bricks: Durable, weather resistant, and non-flammable, conventional clay bricks are a popular choice in building construction. Although clay bricks do not deplete a scarce resource and can be crushed and reused as gravel, they don't contain much recycled content nor can they be recycled into new bricks. In some cases, intact bricks from historic buildings can be cleaned and reused, but at an increased labor cost.
Sustainable bricks, which typically contain 30% to 100% of recycled material such as ceramic, glass, and iron oxides, are slowly making their way as a green alternative in the construction industry. Recycled bricks have many of the same advantages as clay bricks, but by reusing post-consumer material they add less to landfills. (Glass, for example, is not biodegradable.) In addition, recycled bricks manufactured close to where the materials are collected and processed also reduce fuel and emissions from transportation, lessening the impact to the environment even more.
Bear in mind, however, that sustainable bricks are not widely manufactured and therefore still limited in style, sizes, and colors. They are also usually not suitable for historic restoration projects, in which the brick has to closely match the existing in appearance. But as green technology matures in this area, expect a wider variety of options in sustainable brick to become available.
Reducing VOCs
One area in which a building can reduce its carbon footprint is by choosing materials low in volatile organic compounds. VOCs, which are emitted as gases and can be harmful to people and the atmosphere, are found in many building products and materials, such as paint and paint strippers (the strong fumes are VOCs), coatings, cleaners, fuels, wood preservatives, pesticides, and miscellaneous solvents.
Paints and coatings: Conventional oil-based paints contain high-levels of VOCs and require toxic solvents to clean up, releasing even more VOCs into the air. As an alternative, latex paints, which use water as a solvent, provide good quality and durability and allow for easier and less-toxic cleanup. Many low- or no-VOC stains and clear finishes for floors and cabinets are also commonly available.
A building can reduce its carbon footprint by choosing materials low in volatile organic compounds.
Facade Cleaners: Chemical cleaners, such as acid-based and alkali-based agents, are effective in removing dirt and stains from buildings. Applied improperly or in the wrong concentrations, however, they can discolor and/or damage masonry as well as leave hazardous materials in the run-off water after rinsing. As an alternative, biodegradable gel-based, latex-based, and water-based products, which do not contain harsh solvents or emit VOCs, can be used on most surfaces, including brick, concrete, metal, stone, and wood. Environmentally friendly cleaners may be painted or sprayed on and then stripped off, or in the case of paint-removal pastes, applied with a brush, roller, or spray and then scraped, squeegeed, or washed off. Not all cleaners (green or not) work on all types of masonry, stains, and dirt, so it's important for your contractor and engineer/architect to follow manufacturer guidelines to avoid scarring the building's exterior.
Caulking: Traditional caulking agents are applied wet, and as they dry and cure in place, many release VOCs, formaldehyde, and other products that improve performance and extend shelf life but may be harmful to breathe. Solvent-free caulking is available that emits minimal VOCs. These non-flammable, non-toxic products are also resistant to shrinkage and discoloration.
Construction Waste Management
The EPA estimates that more than 136 million tons of construction and demolition debris is generated in the United States each year. The construction documents for your building's upgrade project should specify that as much of the non-hazardous construction and demolition debris as possible must be recycled or salvaged. (Rand typically specifies a minimum of 50%.) This enables the recyclable resources to be re-manufactured, and it redirects other materials to sites where they can be reused, keeping the debris from ending up in landfills.
Construction waste typically consists of brick, concrete, metal, tiles, plastic, clean wood, glass, gypsum wallboard, insulation, carpet, and cardboard. Depending on the contractor, the construction waste will be separated at the site or comingled on-site and then separated at an off-site facility.
So you are sure the construction waste is being properly discarded, the contractor should provide a written statement with each payment application certifying what percentage of debris was discarded in an environmentally friendly manner. At project sign off, the contractor should submit a final waste removal and recycling report that includes an itemized chart listing the exact volume/weight of each type of construction debris picked up from the job site and the percentage that was successfully recycled. The price that the "green" waste removal firm receives for the recycled materials typically offsets the extra costs involved in sorting the debris, so the firm's fee is usually no more than what it would charge for carting away construction waste and dumping it in a landfill.
LEED Points
Buildings that use sustainable materials and follow environmentally sound practices receive points toward LEED (Leadership in Energy and Environmental Design) certification. But even if your cooperative is not pursuing or eligible for such certification, it is still responsible and can be cost-effective to incorporate a green approach to repair and upgrade work.
Keep in mind that many contractors are resistant to changing the way they've always done things, so they may not embrace your board's enthusiasm for making your repair and upgrade project green friendly. Moreover, the particulars of each property make some sustainable practices harder to implement than others. So as the field continues to evolve, it will require education and due diligence on the part of owners, managers, and their engineers and architects to sort out what is right for each individual building. But by keeping green alternatives in mind and selecting them when possible, your cooperative—as well as the environment at large—will benefit.
Stephen Varone, AIA is president and Peter Varsalona, PE is principal of RAND Engineering & Architecture, DPC. This column was originally published in the April 2010 issue of Habitat Magazine.
