Plastic duct covers not all they’re wrapped up to be
Leadership in Energy and Environmental Design is a ratings system for the design, construction, operation and maintenance of buildings, including homes and whole neighborhoods.
Created by the U.S. Green Building Council, LEED’s performance credit system aims to allocate points based on the potential environmental impacts and human benefits of each credit. The more credits a building obtains, the higher the level of LEED certification can receive. According to the USGBC’s website, www.usgbc.com/leed, “LEED-certified buildings save money and resources and have a positive impact on the health of occupants, while promoting renewable, clean energy.”
From the location of the building to the cleaning products used in the final facility, all are considered when it comes to certification.
One credit that LEED offers pertains to HVAC construction indoor air quality management. This green HVAC credit is achieved in part by ensuring that the ends of ductwork are covered with plastic during transportation and while on the construction site. The rule states: “The contractor should protect all HVAC equipment from both dust and odors and seal all ducts and equipment openings with plastic.”
However, there does not seem to be definitive evidence that covering the ductwork leads to an increased level of indoor air quality.
The ductwork remains wrapped in plastic for only a fraction of the total construction time. Where it is fabricated, its ends are wrapped as it is prepared for shipment. When the ductwork arrives at the jobsite, it is still covered, but as soon as the ductwork is ready to be installed, the plastic wrap is removed and discarded. Throughout processes like drywall installation and sanding, the interiors of the ductwork are compromised. On most construction sites, the HVAC system is turned on to maintain proper conditions for drywall mud to cure. Through this common practice, the ductwork system’s interior, which had been carefully kept in its immaculate state, becomes exposed to the very dust and debris that is said to be removed from the equation through the use of plastic wrap.
In addition, ductwork used in LEED projects is often lined with fiberglass insulation. When air runs through lined ducts, it most likely picks up traces of fiberglass from frayed edges where the liner has been cut. This raises the question of whether or not new ductwork is appropriate for maintaining indoor air quality. Wrapping the ends of lined ductwork may prevent dust from entering the duct during transportation, but it simultaneously keeps stray fiberglass inside.
Perhaps the HVAC market should eliminate the use of plastic ductwork fabrication wrap. After the system is installed, it could be run with test filters, trapping any dust that made its way into the ducts. Just before project completion, the filters would be replaced with new ones, and proper indoor air quality would be achieved without ever using the wrap. This would allow any loose fiberglass insulation to be collected and removed from the HVAC construction system before the building is ready.
May not be recycled
Many plastic duct wrap manufacturers advertise that their product is fully recyclable, yet there is no way to ensure that it ends up that way. Ripped off the ductwork on the jobsite, plastic wrap is oftentimes stuffed into a trash bin. Due to the lightweight nature of the product, the wrap often blows away and ends up in trees or on the street like plastic grocery bags.
On top of these points, the total cost of using wrapped ductwork for a project is greater than one would think.
Energy is required to manufacture the plastic wrap. Created by applying an acrylic adhesive to low-density polyethylene film, the plastic wrap is rolled around a cardboard tube.
And when the wrap is on the ductwork, it poses an even larger problem — one likely overlooked by the creators of the credit. When loading ductwork onto a truck, fittings are normally nested inside one another, allowing more ductwork to be loaded onto each truck. However, when the fittings’ ends are wrapped in plastic, this option is eliminated. Because of this limitation, more truckloads are required to complete a delivery. Jobs that could be delivered in one round trip now take two or three. This forces the supplier to use more gasoline, further polluting the environment, adds to vehicle wear and tear, and creates inefficient use of labor.
It becomes obvious that the costs of using plastic wrap likely outweigh the benefits.