Sustainable uses for plastic pipe
Statistics prove green building construction is not a fad, that it is here to stay.
Statistics prove green building construction is not a fad, that it is here to stay. In a June 2014 McGraw Hill Construction report on green multifamily and single-family homes, almost two-thirds (62%) of single-family home builders say more than 15% of their projects are green. By 2018, that percentage increases to 84%.
During the Great Recession and subsequent periods of high energy prices, many homeowners and building owners looked to the heating and cooling industry for energy-efficient solutions to lower utility costs. Manufacturers continue to fine-tune technology to get the most efficiency from their products.
Along those same lines, water conservation has been a critical issue in the Western states for the past few years, culminating in California’s mandatory water reduction rule, the most stringent water efficiency standards in the country.
The primary goal of sustainable building systems is to conserve energy and water. In 2011, the Plastic Pipe and Fittings Association and the Plastic Piping Education Foundation commissioned a report on the sustainable uses of plastic pipe.
Water conservation technologies include graywater reuse systems (also called reclaimed or recycled water systems) and rainwater catchment systems. Graywater systems take wastewater from bathroom sinks, tubs/showers and washing machines, and reuse such water for toilet/urinal flushing or irrigation. Purple-colored PVC, CPVC and PEX is available to help identify nonpotable water lines, while piping used to collect and convey graywater to the holding tank is typically ABS, PP or PVC drain, waste and vent.
“Plastic pipe is considered suitable for graywater reuse applications because it does not corrode with acidic or aggressive water,” the report notes.
Rainwater catchment or harvesting systems collect rainwater from a commercial or residential building’s roof or property. Use of harvested rainwater generally includes irrigation, flushing toilets and washing laundry, the report says; however, in certain parts of the country (e.g., California and Texas), “rural households rely on rainwater as the only source of water for all household activities.”
Rainwater harvesting not only reduces potable water consumption, but is an effective strategy for managing storm water runoff rates, the report states. Purple-colored plastic pipe also is used in rainwater catchment systems.
On the energy conservation side, geothermal systems using ground-source heat pumps is a growing heating and cooling technology in the United States. They use the renewable source of natural heat and heat storage capacity of the earth or groundwater to provide energy-efficient space heating/cooling or domestic water heating.
Geothermal energy systems consist of the indoor heat pump equipment, a ground piping loop and a flow center to connect the heat pump and the loop. The ground loop, which is invisible after installation (it is buried or submerged), allows for the exchange of heat energy between the earth or groundwater and the heat pump.
“[High-density polyethylene] pipe is commonly used for geothermal energy systems loops, given its flexibility, resistance to chemical attack and corrosion, low cost and long service life,” the report explains. “PE also is chosen because of its ease of joining using fusion welds, allowing for long runs underground without fittings.”
High-efficiency hot water distribution systems that use plastic pipe such as CPVC or PEX have been shown to waste less energy and water than alternative metal piping systems, as stated by the “Evaluation of Residential Hot Water Distribution Systems by Numeric Simulation” study conducted by the Buildings Technology Center at the Oak Ridge National Laboratory. This is due to the insulating properties of plastic and the thicker walls of PEX and CPVC.
Lastly, radiant heating systems use piping or tubing to efficiently distribute heated water throughout a building, either under floors or in ceilings and walls. The typical material used for radiant floor piping is PEX.
“Its flexibility makes installation easier, especially in smaller diameters,” the PPFA report says. “Some manufacturers offer composite PEX-AL-PEX and PE-AL-PE pipe and fittings for the distribution piping. Composite pipe is often used when the installation has to be done by one person since the pipe can be shaped without it recoiling back to its original shape.”