The Indoor Environment
Poor indoor environmental quality (IEQ) can have adverse effects on occupants’ health and productivity. When designing a building, strategies such as ventilation effectiveness and contaminant control, or the requirement of a building flush-out prior to occupancy, can improve the resulting IEQ. These steps can help reduce potential liability, increase building market value, and help maintain higher productivity. Techniques for building a healthier indoor environment include ample daylighting and access to fresh air, along with the specification of automatic sensors and controls, while plastics can also have significant impact in this area.
Spray polyurethane foam
Environmental control within a building envelope depends on strong interaction between heat, air, and moisture transport collectively. Three spray polyurethane foam (SPF) systems are used within the building envelope:
- High density (24 and 32 kg/m3 [1.5 to 2 pcf]).
- Low density (less than 8 Kg/m3 [0.5 pcf]).
- Sealant foams.
High-density SPF is used when strength, high moisture resistance, and high insulating value is desired, while low-density SPF is used when some insulation, air barrier, and sound control is desired.1 (Sealant foams are used to caulk around windows, doors, sill plates, and other locations to seal against unwanted air infiltration.
The possibility of better climate control afforded by the use of SPF systems can not only save energy and make the building more comfortable, but also can help reduce building deterioration. SPF’s climate-control ability can enable downsizing of the HVAC equipment of a building, further reducing energy use. Side-by-side energy efficiency comparisons have shown that spray polyurethane foam provides energy savings of up to 40-percent over other insulation materials.2
During the production of expanded polystyrene insulation, neither chlorofluorcarbons (CFCs) nor hydrochlorofluorocarbons (HCFCs) are used. Therefore, the installed insulation does not experience off-gassing that may effect indoor air quality (IAQ). The American Lung Association (ALA) Health House® guidelines, among the toughest in the nation for indoor air quality, uses expanded polystyrene (EPS) sheathing as an example to insulate foundation walls and floors due to its “slow rate of water vapor movement by diffusion and air transport through the insulation”.3 Other ALA-registered homes have incorporated insulating concrete forms (ICFs) to meet stringent requirements. It is important to note ALA representatives do not endorse specific materials or products, but the group says expanded polystyrene walls release no lung-damaging fibers.4
ICFs and structural insulated panels (SIPs) offer tight construction that effectively controls air infiltration of pollutants, enabling more efficient control of indoor air quality.
Insulation made from extruded polystyrene (XPS) can be an important part of a construction IAQ management plan, which is often part of green-building rating programs. The material is designed to reduce the moisture infiltration and condensation. Additionally, extruded polystyrene generates neither dust nor airborne contaminates during construction.
XPS insulation contains no volatile organic compounds (VOCs) as defined by the U.S. Environmental Protection Agency (EPA), thereby addressing concerns about indoor chemical pollutant source control. In general terms, XPS insulation also helps maintain comfortable temperatures, which, as previously mentioned, can foster an indoor environment conducive to productivity. More specifically, extruded polystyrene insulation in insulated concrete panels provides heightened thermal insulation value, while XPS insulation used in opaque wall areas (a trade-off for more glazing area) assists with Leadership in Energy and Environmental Design® (LEED®) credits dealing with daylighting and views.
Vinyl products in flooring, wallcovering, and upholstery are among the easy-to-clean surfaces that can help minimize the opportunity for buildup and proliferation of common indoor pollutants in homes, commercial projects, and healthcare facilities. For example, researchers at Chicago, Illinois’ Northwestern Memorial Hospital found upholstery such as vinyl (which can be easily disinfected) provides less opportunity for the proliferation of antibiotic-resistant microbes than fabrics. Surveys of interior designers who specialize in healthcare design found many professionals prefer sheet vinyl flooring where infection control is an issue, since its seams can be heat-welded and it is self-coving.
Where it is important to minimize the amount of volatile organic compounds inside a building, properly installed vinyl products have no recognized adverse impact on indoor air quality—the small amount of VOCs emitted dissipate quickly through normal ventilation. Nevertheless, manufacturers of vinyl wallcovering and flooring are aggressively pursuing performance improvement, developing innovations including mildew-resistant or micro-vented products that allow moisture trapped behind a show surface to escape.
The Resilient Floor Covering Institute (RFCI), in conjunction with Scientific Certification Systems (SCS), launched its FloorScore program the summer 2005. The certification program tests flooring products for compliance with the strict IAQ emission requirements adopted in California.
1 For more on these types of SPF, see “Learning the Difference Between ½-lb and 2-lb Spray Polyurethane Foam,” by Mason Knowles in the November 2004 issue of Modern Materials.
2 “Energy Conservation and Thermal Envelope Design Using Polyurethanes, Spray Polyurethane Foam.” Savings vary. Find out why in the seller’s fact sheet on R-values. Higher R-values mean greater insulation.
3 For more information, visit www.healthhouse.org.
4 Visit http://www.arxx.net/.