Why some green buildings may be hazardous to health: new report

 In Climate Change, the Indoor Environment, and Health, a forthcomingreport from the Committee on the Effect of Climate Change on Indoor Air Quality and Public Health and Institute of Medicine, some health hazards that have come about from what may have been too hasty adoption of what were intended to be helpful standards have been delineated, as follows:

Air sealing.

Steps taken to make buildings more airtight may lower ventilation rates and, in the absence of source control or the introduction of mechanical ventilation, increase both indoor-air contaminant concentrations and indoor-air humidity. Sealing also has the potential to modify internal air pressure and thus create other problems, such as deficiencies in the makeup air for combustion appliances and exhaust fans. Changing the pressure dynamics in a house can cause depressurization of the foundation or slab and lead to intrusion of soil gases and radon.

Increased insulation.

Heavily insulated foundation, wall, and roof systems are more vulnerable to water intrusion, air leakage, and water-vapor migration than more traditional assemblies. Adding insulation to foundations, walls, and roof systems that currently have subacute rain seepage or condensation problems can lead to decay, mold growth, or corrosion problems. Adding insulation to the bottom side of some roof decks or to the inside of brick walls in cold and mixed climates may result in moisture problems.
Some insulation materials may contain irritating chemical compounds, such as formaldehyde in UFFI and some fiberglass insulation and hexabromocyclododecanes (HBCD) in polystyrene insulation (Harrad et al., 2010; Roosens et al. 2009). The long-term durability of spray-on polyurethane foams is of concern because their thermal degradation can generate and release hydrogen cyanide, carbon monoxide, amines, and isocyanates (Carter, 2010).
Building codes in high-risk termite areas often prohibit the use of foam-board insulation on the exterior of a foundation because it interferes with the application of soil pesticide treatments. Foam board on either the interior or exterior of a foundation also makes it difficult to inspect for signs of termite invasion, such as mud tubes (Ogg, 2006). If changes in climatic conditions lead to termites’ becoming endemic in areas of the country where they were not previously a problem, structures that have this form of insulation could be more susceptible to infestation.

High-efficiency combustion equipment.

Replacing atmospherically vented combustion equipment (such as furnaces, boilers, and water heaters) in single-family and low-rise multifamily residential buildings with at least 90% efficient combustion or electric equipment lowers the ventilation rate in basements and crawlspaces. In some buildings, that may change the indoor moisture balance and result in cold-weather condensation in the building enclosure. The lowered ventilation rate may also result in increased radon exposure.

Appearance of “legacy hazards.”

Older homes may have materials that, if disturbed during renovations for energy improvements, can cause health hazards for renovation personnel and occupants. Those materials include asbestos in insulation and tiles and polychlorinated biphenyls (PCBs) in caulking. PCB-containing caulking materials—commonly used in the late 1950s though the 1970s—also pose a liability for owners of buildings constructed during that period, including schools and other public structures.

The full report will be available later this year.