By 2020, discussions of indoor environmental quality, energy, building science and techniques, and material composition and sourcing will be one in the same. The driver: an increased focus on the health of a building’s occupants.
The residential green building market in the United States is booming as the housing market recovers, and recent research shows that improving the quality of construction and the residents’ quality of life have emerged as the most important reasons for building green.
However, while buildings often highlight energy and environmental conservation in their selection of green features such as airtight construction, energy-efficient products, and water-efficient plumbing, these attributes may inadvertently contribute to poor indoor air quality (IAQ). Currently, health experts estimate that poor IAQ places more than 40 percent of the U.S. population at risk for serious health problems such as asthma and respiratory disease, cancer, cardiovascular disease, and may cause neurodevelopment and reproductive problems.
Supertight homes with minimal ventilation and low outdoor air change rates can result in elevated levels of indoor air pollutants that threaten occupant health. Conversely, to pursue good IAQ without considering the efficient use of energy may unnecessarily increase construction and energy costs, financial hardships for families, and emissions of greenhouse gases, thereby contributing to outdoor air pollution and an increased carbon footprint. All those involved in building and renovating homes must strive towards adopting one common, defining set of green principles that give equal emphasis on energy efficiency and protecting occupant health.
To reach a place where this is common, by 2020, we must address the following issues:
Energy conservation efforts. High energy costs are accelerating pressures to decrease ventilation rates in buildings, and common techniques that are being used to do so—such as tightening the building envelope, sealing gaps in the air distribution systems, and managing indoor-outdoor air pressure differences—are resulting in tighter buildings and decreased air change rates. In a recent study by the state of California of 108 new homes, more than 50 percent of them had less than 0.3 air changes per hour, the level currently recommended by ASHRAE for residential buildings. In addition, the state of California’s chronic reference level for human exposure to formaldehyde was exceeded in 98 percent of the homes. We must learn how to build tight while still providing adequate ventilation.
Climate change. Extreme environmental conditions and occupant behavior will have a significant impact on IAQ, as people are likely to spend even more time inside, extending their exposure time to potential indoor pollution. The most sensitive populations, children and the elderly, will seek refuge indoors and create a greater need for clean indoor air. However, the introduction of new materials and weatherization techniques may lead to unhealthy pollutant exposures. Materials used in construction and furnishings will require resiliency to extreme temperatures and moisture, and this will lead to new formulations of products and new chemicals.
Extreme weather events may cause damage to building envelopes and allow for severe water intrusion, leading to a haven for biological contamination and allergens. Well-designed HVAC systems will be a must, and cleaning outdoor air will become more important as changing environmental conditions may even lead to a more-polluted supply.
Chemical usage. Many synthetic chemicals are primary components of construction materials, furnishings, and consumer products. It is estimated that less than 5 percent of industrial chemicals have been evaluated for toxicity and bioaccumulation and, in many cases, there is insufficient health data to understand their effects on human health before they are used. Studies indicate that some chemicals may be harmful to humans at doses that were considered negligible in the past. Combining this concern with the fact that indoor air is a complex mixture of hundreds of VOCs, SVOCs, and chemical-laden dust particles mandates a clear call for solutions.
So where do we go as 2020 approaches?
Experts agree that controlling the use of pollutants at the source is the only truly effective way to remove them from indoor environments, and combining this with good ventilation strategies is the key to improving IAQ. Experts also agree that the total eradication of indoor air contaminants often is neither feasible nor practical, especially in homes. A more realistic goal is to use building materials, furnishings, finishes, office equipment, and cleaning products and processes that emit lower and more-benign levels of VOCs, SVOCs, and other pollutants. Enabling the process of making products more sustainable are new tools that provide rapid toxicology assessment, international schemes that aid chemical management and harmonization of safety assessments, alternative product assessment programs that incorporate toxicity, technology, and economic feasibility, and verified safer chemical lists that will enable this entire process.
Ventilation and air cleaning are invaluable to the health of a building’s occupants, and the two work hand-in-hand, as many types of air cleaners are an integral part of the HVAC system. A well-designed and properly operating HVAC system brings in and conditions outdoor air and circulates it through the building. This not only warms and cools the air and manages humidity, but it also dilutes indoor air pollutants to minimize their impact on the indoor environment and the building’s occupants.
A new emphasis should be on integrated building design and operation where IAQ and human health are required elements. High-performance building guides will need to step up beyond minimum codes to address a range of human sensitivities, incorporate material emissions data, and obtain ongoing performance data of the buildings. Tools that will be key to the success of this will include third-party labeling programs for the identification and verification of low-emission and resilient construction materials and furnishings, building assessments that verify energy use and acceptable IAQ during operation, and real-time monitoring tools that provide feedback loops for continuous optimization for energy use and IAQ.
The bottom line is this: Going forward, energy conservation and IAQ must be considered together and have equal priority in the design, construction, furnishing, and operation of a home or building. One without the other can lead to significant occupant health or comfort issues or increased energy costs and carbon footprints. By 2020, we will need to recognize this and better respond to both human and planetary health.
Chemicals of Concern
Xylenes Most Frequently Found VOCs in Green Commercial Construction*
* From a 2012 UL study of 12 green-certified buildings