How Healthy is your Precast?

By Claude Goguen, P.E., LEED AP

As the green building movement continues its steadfast march, developers and specifiers want to know more about the construction materials they choose. We’ve written about Environmental Product Declarations, a new tool that enables specifiers to quantify the environmental impacts of different materials in order to make an informed decision on what to use. EPDs provide an environmental footprint but do not factor in health.

Perhaps you’ve heard of sick building syndrome. The term describes situations in which building occupants experience health and comfort effects that appear to be linked to their physical surroundings. Lack of fresh air is one of the major causes and is especially common in newer, energy-efficient buildings where windows have been sealed shut. Another cause of SBS is poor air quality from emissions of volatile organic compounds by sources such as carpeting, adhesives, paints, manufactured wood products and other building products. Since most people spend 75-to-90% of their time indoors, the interior air quality can have a significant impact on their health. This puts a spotlight on indoor environmental quality.

According to a McGraw Hill report titled “The Drive Toward Healthier Buildings,” the health and comfort of building occupants is expected to have a higher impact on building design and construction decisions in the next two years.

A few years ago, a group of green building industry leaders came together to develop a tool to fill the need for health information, thus the Health Product Declaration was created. An HPD is a report of the materials or ingredient contents of a building product and its associated health effects. The HPD provides an inventory of contents and associated health hazards, but stops short of assessing risk with the actual use of the product.

The HPD Version 1.0 was introduced at Greenbuild 2012, and the non-profit Health Product Declaration Collaborative was launched as a customer-led membership organization to develop the HPD.¹ LEED v4 includes the HPD as an acceptable documentation pathway for the new Materials and Resources credit: Building product disclosure and optimization-materials ingredients. So how does it work? It’s actually easier compared to other sustainability-related documentation.

After going to the Health Product Declaration Collaborative website and creating an account, you are asked to add the intentional contents of the structure. For example, if I start to type in cement, it will autofill the entry with Portland cement. Then you fill in additional information detailing the percentage of final weight, recycled content and role of this material. Based on this and other data inputs, the tool creates an HPD that can be handed to specifiers as required.

Precast = indoor air quality

Precast concrete contains little-to-negligible levels of VOCs. That level can be controlled by careful selection of low-emitting form releases, curing compounds, damp proofing materials and sealants. Table 1 contains VOC concentrations and emission rates for concrete and other common materials.

Precast concrete wall panels that are 3 inches or more thick act as an air barrier and limit moisture intrusion thus contributing to indoor air quality. Due to its thermal mass, concrete also aids in controlling indoor temperature fluctuations which is a large factor in occupant comfort.

The good news is precast concrete buildings inherently help provide a healthy environment for occupants, yet manufacturers must be prepared to provide documentation to support this claim. The amount of requests for HPDs is growing. In fact, an NPCA member was asked for an HPD earlier this year. Don’t be caught off guard. Be ready when that request comes across your desk.

Claude Goguen, P.E., LEED AP, is NPCA’s director of Sustainability and
Technical Education.

Resources:

Health Product Declaration Collaborative, www.hpdcollaborative.org

EPA “Indoor Air Facts No.4, Sick Building Syndrome,” 1991, www.epa.gov/iaq/pdfs/sick_building_factsheet.pdf

PCA Concrete Thinking – Indoor Air Quality – www.concretethinker.com/solutions/Indoor-Air-Quality.aspx 

McGraw Hill Construction – The Drive Toward Healthier Buildings, 2014

¹ www.hpdcollaborative.org