Improving Indoor Air Quality With the Right Construction Materials

Topics: indoor air quality, LEED, construction materials, indoor environmental quality

Flori Muresan
Author : Flori Muresan on July 3, 2020

Indoor air quality projects often focus on existing buildings, which are already occupied. To help prevent COVID-19 in particular, ASHRAE recommends more outdoor air ventilation, upgrading to higher-efficiency air filters, and adding ultraviolet germicidal irradiation. However, air quality starts from the design stage, and the selection of construction materials is very important.

In most cases, materials in new buildings are also new, but this means they have high chemical content left from their manufacturing process. Many of these substances evaporate at room temperature, and for this reason they are called volatile organic compounds (VOC). There are thousands of these substances, and many have negative health effects. For example, many wood products have a high content of formaldehyde, which causes respiratory irritation.


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VOC Off-Gassing in New Constructions

molecules

When a building has been recently completed, indoor spaces often smell “like new”. However, this is not a good thing, since the smell is actually caused by new materials releasing VOCs. Unlike other air pollutants with unpleasant smells, many VOCs are odorless, and some even have pleasant smells.

New materials have a higher VOC concentration, compared with materials that have been installed for years. VOCs are released at a faster rate due to their high concentration, through a process called off-gassing. A high VOC concentration in a new building can irritate the respiratory system, and asthma patients are susceptible to flare-ups. Long term exposure to VOCs has been linked with more severe conditions like organ damage and cancer.

Increased ventilation can reduce VOC levels: they are diluted when fresh outdoor air is mixed with indoor air, and they are removed by exhaust fans. However, air filtering is not effective, since VOC molecules are too small even for HEPA filters. Ultraviolet germicidal irradiation is not effective either, since VOC are nonliving substances.

LEED Requirements for Low-Emitting Materials

modernoffice-1

Considering the negative air quality effect of VOCs, the LEED certification offers 1-3 points for low-emitting materials. The US Green Building Council divides materials into seven categories, each with its own requirements:

  • Interior paints and coatings applied on site.
  • Interior adhesives and sealants applied on site, including flooring adhesive.
  • Flooring
  • Composite wood
  • Ceiling, wall, thermal and acoustic insulation
  • Furniture
  • Exterior applied products, in the case of healthcare facilities and schools

For LEED certification purposes, the building interior includes everything within the waterproofing membrane. On the other hand, the building exterior is everything outside the membrane, which includes the waterproofing system itself.

The LEED credit for low-emitting materials considers both the chemical content of materials and an assessment of indoor air. Any tests and measurements involved must be conducted by a laboratory with the ISO/IEC 17025 accreditation.

The points earned depend on the number of compliant categories among the materials used, and the following table summarizes the requirements for each building type.

Schools and Healthcare Buildings

Without Furniture

 

With Furniture

 

Categories Used

LEED Points

Categories Used

LEED Points

3

1

4

1

5

2

6

2

6

3

7

3

Other Buildings

Without Furniture

 

With Furniture

 

Categories Used

LEED Points

Categories Used

LEED Points

2

1

3

1

4

2

5

2

5

3

6

3

There may be cases where some compliant products are not available. When this happens, LEED allows the budget calculation method, which considers flooring, ceilings, walls, thermal and acoustic insulation, and furniture. In the case of schools and healthcare, exterior applied products are also considered. A detailed calculation procedure is provided by the USGBC, and points are awarded based on the total percentage of compliant materials:

  • At least 50% compliant materials - 1 point
  • At least 70% compliant materials - 2 points
  • At least 90% compliant materials - 3 points

Low-emitting products make building interiors healthier,  especially when combined with effective ventilation. Air filtering and UV disinfection can be used to deal with larger particles and air pollutants of biological origin.

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