Comparing IEQ in Rating Systems for Sustainable Design

Green building rating systems not only offer frameworks, or sets of metrics, from which to evaluate levels of sustainability that buildings can attain, they also set priorities and/or weight certain areas of design.

Frameworks for sustainable design exist for new construction, existing buildings, commercial, residential and special purpose buildings. In each case, a system of categories, such as energy efficiency, water efficiency, materials, indoor environmental quality, sustainable sites, and so forth makes the process easier to understand and manage.

There are numerous green building rating systems to choose from that will help builders think through the process from an initial eco-charrette to the final Certificate of Occupancy.

Over a series of articles, I’ll compare the most well-known rating systems and consider how they treat these major sustainability categories. The three major rating systems we’ll focus on are:

• LEED® v4 Building Design and Construction (BD+C)
• Green Globes™ New Construction (NC)
• Living Building Challenge

In the last article, I compared then green building rating systems in the Water Efficiency category. In this article, we’ll examine the Indoor Environmental Quality category.

LEED v4 Building Design + Construction (BD+C)

LEED® is a voluntary rating system that uses a points-based system to determine various, increasingly higher, levels of certification.

LEED® has several prerequisites that must be met, as well as a minimum of points that must be earned to reach the “Certified” level. Additional points may be earned to achieve increasingly greater levels of certification. “Certified” (40-49 points), “Silver” (50-59 points), “Gold” (60-79 points), or “Platinum” (80-110 points).

LEED v4 was recently released as the newest version of LEED after LEED 2009. In the LEED v4 Indoor Environmental Quality (EQ) Category there are 16 total potential points available. Therefore, just to meet the “Certified” level, the EQ category alone could supply 40% (16/40) of the total points required, in addition to meeting the required prerequisites. If the highest level of certification was attained (Platinum), the EQ category could supply just 20% (16/80) of the total points required.

Here is a list along with a brief description of the credits within the LEED® v4 BD+C EQ category:

Green Globes™ New Construction (NC)

Green Globes™ is also a voluntary rating system, however unlike LEED® there are no prerequisites required. There are a few eligibility requirements, however.

Eligible buildings must score a minimum of 35% of the total applicable points through a preliminary self evaluation, they must attain a minimum percentage of points in each environmental assessment area, have no more than 18 months of occupancy at the time the assessment is ordered, and be at least 400 gross square feet in size.

There are 1000 total points available in the Green Globes™ rating system, with 160 points available in the Indoor Environment category, which is similar to the EQ category for LEED® V4. Like LEED®, there are four levels of certification. Buildings that achieve at least 350 of the 1000 points are eligible for certification, earning a rating of “One Globe.” Buildings that achieve at least 550 points will earn “Two Globes,” while buildings achieving at least 700 points will earn “Three Globes.” Lastly, a building that achieves at least 850 points will earn the highest level of “Four Globes.”

Therefore, in the Green Globes™ system, achieving all of the points in the Indoor Environment category would account for 45.7% (160/350) of the points required to earn “One Globe,” and would account for 18.8 % (160/850) of the required points to earn the highest level of certification.

Here is a list along with a brief description of the credits within the Green Globes™ New Construction Indoor Environment category:

Living Building Challenge

The Living Building Challenge has several “petals”, or categories, similar to LEED® and Green Globes™. However, in this rating system, a building can be certified three different ways: Either Full certification, “Petal” recognition, or Net Zero Energy Building Certification.

There are seven “Petals”: Site, Water, Energy, Health, Materials, Equity, and Beauty. Within these seven petals, there are twenty “imperatives” which must be met, similar to a LEED® credit. However, in order to reach Full Certification in the Living Building Challenge, all twenty imperatives must be met.

In order to attain Petal recognition, the project must satisfy the requirements of three or more petals, and at least one of the following must be included: Energy, Water, or Materials. The Health Petal is most similar to the LEED® EQ category and the Green Globes™ Indoor Environment category. The intent of the Health petal is to focus on the major conditions that must be present to create robust, healthy spaces, rather than to address all of the potential ways than an interior environment could be compromised.

The Health petal includes the following three imperatives: