NGBS and Energy Performance: Voluntary Green Standard Compared to Building Codes

With so many green rating systems available, understanding how each one compares to others is imperative for making a choice that works best for your project, climate zone and market. The recent release of the 2020 National Green Building Standard™ (NGBS) provides a great opportunity to conduct a side-by-side comparison, starting with energy performance — an easy element to measure. Buyers also can relate to energy performance without difficulty; they desire energy efficiency, whether it's the numbers they see on their electric bill or the familiar ENERGY STAR label.

In exploring different certification levels under the NGBS, one approach is to compare how homes built to each level match up with different versions of the International Energy Conservation Code® (IECC®) adopted around the country. Take single-family homes and low-rise multifamily buildings, for instance:

• A home built to the 2020 NGBS at the Bronze level will be approximately 26% more energy efficient than a home built to the 2009 IECC.
• A home certified to the 2020 NGBS Silver level would be around 7.5% more energy efficient than one built to the 2018 IECC.
• When comparing a project that achieves the highest level of certification under the 2020 NGBS (Emerald) to one that meets the requirements of the 2012 IECC, there's a 22.5% increase in energy efficiency.

These differences highlight the importance that third-party certifications bring in terms of verifying energy performance claims. By exploring Home Innovation Research Labs' latest comparisons, you can get a better sense of how rigorous energy efficiency standards in the 2015 NGBS and the 2020 NGBS measure up to several residential building codes and other above-code programs. The latest version of NGBS also offers greater flexibility by allowing builders and designers to choose the best compliance path for their projects.

Understanding the nuances between the requirements of each code and green rating program can further strengthen the case for certifying your projects to the NGBS to distinguish them in the marketplace. Having these comparisons in your toolbelt can also assist in building consensus for incentivizing voluntary green programs such as the NGBS.

For more information about NAHB's sustainable and green building programs, contact Program Manager Anna Stern. To stay current on the high-performance residential building sector with tips on water efficiency, energy efficiency, indoor air quality, and other building science strategies, follow NAHB's Sustainability and Green Building team on Twitter.