Chinedu Moneke, PE

Putting the EE in GREEN: Energy Efficiency Compliance for Single-Family NGBS Green Certification

NGBS Green Certified homes perform better than code minimum homes in many ways, but energy efficiency is one of the most tangible benefits to homebuyers. Benefits of an energy-efficient home include lower utility bills, increased comfort, and improved resale value. When it comes to energy efficiency, there are two options for demonstrating compliance to the National Green Building Standard ICC-700 (NGBS) – the Prescriptive Path or the Performance Path.

Builders interested in pursuing NGBS Green certification often ask which energy compliance option they should pursue. Below, we explain the two compliance options to help you decide which one is best for your next project.

NGBS Prescriptive Path Option

The Prescriptive Path is like a recipe. It provides the designer with a series of mandatory “ingredients” – building component thresholds that must be met or exceeded to demonstrate compliance. Common prescriptive measures include minimum R-values for insulation or wall assemblies; acceptable infiltration rates; and efficiency requirements for mechanical systems, such as water heaters and HVAC equipment. The architect or builder designs the home to meet the Prescriptive requirements, and then an accredited NGBS Green Verifier must inspect the home to confirm compliance by verifying that the energy efficiency items on the list are successfully included in the home.

The Prescriptive option can be used by builders seeking Bronze, Silver, or Gold certification levels through NGBS Green, but is best suited for homes pursuing Bronze or Silver because it the path to achieve those levels is more straightforward. Builders who are new to green, high-performance construction techniques might also find the Prescriptive option an easier starting point. If the home is pursuing ENERGY STAR certification or a HERS rating, the Performance option described below should be used instead. The NGBS Prescriptive options include the following pathways:

 

The 703 Prescriptive Path is the most affordable option because it does not require additional REScheck documentation, which can incur additional time and cost.

When to use:

• Builders new to green building certification.
• Homes pursuing NGBS Bronze or Silver level certification.
• High-volume builders with many models/options who are looking for a production-friendly certification process.
• Homes in the Tropical Climate Zone.

NGBS Performance Path Option

The Performance Path has fewer mandatory practices than the Prescriptive option. The Performance option allows builders to make efficiency tradeoffs between components rather than having a fixed list of required components. Instead of a checklist of mandatory practices or systems, this option sets an efficiency baseline above the minimum building code and allows the builder to be more creative from a design perspective as to how the home meets the minimum efficiency requirements. Builders demonstrate a home’s compliance by using energy modelling software to show that the annual energy performance is at least equal to or better than that of a building built using the Prescriptive IECC or IRC code. The Performance option is the only way a home can earn NGBS Green’s Emerald certification level.

When to use:

• Homes pursuing the Gold and Emerald certification levels may prefer the Performance Path option because the energy model is a useful tool for the builder and Verifier to evaluate various combinations of design strategies, components, and technologies until they arrive at a design solution that provides the greatest energy savings for the least cost.
• Homes also pursuing ENERGY STAR certification or a HERS rating, regardless of the NGBS certification level desired, should use this because an energy report is required for these programs and can be used to satisfy the NGBS’s energy requirements, thereby saving time and additional cost.
• Homes that encounter limitations in meeting the Prescriptive option threshold(s) and need to use efficiency tradeoffs between components to demonstrate compliance.
• Homes using renewable energy because the NGBS allows builders to include the savings from renewable energy in the efficiency analysis.

The NGBS Performance options include the following pathways:

 

The “Alternative Bronze/Silver” path should only be used when also pursuing ENERGY STAR, because additional reports and confirmed ratings might be needed, which can incur extra costs. Only the energy modelling report is needed for the 702-Performance Path.

The NGBS Green program provides builders with multiple energy paths for achieving energy compliance for their home’s certification. Both paths help builders design and construct more efficient homes that cost less to operate and are more comfortable to live in.

Still have questions on the best path for you? Talk to your NGBS Green Verifier or contact us.

** The NGBS 2020 Chapter 12 Certified Path energy compliance will be covered in more detail in a future blog. Stay tuned!

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