Maryland Energy Code Requirements

The 2019 Maryland Building Performance Standards reflect a number of key state building envelope changes that are part of the 2019 Maryland state code for energy conservation. In March of 2019, Maryland adopted the 2018 IECC with changes to the air exchange rate. Local jurisdictions have until March 25, 2020, to make local amendments and enforce the code. 

The most important building envelope changes in Maryland state code affected prescriptive window requirements, the required air exchange rate, duct leakage requirements, and the use of county-specific requirements related to the Energy Rating Index (ERI) compliance path. Maryland building code insulation requirements remain the same as specified by the previous code.

Overview of Maryland’s 2019 State Building Envelope Code Requirements:

  • Prescriptive home insulation requirements in Maryland remain the same as the previous code, relative to the building envelope.
  • The prescriptive window requirement changed to a U-factor of 0.32 in climate zone 4 and 0.30 in climate zone 5 (Garrett County only).
  • The required air exchange rate can now be traded off up to a maximum level of 5 ACH50 in either the performance or ERI paths.
  • Ducts are required to have a total leakage rate less than or equal to 5 CFM25/100 SF of duct and a leakage rate to the outside of less than or equal to 4 CMF25/100 SF of duct. R401 through R404 still need to be met when using the ERI compliance path.
  • Homes built in Maryland must have an ERI of less than or equal to 62 unless located in Garrett County, they are required to have an ERI of less than or equal to 61.

What is the Energy Rating Index? 

The ERI provides an alternative path for energy code compliance. Builders using this path need to achieve a certain score, on a scale from 0 to 100, to achieve energy efficiency code compliance for building construction. The score of 100 aligns with the 2006 IECC model code. A lower score means a more energy efficient home.

In Maryland, the target ERI score is 62 in Climate Zone 4 and 61 in Climate Zone 5, and RESNET-accredited software is used to calculate the ERI score.

While the ERI is a performance path approach, it also carries certain mandatory elements. For example, if a builder uses the ERI path, the insulation levels must still meet or exceed the prescriptive levels found in the 2009 International Energy Conservation Code.

There are two distinctions for builders using the Energy Rating Index (ERI) path:

  • The ERI path is distinct from the Home Energy Rating System (HERS index scale) since other approved home rating programs could, in theory, be used for ERI compliance.
  • Both HERS and ERI allow for the use of renewable energy to reduce scores, however, ERI includes provisions to ensure that renewable energy does not replace more permanent or reliable energy efficiency measures. As a matter of practice, the ERI path calls for builders to use HERS to demonstrate building code compliance, and the energy conservation code contains minimum provisions for the building envelope.

To view a summary of the key residential energy code requirements reflected in the 2019 Maryland Building Performance Standards, download the detailed summary.

This summary is offered for informational purposes only. It does not purport to be an exhaustive analysis of code changes or provide advice that will ensure guaranteed compliance with any energy code provision. Please consult with local authorities before finalizing your installation plans.

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