Five major changes in IECC 2021 designers need to be aware of
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Overview
IECC 2021 is slowly but surely being adopted through the United States. This article highlights five (5) of the most significant changes so individuals and companies involved in commercial construction can be better prepared with how the new regulations in the code will affect their projects.
While not as critical to safety as other building codes, energy codes affect a project’s cost, aesthetics, and the operations and maintenance of the building once occupied and it’s important for building professionals to stay abreast of changes.
By being aware of the changes, building professionals can proactively update building owners, plan for the impacts in their projects, and avoid the difficult and expensive changes to plans later in the process.
Energy Code Overview
Before covering the big changes, here are a few big picture insights into IECC and energy codes in general:
1) IECC is based on ASHRAE 90.1
The latest version of IECC is dated two years after the latest version of ASHRAE 90.1. This is because ASHRAE 90.1 is a major part of basis of IECC: some sections are even identical verbatim.
In fact, as seen in the image below, compliance with IECC can be achieved with ASHRAE 90.1 as a complete alternative (C401.2.2).
2) There are multiple methods of compliance
Many projects use IECC and COMchecks (aka the ‘Prescriptive’ path) because “that’s the way it’s always done”. In actuality, there are multiple ways, to achieve compliance. In most cases, there are actually FOUR or more different methods! Visually, this can be seen below.
Here is a quick overview of these terms:
Mandatory
These are non-negotiable, required components of a project. They must be met to achieve compliance.
There will be slight differences between ASHRAE 90.1 and IECC.
Prescriptive
This typically means using COMchecks, though not always.
This is a ‘checklist’ approach to building energy efficiency with limited opportunity for tradeoffs. In some cases, the requirements to ‘check off’ may not result in much energy saving value relative to the cost.
With IECC, there is an ‘additional efficiency package’ where one energy efficiency category needs to be exemplary. This is not the case with ASHRAE 90.1.
Performance
This means using an energy model to demonstrate that total building energy cost/use is less than a baseline, allowing tradeoffs between disciplines. This is covered in Section C407 in IECC and Chapter 11 (and Appendix G in 90.1-2016 and later) in ASHRAE 90.1.
This method typically costs more than prescriptive but can increase design flexibility and reduce construction cost by eliminating costly prescriptive requirements.
Five Big Changes
The following sections outline five (5) of the most significant changes to IECC 2021, primarily from a cost standpoint. Excerpts from the code are included for reference in each section.
1) Fault Detection Systems
Buildings (except R-1 and R-2 occupancies) over 100,000 ft2 are required to have an HVAC fault detection and diagnostic (FDD) system installed. Previous versions of IECC had similar language, but it was only for air-side economizers.
The new requirements expanded the FDD language but imposed a minimum square footage, sparing smaller buildings that previously needed FDD systems for their economizers. Now, buildings over 100,000 ft2 will need an FDD system, likely as part of a building automation system (BAS) to alert building operators of HVAC equipment failures.
2) Residential Energy Recovery
The growing requirements for energy recovery in HVAC units with high fractions of outdoor air (OA) is expanded by now requiring energy recovery on nontransient dwelling units (aka dorms, apartments, and condos, but not hotels). These spaces are continually occupied with continuous fresh air requirements, so code developers are wanting to recover the exhausted air’s energy to reduce heating and cooling costs. Small units under 500 ft2 and buildings on the Pacific coast are excluded from this requirement.
This requirement has the potential to be quite expensive in extra mechanical system components and/or architectural features to add and hide the necessary duct work and energy recovery devices.
However, unlike other energy recovery requirements, this requirement is not a mandatory requirement and can be excluded by using the performance path of compliance in section C407. Many multifamily developers are opting to use this option.
3) Automatic Receptacle Control
Automatic receptacle control requirements have been a part of ASHRAE 90.1 since the 2010 version and have led designers and building owners to actively avoid the ASHRAE 90.1 energy code unless absolutely necessary. This is due to both the added cost as well as the concerns of the building users losing power to their equipment.
IECC has finally added and required this section, so, barring specific municipality exceptions, building designers and users alike will need to get used to having 50% of 120V receptacles in offices, conference rooms, copy/print rooms, break rooms, classrooms, and workstations automatically controlled by an occupancy sensor or a scheduling system.
4. Energy Monitoring
Energy monitoring is a new category in IECC where metering systems, besides the utility meter, are now required on most buildings over 25,000 ft2. This system will record and store the electrical energy data from the different building energy end uses, such as HVAC, interior/exterior lighting, plug loads, and significant process loads.
This will give building operators clearer indications on where and when increasing energy use might be coming from rather than a normal electric bill that includes just gross monthly consumption. This is a mandatory requirement in both ASHRAE 90.1 and IECC, so designers and building owners will need to include this in new building designs. This new requirement is closely related to a LEED credit, so buildings pursuing LEED certification will have an extra point baked in.
5. Additional Efficiency Packages
Unique to IECC since 2012 (it’s not in ASHRAE 90.1), is the Additional Efficiency Package section of C406. This has been the final step of prescriptive compliance where one category, often interior lighting, needs to be exemplary.
Now renamed as Additional Efficiency Requirements, IECC 2021 has expanded C406 to give variable points based on building type and climate by way of tables (example listed below). Now, buildings will need to accumulate 10 “credits”, with only certain categories, building and climate categories able to fully provide this. In many cases, two or more strategies may need to be used.
Other Changes
This article is focused on five major changes in the IECC 2021. There are a lot of other changes as well. Most of which are typical of energy code updates: energy efficiency levels and categories increased.
Increasing efficiency requirements include U-Values and SHGC levels in the building envelope section, lighting power requirements in the electrical section, and HVAC efficiencies in the mechanical section. Additionally, more categories, such as mechanical and refrigeration equipment and plant growth lighting have been added.
Note that some of these changes, particularly insulation increases in cold climates, have the potential to substantially increase project costs.
In Summary
IECC and ASHRAE 90.1 are closely related and there are multiple paths within each that can be used for code compliance. The optimal choice will vary by project.
Fault Detection Systems, Automatic Receptacle Control, and Energy Monitoring are now required additions to many buildings. Project teams should plan accordingly.
Residential Energy Recovery is now required on most non-transient dwelling units, though this can be avoided using a performance path of compliance.
The Additional Efficiency Package section (C406) has evolved where different strategies have varying weights depending on the building type and location. Now, multiple, exemplary strategies are needed to get the ten (10) credits. An example would be reduced interior lighting power and 5% cooling efficiency improvement.
What about your project?
Contact us if you need any help with energy code compliance for a project in the US, regardless of location or code.
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About Craig Green
Craig Green is the managing principal at G2 Energy Solutions, an energy engineering consulting firm based in Phoenix, Arizona. Over the last decade, Craig has performed the created energy models for performance code compliance on dozens of buildings across the country. Craig has also advised on and created COMchecks on many others.
For questions on the article or to discuss working with G2 Energy Solutions, please contact Craig at 480-637-7900 or craig.green@g2energysolutions.com.
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