However, in some projects, ERVs may not be included due to cost, space constraints, or design decisions. For projects without ERVs, it becomes especially important to use other strategies to maintain balanced airflow and indoor air quality across the building. 

Why Airflow Balance Matters in Multifamily Buildings 

Multifamily buildings rely on coordinated ventilation across many individual units stacked vertically and horizontally. When airflow is not properly balanced, it can lead to: 

• Uneven indoor air quality between units 

• Pressure differences between apartments and corridors 

• Increased energy use from HVAC systems working harder than necessary 

• Comfort issues such as drafts or stuffiness 

• Moisture and condensation issues in envelope components 

As buildings increase in height and number of floors, these challenges become more pronounced. Stack effect, the natural movement of air upward through a building, and pressure variations make it harder to maintain consistent performance from the bottom floor to the top.  This can be exacerbated by negative pressures accumulating from floor to floor and creating issues with opening and closing doors, especially in lower floors. 

Alternative Ventilation Strategies  

If a project is not using ERVs, one or more of the alternative ventilation strategies below can be used to properly balance airflow.  

1. Over Supply to the Corridors via DOAS 

One of the most common alternatives is the use of Dedicated Outside Air Units (DOAS).  In most cases these units are used effectively as a “common ERV”. Installed on the roof, DOAS collect exhaust air from apartment bathrooms throughout the building and supply conditioned outdoor air to the corridors. The corridors have an oversupply of outside air, which causes them to be positively pressurized, while the apartments are negatively pressured.  The intent is for air to transfer from the positively pressurized corridor into the negatively pressurized apartments through undercut doors and other transfer pathways. 

2. Exhaust Ventilation with Trickle Vents 

Another common method of balancing ventilation without the use of ERVs is to have a constant exhaust flow, such as from a bathroom or kitchen, and trickle vents.   

Trickle vents are openings in the exterior envelope that allow outdoor air to enter the building. The intent is for the incoming air from the trickle vents to offset the exhaust air being removed, helping to maintain ventilation balance. 

3. Packaged Terminal Air Conditioner with Louver 

Another option for balancing pressures within a multifamily building is to use Packaged Terminal Air Conditioners (PTAC) with built-in outside air louvers.  This approach is similar to a trickle vent in that it allows outdoor air to enter the space and offset exhaust airflow. However, when the PTAC is operating, the incoming air is conditioned before entering the apartment. When the PTAC is not running, such as during periods of continuous exhaust ventilation, unconditioned outdoor air can still enter the space due to the negative pressure created by the exhaust system. 

Balanced Ventilation Without ERVs – Key Points 

While ERVs remain a preferred solution for many multifamily projects, alternative strategies can still achieve effective ventilation when thoughtfully designed and coordinated early in the process.  The most successful multifamily projects are those where ventilation is not treated as a standalone system, but rather as an integrated part of the building’s overall energy and airflow strategy. 

When ERVs are not part of the design, successful ventilation strategies typically rely on a combination of systems, rather than a single solution. 

A well-balanced approach may include: 

• Over Supply to the Corridor via DOAS 

• Exhaust Ventilation with Trickle Vents 

• Package Terminal AC with Louver 

Each strategy plays a different role, but together they help maintain balanced airflow across the building. 

ReVireo helps project teams evaluate ventilation strategies through energy modeling, understand code implications, and develop practical solutions tailored to each multifamily project. Whether ERVs are included in the project plans or alternative approaches are needed, our team can help ensure systems are balanced, compliant, and aligned with long-term performance goals. Contact us to discuss your upcoming projects.   

The post Alternative Ventilation Strategies to ERVs in Multifamily Buildings  appeared first on ReVireo.

To mitigate the impact of these new requirements, multifamily project teams are increasingly choosing to comply with energy code via alternative performance pathways.  These pathways use energy modeling to increase design flexibility and avoid costly new prescriptive requirements for projects four stories or greater in height, including energy recovery ventilators (ERVs) in dwelling units.

Two Sets of Pathways for 2021 & 2024 IECC Compliance

The 2021 & 2024 IECC offer two sets of pathways for buildings defined by IECC as commercial, including multifamily buildings four stories or greater in height.  Each set of pathways approaches energy efficiency requirements differently, offering advantages and disadvantages.

1.     Prescriptive Pathways

IECC Sections C402 through C406 and ASHRAE 90.1 Sections 5.5, 6.5, and 7.5

These pathways are the most straightforward and prescribe a set list of requirements for each building component, including lighting, heating and cooling systems, and the building envelope. If everything meets the minimum standards, the project complies.  Most owners and designers are familiar with COMCheck, the software most used to show compliance via these pathways.

While these pathways are simple to follow, they do not allow much flexibility. Each requirement must be met as written, which can lead to design limitations or added system requirements. Limited trade-offs within the building envelope are permitted, but trade-offs between building components are not allowed.

Under 2021 & 2024 IECC, ERVs are required to be included in the dwelling units for multifamily projects defined as commercial, which is an important change from prior version of the IECC.

2.     Performance Pathways

IECC Section C407 and ASHRAE 90.1 Appendix G and Chapter 11

These pathways use sophisticated energy modeling software to compare a proposed building’s design to a baseline building defined by the code. If a building performs as well as or better than the baseline, it complies. These pathways allow trade-offs between building components. This flexibility creates meaningful opportunities to optimize design decisions, balance costs, and align systems with project priorities rather than following a rigid prescriptive approach.

For example, improvements in lighting efficiency may offset HVAC energy usage, or high-performing mechanical systems may create flexibility in other areas of the design, such as window specifications or continuous exterior insulation. Because of this flexibility, performance pathways are a better fit for more complex or cost-sensitive projects.

Additionally, the prescriptive requirement for ERVs in dwelling units can often be avoided, unlocking significant cost savings for multifamily projects.

2021 & 2024 IECC Commercial Compliance Pathways – Click to Enlarge

How the Performance Pathways Avoid Prescriptive ERV Requirements

Under the 2021 and 2024 IECC, there is a new prescriptive requirement that dwelling units are required to have ERVs. ERVs are designed to capture energy from exhaust air and use it to condition incoming outdoor air. They are an effective best practice, but also add cost, take up space, and require ongoing maintenance.

One of the advantages of the performance pathways is the ability to avoid prescriptive requirements, including ERVs in dwelling units. Improvements in lighting efficiency, better insulation, or high-performance glazing can offset the energy impact of not having ERVs in dwelling units. If the energy model of the building meets or exceeds the efficiency of the code baseline building, the ERVs are not necessary to comply.

By avoiding ERVs, multifamily building projects can:

• Lower initial equipment costs, unlocking significant cost savings for projects; and
• Simplify mechanical system design, making systems easier to maintain and less costly to operate.

The decision whether to utilize ERVs in dwelling units should not be solely based on construction cost comparisons.  Factors like climate zone, building type, and ventilation requirements must all be carefully considered. Building developers who plan to own and operate the building for the foreseeable future may choose to include ERVs to capture long-term energy savings.

If ERVs are not utilized in dwelling units, there are additional methods to consider for balancing airflow within the building, such as adding supplemental supply or exhaust ventilation, transfer grilles, jump ducts, or dedicated make-up air strategies. In general, as buildings increase in height and number of floors, balancing airflow throughout the building becomes more challenging. Energy modeling creates the opportunity to evaluate all different ventilation and airflow balancing approaches as part of a whole-building strategy, allowing the project team to optimize performance rather than follow a one-size-fits-all prescriptive solution.

Additional Benefits of Energy Modeling

Energy modeling is at the core of the alternative performance pathways, and it is becoming more popular for good reason. Producing an energy model yields several additional benefits.

1. Smarter Design Decisions

Energy modeling evaluates how the whole building performs instead of treating each component requirement as a fixed rule. This allows design teams to make more informed decisions early in the process.  Instead of overdesigning every component, teams can prioritize strategies that deliver the greatest impact, whether that is improving the building envelope, optimizing lighting, or right-sizing heating and cooling systems.

2. Maximize ROI

By identifying the most effective energy efficiency measures, energy modeling helps teams avoid unnecessary upgrades that add cost without meaningful return. It creates a clearer path to balancing performance, budget, and compliance while reducing upfront costs and still meeting energy code requirements.

3. Confidence in Real World Performance

Energy modeling provides detailed insight into how a building is expected to perform once it is built.  This goes beyond compliance and helps teams anticipate energy use, improve occupant comfort, and support long term operational savings

Setting Your Project Up for Success

If you are considering a performance pathway for your project, timing of energy modeling is key. Bringing in an energy modeler early in the design process allows for better coordination and more opportunities to optimize the building. Waiting too long can limit your options and reduce the potential benefits.

It is also important for the full project team to stay aligned. Architects, engineers, and owners all play a role in shaping building performance. Small design decisions can have a large impact on energy outcomes, so collaboration is essential.

Key Takeaways

The 2021 and 2024 IECC provide multiple pathways for compliance for buildings defined as commercial, but the right choice depends on your project goals.

The prescriptive pathways are the most familiar option with straightforward requirements, but they can be restrictive and require costly equipment investment like ERVs in dwelling units for multifamily projects. The performance pathways use energy modeling, provide design flexibility, valuable performance insights, and potential cost savings in both the short and long term.

For many teams, the performance pathways and energy modeling turn compliance into an opportunity rather than a constraint. Reduce costs, minimize risk, and find the smartest pathway to compliance with ReVireo. Contact us to get started.

The post Unlocking Alternative Energy Code Performance Pathways for Multifamily Buildings with Commercial Energy Modeling appeared first on ReVireo.

The update was officially approved on October 16, 2025, and became effective January 1, 2026. Any design or construction contract executed on or after January 1, 2026, or any permit application submitted on or after July 1, 2026, must comply with the updated UCC. 

The adoption of the 2021 IECC series introduces significant updates across multiple areas of construction. For both residential and commercial projects, the changes impact structural design, mechanical systems, electrical work, and energy efficiency requirements. 

The 2021 IECC brings a range of changes for both commercial and residential projects. Here are some of the most important to be aware of for energy code compliance.  

PA 2021 Residential Energy Code Key Updates 

• 2018 Insulation Table Retained – Pennsylvania did not adopt the updated 2021 IECC insulation table. As a result, projects will continue to use the 2018 insulation requirements for code compliance.

• No Additional Efficiency Package Requirement – The state did not adopt the 2021 IECC’s “additional efficiency” package options, preserving greater flexibility for builders. 

• Alternative Pathways Offer More Flexible Envelope Leakage Targets – Under certain alternative compliance pathways, the allowable building envelope leakage is less stringent than under the standard prescriptive pathway, providing additional design flexibility. 

PA 2021 Commercial Energy Code Key Updates 

Pennsylvania adopted the 2021 IECC commercial provisions with targeted modifications, including: 

• ERVs are Required – Under the prescriptive path (i.e. COMcheck) energy recovery ventilators are required for all dwelling units. Energy modeling offers more flexibility and enables avoiding ERV (Energy Recovery Ventilator) installation. 

• Commissioning Requirements are Expanded – Commissioning requirements are more defined and stringent, making it more enforceable. 

• All Code Pathways Have Increased Energy Efficiency– Under the prescriptive path, specifically building envelope and lighting components have become more efficient. 

What the PA Energy Code Update Means for the Industry 

Pennsylvania’s version of the 2021 IECC: 

• Strengthens core efficiency standards 

• Maintains strong inspection and documentation requirements 

• Preserves flexibility in certain design areas 

• Avoids some of the more aggressive national add-ons 

For builders, developers, and design professionals, energy modeling, duct performance, and documentation remain central to compliance under the updated code. 

If you have questions about how these updates impact your upcoming projects, our team is here to help. Contact us for guidance on navigating the new requirements in Pennsylvania and ensuring your projects remain fully compliant. 

The post 2026 Pennsylvania Energy Code Update: 2021 IECC Effective July 1 appeared first on ReVireo.

EPA Administrator Zeldin testified on Tuesday at a hearing and confirmed the media reporting about his intention to relocate the ENERGY STAR program, possibly to the private sector, and incorrectly claimed that the ENERGY STAR program is not required by law to be run by federal agencies.  ENERGY STAR was originally created in the 1990s, but the Energy Policy Act of 2005 mandated that the ENERGY STAR program be operated by the EPA (with support from DOE).  Federal legislation would be required to change that.

There are a lot of potential outcomes here.  It’s possible EPA could simply try to push the limits of what the law requires by defunding and/or deprioritizing while continuing to operate it.  It’s also possible that EPA could try to transfer more responsibilities to DOE.

Ultimately, we suggest a wait-and-see approach here.  ENERGY STAR is a highly complex, multifaceted program with thousands of stakeholders, that has existed for over 30 years.  Accordingly, it will not be easy to simply unwind it or transfer to the private sector, and currently federal law does not allow that anyway.

There will assuredly be more news about this in the coming weeks and months.   For those interested in learning more now about the future of the ENERGY STAR program, we suggest this article from Green Building Advisor and this podcast from Building Efficiency Resources, on which our CEO, Matthew Kaplan, was a guest among other industry leaders.

More urgently, on Wednesday night, the House of Representatives passed the Republican reconciliation bill. The bill includes a full repeal of the 45L Tax Credit for homes acquired after the end of 2025, or the end of 2026 for homes that were already under construction as of May 12, 2025. 

For background, the 45L Tax Credit (45L) was created in the Energy Policy Act of 2005 and signed into law by President George W. Bush. From 2006 to 2022, qualification for 45L was based on energy savings vs. energy code (IECC).  The Inflation Reduction Act of 2022 extended the credit through 2032, increased the amount of the credit, and changed the qualification requirements to be based on ENERGY STAR (with a higher amount for additionally earning Zero Energy Ready Home certification).

The reconciliation bill now goes to the Senate.  We suggest that everyone reach out to their Senators directly, and through trade organizations like NAHB, to explain that homebuilders and developers across the country have invested significant time and money to build homes that are eligible for the tax credit, and this near-immediate repeal would completely pull the rug out from under businesses and housing projects that have been planned for multiple years out.  This includes many low-income and affordable housing projects.  The path to energy independence and housing affordability for our nation is not to make it more expensive to build homes and to have them use more energy.

In addition to lobbying to prevent the outright immediate repeal, we suggest that you consider contingency planning in case the repeal becomes law.  If you are developing ENERGY STAR homes that either:

• a) Did not start construction before May 12^th and will not be acquired for use as a residence by the end of 2025; or
• b) Started construction before May 12^th but will not be acquired for use as a residence by the end of 2026.

then you should consider if the business viability of pursuing ENERGY STAR for these homes depends on 45L.  There are many intrinsic benefits of ENERGY STAR, including ensuring the quality installation of insulation, air barrier, and HVAC systems that improve quality assurance and risk management while reducing operating costs.  However, many of these benefits can also be obtained by the Home Energy Rating System (HERS) process itself, even if the HERS process isn’t being used to verify ENERGY STAR, or through building commissioning.  If pursuing ENERGY STAR does not make sense for your business without 45L, then you should consider not pursuing ENERGY STAR for any homes that meet either of the above criteria.

While these rapidly unfolding events are occurring simultaneously, it’s important to keep in mind that the ENERGY STAR program and the 45L Tax Credit are two different things.  The more immediate and serious concern to homebuilders and developers is the repeal of 45L, which the residential construction industry has benefited from for the past two decades.

For anyone in the residential construction industry, or anyone whose business has otherwise benefitted from 45L in the past two decades, the most important thing you can do right now is to call your U.S. Senator’s office and tell them your personal story about how 45L has helped your business as well as housing affordability.  Explain how disruptive it is to abruptly end a tax credit that has been in effect since 2006 and is currently extended through 2032, which businesses have spent years planning and incurring costs to utilize. Explain to U.S. Senators the timing and planning involved in the design and construction of residential housing, especially multifamily housing, and the pivotal role that 45L plays in making homes more affordable to build and operate.

CLICK HERE TO CALL YOUR U.S. SENATORS AND TELL THEM TO SAVE 45L.

The post The Uncertain Futures of the ENERGY STAR Program and the 45L Tax Credit appeared first on ReVireo.

Each year, the ENERGY STAR program honors a select group of businesses and organizations that have made outstanding contributions to energy efficiency and the transition to a clean energy economy. ENERGY STAR award winners lead their industries in the production, sale, and adoption of energy-efficient products, homes, buildings, services, and strategies. These efforts have saved more than 5 trillion kilowatt-hours of electricity over the past 30 years.

“President Biden’s Investing in America agenda creates unprecedented opportunity to build a clean energy economy, and private sector partners through programs like ENERGY STAR are leading the way,” said EPA Administrator Michael S. Regan. “I congratulate this year’s ENERGY STAR award winners for their innovation and leadership, in delivering cost-effective energy efficient solutions that create jobs, address climate change, and contribute to a healthier environment for all.”

Winners are selected from a network of thousands of ENERGY STAR partners. For a complete list of 2024 winners and more information about ENERGY STAR’s awards program, visit energystar.gov/awardwinners.

Watch the video below to learn more about the meaning of ENERGY STAR partnership.

About Us

ReVireo is an energy efficiency and green building services company that provides analysis, consulting, and verification services to help clients determine and achieve target levels of energy efficiency and sustainability for building projects throughout the Northeast and Mid-Atlantic.

ReVireo’s mission is to enable clients to generate a return on investment in buildings’ energy efficiency and sustainability. The company is supported by a talented, attentive and reliable team of building experts including: LEED Accredited Professionals & Green Raters, RESNET HERS & EPA ENERGY STAR Raters, DOE ZERH Verifiers, PHIUS+ Raters & Verifiers, NGBS Green Verifiers, IECC/HERS Compliance Specialists, Certified Energy Managers (CEM), Existing Building Commissioning Professionals (EBCP), Building Energy Modeling Professionals (BEMP), Certified Building Commissioning Professionals (CBCP) and Licensed Professional Engineers.

ReVireo’s services help clients reduce the cost, difficulty, and risk involved with compliance with building energy codes and energy efficiency and green building certification programs.

About ENERGY STAR

ENERGY STAR^® is the government-backed symbol for energy efficiency, providing simple, credible, and unbiased information that consumers and businesses rely on to make well-informed decisions. Since 1992, ENERGY STAR and its partners helped American families and businesses avoid more than $500 billion in energy costs and achieve more than 4 billion metric tons of greenhouse gas reductions. More background information about ENERGY STAR’s impacts can be found at www.energystar.gov/impacts.

The post ReVireo Earns 2024 Energy Star Partner of the Year Award appeared first on ReVireo.

Significant Changes from 2018 to 2021 IECC 

The IECC defines residential buildings as single family and multifamily buildings three stories or less. There are three significant changes for residential buildings.  

• Reference Insulation Requirements 
• Additional Energy Efficiency Requirement 
• Required Duct Leakage Testing 

Reference Insulation Requirements 

Reference insulation requirements will significantly increase, including the addition of continuous exterior insulation. Thus, alternative pathways like the Performance Pathway or the ERI Pathway that allow for additional tradeoffs may be more financially beneficial. 

Additional Energy Efficiency Requirement 

Projects will now require an additional energy efficiency option, no matter the energy code pathway. The IECC provides multiple options, including, but not limited to: 

• 5% improved UA Tradeoff, Performance, or ERI calculation 

• Improved HVAC or plumbing efficiency 
• All ductwork in the conditioned space 
• Airtight envelope with Energy Recovery Ventilation 

Duct Leakage Testing 

Duct leakage testing will be required for all HVAC systems, including those in the conditioned space. 

How ReVireo Can Help 

ReVireo offers energy code compliance services to guide your team and projects through the compliance process and the code change. To learn more about the services we offer, visit our Services page. Connect with our experts today to discuss your next project’s 2021 IECC compliance strategy.  

The post Connecticut Adopts 2021 IECC: Overview of Changes for Residential Projects appeared first on ReVireo.

With a constantly evolving workforce, ReVireo offers a flexible work environment. Before the COVID-19 pandemic, ReVireo encouraged employees to develop a hybrid schedule if desired. Remote and on-premise work allows employees to balance work and individual circumstances. Providing understanding and flexibility when personal situations arise, ReVireo supports employees’ changing needs. As a company dedicated to preserving the natural environment, ReVireo also acknowledges the benefit of remote work regarding reduced carbon emissions from limited transportation. ReVireo offers a myriad of benefits beyond remote work flexibility to create a competitive and compelling compensation and benefits package. ReVireo offers health insurance, parental leave, and 401k accounts with partial match, as well as paid time off and paid volunteer time. 

Dedicated to professional and personal development, ReVireo offers to fund further education. Should an employee find a seminar or event that would bolster their knowledge and benefit their position within the company, ReVireo will cover travel expenses and associated costs. Furthermore, ReVireo will contribute to the tuition costs if an employee pursues higher education relevant to their role. ReVireo strives to foster a learning environment through internships for students or continued education for employees. 

ReVireo is also dedicated to supporting local communities and philanthropic organizations through food drives, volunteer service, and donations. ReVireo employees participated in Sleep Out with Covenant House and raised over $20,000 for homeless youth. ReVireo employees also volunteered to build homes for Habitat for Humanity. ReVireo strives to donate to causes that resonate with their employees, including the American Cancer Society and the Cancer Research Institute. ReVireo strives always to support its clients’ philanthropic endeavors and will continue to provide services and donations to partner on these important initiatives.

ReVireo strives to create a positive environment for employees to grow professionally and personally. If you are interested in joining the team, email a resume and cover letter to [email protected]. To see currently open positions, check out our Careers page.

The post Benefits of Working for ReVireo appeared first on ReVireo.

Accessibility 

ReVireo offers its clients access to its key staff and top management. Each project is a high priority for our team, regardless of size. With a team full of experts, ReVireo can collaborate and strategize with design professionals, construction managers, finance and investment experts, and everyone in between.  

Stewardship 

ReVireo effectively manages resources and time to ensure the best use of clients’ time and money. ReVireo provides clients with the information and support for successful projects, often taking a leadership role.  

Passion 

Our team cares deeply about the environment and, by extension, about energy efficiency and green building. We enjoy sharing our enthusiasm with clients and staying ahead of regulatory updates and developments in the industry, ensuring our clients are the first to know of significant changes.  

Humility 

ReVireo looks to build life-long partnerships with clients by understanding them. ReVireo values collaboration, always providing the best advice while listening and responding to the client’s needs and concerns.  

Teamwork 

ReVireo utilizes cross-functional collaboration to ensure our team finds the best way to bring a project to fruition and meet or exceed determined objectives.

The post ReVireo’s Values appeared first on ReVireo.

Local Law 97 (LL97) is part of New York City’s ambitious plans to address greenhouse gas emissions and work toward a carbon-neutral city by 2050. Covered buildings include those over 25,000 gross square feet, two or more buildings on the same tax lot that exceed 50,000 gross square feet, or two or more buildings owned by a condo association governed by the same board of managers and exceeds 50,000 gross square feet. Covered buildings that exceed emission limits will be charged an annual fee of $268 per ton of CO2 over the limit. With most buildings’ deadlines in 2024, annual fines will begin in 2025.   

The proposed rules include a formula for determining buildings’ annual greenhouse gas emissions limits, calculating the buildings’ energy use, and benchmarking utilizing ENERGY STAR Portfolio Manager. On November 14, the proposed rules will be open to public comment through written comments and a virtual public hearing. The adopted rules will likely be published late in 2022.  

The LL97 Covered Buildings List includes the buildings that must comply starting in 2024, with a report due by May 1, 2025. The compliance requirements will become more stringent as the years progress, mandating a 40% reduction in emissions by 2030 and 80% by 2050 across New York City. It is advisable to plan ahead and meet requirements now, especially in the case of new construction. This removes the pressure of future deadlines and the need for later costly updates. 

An annual emissions report must be certified by a Registered Design Professional, which includes Registered Architects and Professional Engineers. Benchmarking is required for other Local Laws and can be utilized for LL97 to determine if an existing building will comply. If it does not comply, the building will need an energy audit and subsequent retrofits to ensure compliance with LL97. Benchmarking cannot be utilized for new construction. Instead, an energy model can be created early to inform design decisions.  

The NYC Accelerator program offers guidance to private property owners working toward compliance. NYC Accelerator provides compliance recommendations, low-interest financing, and incentive program guidance. ReVireo is a participant in the NYC Accelerator Service Provider Program. ReVireo performs analysis, consulting, and verification services that can support projects to decarbonize NYC, cut energy-related costs, and build a healthier city.  

The post NYC’s Local Law 97 Proposed Rules appeared first on ReVireo.

What is an Envelope Leakage Test? 

An envelope leakage test is performed by an energy professional to quantify the air tightness of the building. Envelope leakage can lead to poor indoor air quality and difficulty controlling indoor temperatures, significantly impacting residents’ energy usage and comfort. The envelope leakage test is colloquially referred to as a “blower door test” because the diagnostic tool used to perform the test is called a blower door. A blower door is a calibrated fan installed in an exterior doorway. The fan creates a pressure difference between the inside and outside of the building. Taking the air out of the home allows the remaining air to escape through other avenues, allowing the tester to identify where cracks, insulation gaps, or other envelope errors exist. The amount of air leakage from the building envelope can then be quantified using a highly accurate gauge that measures the depressurization and the amount of airflow through the fan. The measurement is used to identify leaks in the envelope.   

2018 IECC vs. 2021 IECC – What You Need to Know 

The IECC defines residential buildings as single family and multifamily buildings that are three stories or less. Under the 2018 IECC, an envelope leakage test is required post-construction in addition to a visual air barrier inspection pre-sheetrock. However, New Jersey amended the 2018 IECC to include an amendment that allowed builders to demonstrate the air leakage rate by either a post-construction envelope leakage test or a visual air barrier inspection pre-sheetrock. Historically, many builders opted for the visual inspection since it was an easier path to compliance. As a result, many builders have not yet implemented sufficient air-sealing strategies to comply with the mandatory envelope leakage test requirement in the 2021 IECC.  

Builders will need to collaborate with design professionals to detail air sealing scopes of work in plans and with construction trades to execute properly to pass the blower door test under the new code.   

The envelope leakage limit in the 2021 IECC is 3 ACH for detached single-family attached homes and 0.3 CFM per square foot of enclosure area for any type of attached homes, as tested with a blower door. Passing the envelope leakage test will require careful planning and preparation. See below for tips to increase your chances of compliance. 

Tips for Passing the Envelope Leakage Test 

• Start your learning curve early when you still have a margin for error. Aim to achieve 2021 IECC envelope leakage limits on homes permitted under the NJ-amended version of the 2018 IECC. This will help you understand what additional work will be required to comply with the 2021 IECC standards when they become mandatory.  Don’t wait until it counts to start your learning curve.  
• Have a trained energy professional such as a HERS Rater or Rating Field Inspector inspect air sealing details before installing drywall on every home or sampling of homes. Coordinate with construction trades to attend this inspection for training. 
• Ensure your design team considers the new envelope leakage testing requirements when creating plans and specifying products. Designing more robust exterior air barriers with more air sealing details included will help your envelope leakage test results. Ensure all contracts with relevant trades include notes for envelope leakage testing. 
• For more complex buildings, a 3rd party envelope plan review by an energy professional can be useful to address any potential leakage points and ensure that the plans reflect all details necessary to pass the envelope leakage test.  
• Poorly sealed top plates can lead to air leakage. Ensure the top plate is sealed properly. To learn more, see our video. Although it mentions the 2015 IECC, it applies to all versions of the IECC. 

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