Understanding the Commercial HVAC Energy Code Landscape
Energy efficiency codes for commercial HVAC systems operate within a two-code framework that facility managers must understand before planning any new installation, major replacement, or renovation project. The two foundational documents are ANSI/ASHRAE/IES Standard 90.1, published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, and the International Energy Conservation Code (IECC), published by the International Code Council (ICC).
These are not competing codes -- they are complementary. ASHRAE 90.1 is the technical backbone that drives commercial energy efficiency requirements nationwide. The IECC commercial provisions reference ASHRAE 90.1 extensively and, in many jurisdictions, the two are adopted together or one is adopted as a reference standard within the other.
The U.S. Department of Energy's Building Energy Codes Program (BECP) determines whether new editions of ASHRAE 90.1 and the IECC represent an improvement over the previous edition and supports states in adopting updated codes. Under the Energy Conservation and Production Act (ECPA), once DOE issues an affirmative determination for a new edition of 90.1, each state has two years to certify that it has reviewed and updated its commercial building code to meet or exceed that edition. DOE issued its determination for 90.1-2022 on March 6, 2024, which set a state certification deadline of March 6, 2026.
For facility managers, compliance is mandatory for new construction, major renovations, and equipment replacements in most U.S. jurisdictions. Understanding what the codes require -- and how to verify compliance -- is essential to avoiding enforcement actions, failed inspections, and unnecessary energy costs.
The Relationship Between ASHRAE 90.1 and the IECC
ASHRAE 90.1 and the IECC share the same goal but approach it through different organizational frameworks. Facility managers encounter both codes depending on the jurisdiction and project type.
ASHRAE 90.1 is a technical standard updated on a three-year cycle. Current editions in widespread adoption include 90.1-2019 and 90.1-2022. The 2022 edition added an optional HVAC Total System Performance Ratio (TSPR) compliance method, a condensing-level efficiency requirement for larger gas hot-water boiler systems, and a new mandatory Section 11 "energy credits" requirement. ASHRAE estimates the 2022 edition reduces energy costs by over 15 percent compared to the 2019 version and by more than 48 percent compared to the 2004 version. DOE's own analysis for its determination estimated national savings of about 9.8 percent site energy and 8.9 percent energy cost versus 90.1-2019.
The IECC is a model building code also updated on a three-year cycle. Its commercial provisions (Chapter 4 [CE]) contain their own prescriptive requirements and also allow ASHRAE 90.1 to be used as an alternative compliance path. HVAC equipment efficiency tables in each IECC edition generally track a recent edition of 90.1, but the two documents are not identical, so confirm requirements against the specific edition your jurisdiction adopted.
State adoption varies. Many states adopt the IECC (which permits 90.1 as an alternative) or adopt 90.1 directly, often with state amendments. California writes its own energy code (Title 24, Part 6). Before beginning any project, verify the current adopted code in your jurisdiction through your state energy office or local Authority Having Jurisdiction (AHJ).
Know Your Jurisdiction
The edition of ASHRAE 90.1 or IECC adopted in your state may be one or two cycles behind the current published edition. Always confirm the adopted version with your local building department before specifying equipment efficiency ratings.
Minimum Equipment Efficiency Requirements
How Efficiency Is Measured for Commercial HVAC
Commercial HVAC equipment uses several performance metrics, and understanding the differences is critical for compliance:
- SEER2 (Seasonal Energy Efficiency Ratio 2): A revised metric that took effect January 1, 2023 for central air conditioners and heat pumps regulated as consumer products (single-phase units under 65,000 BTU/h), replacing the older SEER rating. SEER2 uses an updated test procedure with higher external static pressure that better reflects field installation conditions.
- EER2 (Energy Efficiency Ratio 2): The revised steady-state efficiency metric under the same updated test procedure. Federal EER2 minimums apply to certain air conditioners sold in the Southwest region.
- IEER (Integrated Energy Efficiency Ratio): The federally regulated metric for air-cooled commercial unitary equipment -- primarily rooftop units (RTUs) -- from 65,000 up to 760,000 BTU/h. IEER weights performance at several part-load conditions (100%, 75%, 50%, and 25% load), making it a better real-world measure than full-load EER alone. DOE has adopted a new IVEC metric for this equipment with a January 1, 2029 compliance date.
- COP (Coefficient of Performance): Used for chiller efficiency, heat pumps in heating mode, and certain large refrigeration equipment.
- kW/ton: Used for chillers. Lower values indicate higher efficiency.
DOE Minimum Efficiency Standards Effective January 1, 2023
DOE's energy conservation standards for central air conditioners and heat pumps (10 CFR 430.32(c)) moved to the SEER2/EER2/HSPF2 metrics for products manufactured on or after January 1, 2023. Split-system air conditioner minimums are higher in the Southeast and Southwest regions, and the Southwest adds EER2 minimums; heat pump minimums are national. The Southwest region is Arizona, California, Nevada, and New Mexico.
| Product Class | Where It Applies | Minimum SEER2 | Other Minimums |
|---|---|---|---|
| Split-system air conditioner | National (North region) | 13.4 | -- |
| Split-system air conditioner, less than 45,000 BTU/h | Southeast and Southwest | 14.3 | Southwest only: 11.7 EER2 (9.8 EER2 if certified SEER2 is 15.2 or higher) |
| Split-system air conditioner, 45,000 BTU/h and greater | Southeast and Southwest | 13.8 | Southwest only: 11.2 EER2 (9.8 EER2 if certified SEER2 is 15.2 or higher) |
| Split-system heat pump | National | 14.3 | 7.5 HSPF2 |
| Single-package air conditioner | National | 13.4 | -- |
| Single-package heat pump | National | 13.4 | 6.7 HSPF2 |
Federal and ASHRAE 90.1 IEER Requirements for Commercial Rooftop Units
For air-cooled commercial unitary air conditioners from 65,000 to 760,000 BTU/h, minimum efficiency is set by federal DOE standards (10 CFR 431.97), which preempt state and local efficiency levels for covered equipment. The levels below apply to equipment manufactured from January 1, 2023 through December 31, 2028; ASHRAE 90.1-2019 and 90.1-2022 incorporate these federal levels in their equipment efficiency tables. These IEER increases were negotiated through a DOE rulemaking in 2016 -- they were not introduced by the 2022 edition of 90.1.
| Cooling Capacity (BTU/h) | Heating Type | Minimum IEER (Air Conditioner) |
|---|---|---|
| 65,000 to < 135,000 | Electric resistance or no heating | 14.8 |
| 65,000 to < 135,000 | All other heating types | 14.6 |
| 135,000 to < 240,000 | Electric resistance or no heating | 14.2 |
| 135,000 to < 240,000 | All other heating types | 14.0 |
| 240,000 to < 760,000 | Electric resistance or no heating | 13.2 |
| 240,000 to < 760,000 | All other heating types | 13.0 |
IEER and Variable Speed
Because IEER rewards part-load performance, units with multiple compressor stages or variable-speed compressors and fans generally find it easier to meet these levels. When specifying replacement rooftop units, confirm the unit's certified IEER in the AHRI directory and check whether your adopted code edition sets any additional requirements. Air-cooled heat pumps have separate, slightly lower IEER minimums plus heating COP minimums.
Chiller Efficiency Requirements
Water-cooled and air-cooled chillers serving commercial buildings are subject to minimum full-load and integrated part-load value (IPLV) efficiency requirements in ASHRAE 90.1 Table 6.8.1-3. Air-cooled chillers are rated in EER (higher is better), while water-cooled chillers are rated in kW/ton (lower is better). The table offers two compliance options for most chiller types: Path A, which emphasizes full-load efficiency for chillers that run near full load, and Path B, which emphasizes part-load efficiency for chillers that run mostly at part load (typically with variable-speed drives). A chiller must meet both the full-load and IPLV values of the path it complies with. Requirements vary by compressor type, capacity band, and code edition, so pull the exact values from the table in the edition your jurisdiction has adopted rather than from summary charts.
HVAC Controls Requirements Under ASHRAE 90.1 and IECC
Minimum efficiency ratings alone do not satisfy code. ASHRAE 90.1 Section 6 and the IECC commercial provisions impose extensive controls requirements that must be met during design, installation, and commissioning.
Demand Control Ventilation
Demand control ventilation (DCV) automatically reduces outdoor air intake below design rates when actual occupancy is lower than design occupancy, cutting both heating and cooling energy. Under ASHRAE 90.1-2016, DCV was required for zones larger than 500 square feet with a design occupancy greater than 25 people per 1,000 square feet, where the HVAC system has an air-side economizer, automatic modulating outdoor air damper control, or a design outdoor airflow greater than 3,000 CFM (with several exceptions, including systems with qualifying energy recovery and systems under 750 CFM of design outdoor air).
The 2022 edition reworked the DCV requirement so that applicability depends on climate zone, ventilation airflow, and whether the space has energy recovery, using a new Table 6.4.3.8. The 2021 IECC lowered its own DCV trigger to spaces with 15 or more people per 1,000 square feet. Carbon dioxide (CO2) sensors are the most common DCV implementation method.
Economizer Requirements
Air-side economizers -- which increase outdoor air intake when outdoor conditions are favorable -- are required by ASHRAE 90.1 for cooling systems above a threshold capacity in most climate zones. ASHRAE 90.1-2013 required an air-side or water-side economizer on individual fan-cooling units of 54,000 BTU/h (4.5 tons) or more in all climate zones except 1A and 1B (very hot-humid and very hot-dry), and the standard lists many other exceptions. Check the economizer tables in your adopted edition for the exact thresholds.
Water-side economizers are also addressed for chilled water systems. Facilities in moderate-to-cool climates with central chiller plants can achieve significant energy savings through water-side economizer operation during winter and shoulder seasons.
Zone-Level Temperature Controls
Each independently controlled zone must have its own thermostat or zone controller. ASHRAE 90.1 Section 6.4.3 requires, among other controls:
- A dead band of at least 5°F between heating and cooling setpoints where a thermostat controls both (Section 6.4.3.1)
- Off-hour controls such as automatic shutdown and optimum start (Section 6.4.3.3)
- Setback controls that, during unoccupied periods, hold heating at an adjustable setpoint at least 10°F below the occupied heating setpoint and cooling at a setpoint at least 5°F above the occupied cooling setpoint (Section 6.4.3.3.2, as summarized by DOE for the 2016 edition)
Variable Air Volume and Fan Control
ASHRAE 90.1 Section 6.5.3 limits fan system power and requires variable-speed or equivalent fan control on VAV systems above size thresholds set in the standard. Starting with the 2019 edition, in-scope fans must also meet a minimum Fan Energy Index (FEI): 1.00 for constant-speed fans and 0.95 for VAV fans at design airflow. The 2021 IECC adopted similar FEI requirements.
Energy Management Control Systems
ASHRAE 90.1 Section 8.4.3 (in place since the 2013 edition) requires electrical energy monitoring in new buildings of 25,000 square feet or more. Electrical use must be monitored separately for total building energy, HVAC systems, interior lighting, exterior lighting, and receptacle circuits (and by tenant, where applicable), recorded at least every 15 minutes, and reported hourly, daily, monthly, and annually, with at least 36 months of data retained. The 2022 edition added refrigeration systems to the monitored categories.
Equipment Sizing Requirements
Oversized HVAC equipment is one of the most common compliance and performance failures in commercial buildings. ASHRAE 90.1 and the IECC both prohibit arbitrary oversizing by requiring equipment capacity to be determined through a formal load calculation.
Under 2021 IECC Section C403.1.1, heating and cooling design loads must be determined in accordance with ANSI/ASHRAE/ACCA Standard 183 or an approved equivalent procedure. Section C403.3.1 then limits equipment output capacity to the smallest available equipment size that exceeds the calculated loads. This prevents the common practice of "going up a size" for comfort margin and ensures equipment will operate at or near its rated efficiency more of the time.
Equipment sizing compliance is verified during the plan review and inspection process. Submittals must include load calculation documentation, and installed equipment nameplates must match specified capacities.
Energy Recovery Requirements
ASHRAE 90.1 Section 6.5.6.1 requires exhaust air energy recovery when a fan system's design supply airflow meets or exceeds the thresholds in Tables 6.5.6.1-1 and 6.5.6.1-2. Those thresholds depend on climate zone, the percentage of outdoor air at design conditions (starting as low as 10 percent), and whether the system operates fewer or more than 8,000 hours per year. There are numerous exceptions.
Under the 2016 edition, required systems must achieve an enthalpy recovery ratio of at least 50 percent. The 2022 edition added requirements for energy recovery bypass when economizing, including limits on bypass pressure drop and on energy exchange while in bypass mode.
For large commercial buildings with dedicated outdoor air systems (DOAS), ERV compliance is particularly important and must be demonstrated in the mechanical submittal through published equipment data matching the required effectiveness.
Commissioning Requirements
Who Must Commission
ASHRAE 90.1 and the IECC both require verification, functional testing, and (for larger projects) commissioning of HVAC systems, but the scope and formality depend on building size and system complexity. The 2019 edition of 90.1 expanded Section 4.2.5, "Verification, Testing, and Commissioning," and requires commissioning to follow ANSI/ASHRAE/IES Standard 202, The Commissioning Process for Buildings and Systems. It added Informative Appendix H with additional guidance.
Under 90.1-2016, HVAC commissioning was required only for buildings over 50,000 square feet. According to the committee's 2019 overview, 90.1-2019 lowered the commissioning documentation threshold to buildings over 10,000 square feet, with warehouses exempt and buildings with simple HVAC systems exempt up to 25,000 square feet. Functional testing of controls applies more broadly.
The 2021 IECC (Section C403.2.3) requires fault detection and diagnostics (FDD) for new buildings with 100,000 square feet or more of floor area. FDD uses permanently installed sensors to monitor HVAC performance, automatically identify and report faults, and notify operators.
What Commissioning Must Include
A compliant commissioning process under ASHRAE 90.1 includes:
- Owner's Project Requirements (OPR): A document defining the functional and performance requirements for the systems being commissioned, developed before design begins
- Basis of Design (BOD): Documentation explaining how the design meets the OPR
- Commissioning Plan: A detailed plan developed during design and updated through construction
- Functional Performance Testing: Verification that each HVAC component and sequence of operation performs as designed under representative operating conditions
- Preliminary Commissioning Report: Completed before occupancy, documenting all deficiencies and their resolution
- Final Commissioning Report: A complete record of all commissioning activities, test results, and outstanding deferred items
Commissioning Documentation
Retain all commissioning documentation for the life of the building. Some jurisdictions require commissioning reports to be submitted to the building department before a certificate of occupancy is issued. ASHRAE 90.1 applies to new construction and alterations; it does not set a periodic re-commissioning interval for existing buildings. Periodic retro-commissioning requirements, where they exist, come from local laws such as NYC Local Law 87.
Compliance Pathways
ASHRAE 90.1 and the IECC both offer multiple pathways to demonstrate compliance. Facility managers and design teams should understand the tradeoffs before selecting an approach.
| Compliance Pathway | Description | Best For | Key Limitation |
|---|---|---|---|
| Prescriptive Path | Each HVAC component individually meets minimum code requirements for efficiency, controls, and sizing | Straightforward projects with standard equipment selection | No tradeoffs allowed; every component must comply independently |
| Energy Cost Budget (ECB) Method (Section 12 in 90.1-2022; Section 11 in 90.1-2019) | Whole-building energy modeling demonstrates proposed design meets or is below a budget established by a code-compliant baseline building | Projects with non-standard systems or where tradeoffs are needed | Requires qualified energy modeler and simulation software that meets the standard's requirements |
| Performance Rating Method (Appendix G) | Whole-building modeling path that can show code compliance and is also used for above-code programs such as LEED | Projects that want one model for both code compliance and green building certification | Requires detailed energy modeling and documentation; confirm your jurisdiction accepts it |
| Total System Performance Ratio (TSPR) method (ASHRAE 90.1-2022, Normative Appendix L) | New optional path allowing tradeoffs within the HVAC system by comparing the proposed system's TSPR to a target | Projects where system-level efficiency exceeds prescriptive minimums | Newer method; confirm your jurisdiction's adopted edition includes it |
Common Compliance Failures and How to Avoid Them
Commercial HVAC energy code compliance failures fall into predictable patterns. Facility managers involved in new construction or major renovations should watch for these issues during design review and construction administration.
Incorrect efficiency rating verification. Equipment submittals must reference ratings from the AHRI directory or equivalent certified test data. Manufacturer's marketing literature is not sufficient. Confirm that the IEER, EER2, or COP values on the submittal match the installed model number in the AHRI database.
Missing or undersized economizers. Economizer requirements are frequently overlooked when equipment is selected from existing specifications or when replacing like-for-like. If the replacement system capacity exceeds the code threshold, an economizer may be newly required even if the original system did not have one.
Inadequate DCV sensor placement. CO2 sensors installed where they do not represent occupied-zone conditions provide inaccurate readings. Follow the sensor location and accuracy requirements of the adopted code and ASHRAE 62.1, and the manufacturer's installation instructions.
Unverified controls sequences. Installing controls hardware without functionally testing the sequences of operation can leave a project out of compliance with the code's verification and testing requirements. Thermostats, economizer controls, DCV sensors, and variable-speed drives must all be functionally tested with documentation.
Non-condensing boilers in larger new heating plants. ASHRAE 90.1-2022 (Section 6.5.4.8) requires new buildings with gas hot-water boiler systems for space heating with a total input of 1,000,000 to 10,000,000 BTU/h to achieve a minimum thermal efficiency of 90 percent, with design return water temperatures below 120°F -- which in practice means condensing boilers. Substituting non-condensing boilers where this applies creates a compliance problem.
Air Filter Efficiency Requirements
Air filtration requirements come mainly from ASHRAE 62.1 and the mechanical code rather than from the energy code, but filter selection affects fan energy. The Minimum Efficiency Reporting Value (MERV) scale defined in ASHRAE Standard 52.2 runs from 1 to 16, with higher values indicating higher capture efficiency for particles between 0.3 and 10 microns. EPA advises that when upgrading filtration, facilities choose at least MERV 13 or as high a rating as the system fan and filter slot can accommodate.
Facilities in healthcare, laboratory, and education occupancies often require higher MERV ratings per applicable occupancy codes. Facility managers should verify that specified filters match both the IAQ requirements of the occupancy and the pressure drop assumptions used in the HVAC system design -- higher-efficiency filters increase static pressure and must be accounted for in fan selection and energy modeling.
Key Compliance Timeline and Code Adoption Summary
| Code Edition | Publication Year | Key HVAC Changes | DOE Determination Status |
|---|---|---|---|
| ASHRAE 90.1-2016 | 2016 | Equipment efficiency updates, revised exhaust air energy recovery tables | Positive DOE determination; basis for many current state codes |
| ASHRAE 90.1-2019 / 2021 IECC | 2019 / 2021 | 90.1-2019: expanded verification, testing, and commissioning (Standard 202), Fan Energy Index. 2021 IECC: whole-building FDD at 100,000 sq ft, DCV at 15 people per 1,000 sq ft | Positive DOE determination; widely adopted baseline |
| ASHRAE 90.1-2022 / 2024 IECC | 2022 / 2024 | 90.1-2022: TSPR path, Section 11 energy credits, condensing-level boiler efficiency, climate-based DCV, refrigeration added to energy monitoring | DOE determination for 90.1-2022 issued March 6, 2024; adoption in progress across states |
| DOE Equipment Standards (effective Jan 2023) | 2023 | SEER2/EER2/HSPF2 metrics replace SEER/EER/HSPF for central air conditioners and heat pumps; higher federal IEER levels for commercial rooftop units | Federally mandated; applies to all manufactured equipment regardless of state code adoption |
Federal vs. State Requirements
Federal DOE minimum efficiency standards (SEER2, EER2, IEER) apply to covered equipment based on its date of manufacture, regardless of which state energy code edition has been adopted locally. A state may still be on an older edition of 90.1, but covered equipment manufactured today must still meet the current federal minimums. These are separate but overlapping requirements.
Action Steps for Facility Managers
Meeting commercial HVAC energy code requirements is an ongoing management responsibility, not a one-time design exercise. The following steps are recommended for facility managers responsible for HVAC compliance:
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Confirm your jurisdiction's adopted code edition. Contact your local building department or state energy office to determine the currently enforced edition of ASHRAE 90.1 or IECC and any local amendments.
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Maintain equipment records with rated efficiency values. For every installed HVAC unit, retain the AHRI-certified efficiency rating (IEER, EER2, COP, kW/ton), the installation date, and the code edition in effect at the time of installation.
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Plan periodic retro-commissioning. ASHRAE 90.1 does not set a re-commissioning interval, but drift in controls sequences, sensor calibration, and damper operation can degrade actual efficiency below design values. Some cities, such as New York under Local Law 87, mandate periodic retro-commissioning for large buildings.
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Review controls sequences annually. Verify that economizer controls, DCV sensors, setback schedules, and variable-speed drive programming are functioning as designed. Controls problems are a frequent cause of wasted energy in operating buildings.
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Engage an energy code consultant for major replacements. When replacing major HVAC plant equipment (chillers, boilers, rooftop units above 5 tons), engage a mechanical engineer or energy code consultant to confirm that the replacement equipment meets current code minimums and that any newly triggered requirements (economizers, ERV, commissioning) are addressed.
Sources and References
The following sources were used in the preparation of this article and are provided for further reference:
- ANSI/ASHRAE/IES Standard 90.1 -- Official ASHRAE Standard Page -- https://www.ashrae.org/technical-resources/bookstore/standard-90-1
- Standard 90.1-2022 Fact Sheet -- ASHRAE Government Affairs. https://www.ashrae.org/file%20library/about/government%20affairs/advocacy%20toolkit/virtual%20packet/standard-90.1-2022-fact-sheet.pdf
- Model Energy Code Determinations -- DOE Building Energy Codes Program. https://www.energycodes.gov/determinations
- Ten Things to Know About ASHRAE 90.1-2022 Updates -- Consulting-Specifying Engineer. https://www.csemag.com/ten-things-to-know-about-ashrae-90-1-2022-updates/
- ASHRAE Standard 90.1-2022 Webinar (November 16, 2023) -- DOE Building Energy Codes Program. https://www.energycodes.gov/sites/default/files/2023-11/ASHRAE90-1_2022_20231116_webinar.pdf
- Standard 90.1-2019 Webinar Presentation Slides -- DOE Building Energy Codes Program. https://www.energycodes.gov/sites/default/files/2020-06/Standard_90.1-2019_Webinar_Presentation_Slides.pdf
- ANSI/ASHRAE/IES Standard 90.1-2016: HVAC (PNNL for DOE BECP) -- Oregon Building Codes Division. https://www.oregon.gov/bcd/codes-stand/Documents/ashrae90.1-2016-hvac-final.pdf
- Airside Economizers and ASHRAE Standard 90.1-2013 -- Trane Engineers Newsletter. https://www.trane.com/content/dam/Trane/Commercial/global/products-systems/education-training/engineers-newsletters/airside-design/ADM-APN054-EN_05202015.pdf
- ASHRAE 90.1-2013 Section 8.4.3 Electrical Energy Monitoring (excerpt) -- https://ezmeter.com/wp-content/uploads/2022/07/ASHRAE-Chapter-8-Electric-Submeter-Specific-Regulations.pdf
- Top 10 Commercial HVAC Requirements: 2021 IECC -- Smart Energy Design Assistance Center, University of Illinois. https://smartenergy.illinois.edu/wp-content/uploads/2023/03/2021-IECC-Top-10_Commercial-HVAC_3.22.2023.pdf
- IECC 2021 HVAC Requirements for Commercial Buildings -- HVACProSales. https://hvacprosales.com/hvac-code-compliance/iecc-2021-hvac-requirements-for-commercial-buildings/
- 10 CFR 430.32 -- Energy and water conservation standards (central air conditioners and heat pumps) -- Cornell LII. https://www.law.cornell.edu/cfr/text/10/430.32
- 10 CFR 431.97 -- Energy efficiency standards for commercial air conditioning and heating equipment -- Cornell LII. https://www.law.cornell.edu/cfr/text/10/431.97
- ANSI/ASHRAE Standard 52.2-2017, Method of Testing General Ventilation Air-Cleaning Devices -- ASHRAE. https://www.ashrae.org/File%20Library/Technical%20Resources/COVID-19/52_2_2017_COVID-19_20200401.pdf
- What Is a MERV Rating? -- U.S. EPA. https://www.epa.gov/indoor-air-quality-iaq/what-merv-rating
