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In April 2025, the U.S. Green Building Council (USGBC) officially released v5 of the Leadership in Energy and Environmental Design (LEED) Certification. Compared to LEED v4.1, LEED v5 places a stronger emphasis on a number of green and healthy building initiatives, most notably indoor air quality (IAQ).
How Is Indoor Air Quality in LEED v5 Different From LEED v4.1?
The major difference between LEED v4.1 and LEED v5 is the higher number of points awarded for real-time, continuous monitoring of IAQ. There are more points available for this type of monitoring than periodic air testing. This is great news — instead of performing regular spot-checks, continuous monitoring offers a much easier and less time-consuming way to achieve maximum points for IAQ.
LEED v5 also offers additional points for a range of IAQ improvement strategies, including outdoor air quality monitoring, compliance with ASHRAE 241, and exceeding minimum standards for ventilation, filtration, and air quality parameters, among others.
What is LEED v5?
LEED is the most globally recognized green building certification, boasting over 100,000 certified buildings worldwide. Established in 1998, the standard has increasingly emphasized indoor air quality (IAQ) over the years.
LEED has evolved through several versions since its launch in 1998. LEED v4 was introduced in 2013, and its successor, v4.1, entered Beta in 2019 but never progressed beyond this stage. It was officially replaced with LEED v5, which was released on April 28, 2025.
This article focuses on a detailed comparison between the IAQ requirements in LEED v4.1 and the upgrades in the LEED v5. The analysis will be separated into two parts: Building Operations + Maintenance (O+M): Existing Buildings, and Building Design + Construction (BD+C): New Construction.
But first, let’s dive into some background on why LEED is expanding its focus on IAQ, and how v4.1 serves as a jumping-off point for v5’s IAQ requirements.
The Importance of Indoor Air Quality
IAQ is critical for human health, comfort, performance, and productivity. Poor IAQ can lead to a range of health issues, including respiratory problems and allergies, and massively impact cognitive performance. A high-performing building should not only be environmentally sustainable but also serve and promote the health and well-being of its occupants. Learn more about the impact of IAQ on our health, productivity, and workplace experience here.
IAQ in LEED O+M Certification
LEED v4.1
Indoor Environmental Quality (IEQ) is one of seven core categories that make up the LEED program and is intended to reward positive design choices and operation strategies that emphasize the health and comfort of building occupants.
IAQ in v4.1 is primarily addressed by the Indoor Environmental Quality Performance prerequisite. This credit requires buildings to conduct an occupant satisfaction survey and/or an indoor air quality evaluation.
This credit awards points for the annual measurement of CO2 and TVOC. These two readings are combined with the score from an annual occupant survey to output a final score. The weighting is 50% IAQ measurements and 50% survey results.
Limitations of LEED v4.1 Approach
- A very limited range of IAQ parameters are measured. For example, PM2.5, a harmful pollutant, is not included in the assessments.
- Annual readings offer an incomplete picture of IAQ.
- Overemphasis on occupant surveys: Human perception is not reliable for detecting harmful pollutants, yet it accounts for 50% of the score.
LEED v5
As with previous versions, LEED v5 also has an IEQ core category, within which several credits addressing air quality are found.
EQ Prerequisite: Verification of Ventilation and Filtration
The intent of this new prerequisite is to understand the amount of outdoor air being delivered by the ventilation systems, exhaust, and filtration, and compare it to ventilation standards for IAQ.
For mechanically ventilated space, this is essentially a benchmarking against ASHRAE 62.1. The nuance in this credit is that ventilation data must be measured, and recommendations and potential corrective actions identified, but changes are not required. The rating of MERV filters installed must also be calculated, and usage of MERV 13 filters is recommended, but not mandated.
EQ Credit: Indoor Air Quality Performance (Up to 10 Points)
This is the major update, and something that should get every building operator excited!
The intent of this credit is to support indoor air quality awareness, identify opportunities for IAQ improvements, and to promote occupants’ comfort, well-being, and productivity via IAQ. The credit can deliver a project a total of 10 points, available through three different options:
Option 1. Continuous Indoor Air Monitoring (1-10 Points)
Option 1 is a major update that allows continuous monitoring of IAQ (specifically CO2, PM2.5, and TVOC) to earn up to 10 points. You automatically earn two points each by installing monitors that measure these parameters, but can earn up to four additional points by meeting certain thresholds for CO2 and PM2.5.
| Parameter | Benchmark | LEED Points |
| Carbon dioxide (CO2) | > 1000 ppm | 2 |
| 1000 ppm | 3 | |
| 800 ppm | 4 | |
| PM2.5 | > 15 µg/m3 | 2 |
| 15 µg/m3 | 3 | |
| 12 µg/m3 | 4 | |
| TVOC | Any level | 2 |
The key takeaway here is that using a continuous air quality monitor that measures CO2, TVOC, and PM2.5 and meeting certain thresholds for these parameters can deliver the maximum of 10 points. The new thresholds generally align with WELL v2. Note that a RESET or UL2905-certified monitor must be used for measurement in this option.
Be sure to review LEED v5’s requirements for IAQ monitor density, location, and distribution before mapping your sensors. Following these guidelines will ensure that you capture a complete picture of your building’s air quality. At a minimum, one monitor should be placed every 25,000 ft2 (2,500 m2) in the breathing zone, and you should ideally install monitors across different floors, space types, HVAC zones, etc. Read more about how to meet LEED v5’s requirements for air quality monitor density and placement.
Option 2. Targeted One-Time Air Testing (1-3 Points)
Projects can earn up to three points for this credit by conducting an annual air quality test and meeting the minimum IAQ limits (using outdoor air quality readings as a reference). Both laboratory-based and direct-read test methods are allowed.
| Parameter | Concentration limit (µg/m3) |
| Carbon monoxide (CO) | 9 ppm and no more than 2 ppm above outdoor levels |
| Particulates: PM10 |
ISO class 8 or lower per ISO 14644-1:2015 OR Meet 50 µg/m3 |
| Particulates: PM2.5 |
ISO class 8 or lower per ISO 14644-1:2015 OR Meet 12 µg/m3 OR For projects located in an area where the national standard for PM2.5 is exceeded, meet 35 µg/m3 Note: Cannot earn points if already continuously monitoring |
| Ozone | 0.07 ppm |
| Nitrogen dioxide (NO2) | 40 µg/m3 (21 ppb) |
| TVOC | N/A (Cannot earn points if already continuously monitoring) |
Option 3. Targeted One-Time Individual Volatile Organic Compounds Testing (2 Points)
Two points can be earned by testing for all volatile organic compounds (VOCs) at least once per year in an accredited laboratory, and by demonstrating that no VOCs exceed their concentration limit.
| Contaminant (CAS#) | Concentration limit(µg/m3) |
| TVOC | Investigate and take corrective action if levels exceed 500 µg/m3 |
| Formaldehyde 50-00-0 | 20 µg/m3 (16 ppb) |
| Acetaldehyde 75-07-0 | 140 µg/m3 |
| Benzene 71-43-2 | 3 µg/m3 |
| Hexane (n-) 110-54-3 | 7,000 µg/m3 |
| Naphthalene 91-20-3 | 9 µg/m3 |
| Phenol 108-95-2 | 200 µg/m3 |
| Styrene 100-42-5 | 900 µg/m3 |
| Tetrachloroethylene 127-18-4 | 35 µg/m3 |
| Toluene 108-88-3 | 300 µg/m3 |
| Vinyl acetate 108-05-4 | 200 µg/m3 |
| Dichlorobenzene (1,4-) 106-46-7 | 800 µg/m3 |
| Xylenes — total 108-38-3, 95-47-6, and 106-42-3 | 700 µg/m3 |
IAQ in LEED BD+C Certification
LEED v4.1
Indoor Environmental Quality (IEQ) is one of nine core categories that make up the LEED BD+C certification. In LEED v4.1, there is one prerequisite and three credits for air quality. The prerequisite requires compliance with ASHRAE 62.1 for mechanically and naturally ventilated spaces, and the three credits provide additional points for enhanced IAQ strategies, IAQ management plans during construction, and post-construction air quality assessments.
The highest number of points can be scored with the Enhanced Indoor Air Quality Strategies credit (up to 2 points) and Indoor Air Quality Assessment credit (up to 2 points). Both credits have multiple options to score maximum points, with only 6 out of 10 enhanced IAQ strategies required for full points, and either building flush-outs or IAQ spot-checks required for maximum points for the assessment credit.
Limitations of LEED v4.1 Approach
- Allows buildings to pick and choose the IAQ parameters they want to measure, instead of measuring all relevant parameters
- Air quality assessments are either flush-outs or measurements of certain IAQ parameters, which gives the option to not measure air quality at all
- Measuring IAQ parameters for the air quality assessment only requires spot-checking, which is less accurate and reliable than continuous monitoring
LEED v5
IEQ is also a core category in LEED v5 BD+C: New Construction, with one prerequisite and two credits related to IAQ, offering three possible points.
EQ Prerequisite: Fundamental Air Quality
LEED v5 requires buildings to meet baseline IAQ standards both during and after construction to safeguard occupant health and well-being, with a particular focus on PM2.5 that is created by construction work. This prerequisite includes five requirements that also use ASHRAE Standard 62.1 as a benchmark.
These requirements in this prerequisite are generally preventative — implementing entryway systems to collect dirt and other particulates, and ensuring that ventilation and filtration systems that deliver outdoor and/or recirculated air to regularly occupied spaces comply with ASHRAE 62.1.
EQ Credit: Enhanced Air Quality (Up to 1 Point)
This credit aims to enhance IAQ to protect occupants from adverse health effects of poor air quality. There are two ways to achieve the point for this credit:
1. Increase ventilation rates by at least 15% in 95% of all regularly occupied spaces.2. Meet the design limits for enhanced indoor air quality design:
| Design compound orPM2.5 | Enhanced IAQP design limit |
| PM2.5 | 10 µg/m3 |
| Formaldehyde | 20 µg/m3 |
| Ozone | 10 ppb |
EQ Credit: Air Quality Testing and Monitoring (Up to 2 Points)
This credit is where continuous air quality monitoring comes into play, not only to optimize air quality management but to also find opportunities to make building design more health-focused. There are three options to achieve points for this credit.
Option 1. Pre-Occupancy Air Testing (Up to 2 Points)
Once construction has been completed, and the building is able to maintain ventilation conditions that are typical during expected occupancy levels, perform a baseline IAQ test before occupants enter the building. The number of measurements ranges from 1 to 10, depending on the total occupied floor area of the building.
The first path (one point) you can take is measuring particulate matter and inorganic gases over an 8-hour period, using an ISO-accredited laboratory to calculate peak concentrations for carbon monoxide (CO), PM 10, PM2.5, and ozone.
The second path (one point) is testing an air sample for VOCs to ensure each compound remains within the required concentration limit and the TVOC level remains below 500 µg/m3. If any parameters exceed their prescribed limits, the problem must be fixed and the building has to be re-tested before earning the point.
Option 2. Continuous Indoor Air Monitoring (Up to 1 Point)
Instead of performing spot-checks in option 1, buildings can instead install IAQ monitors that continuously measure CO2, PM2.5, TVOC, temperature, and relative humidity. These monitors must be RESET or UL2905-certified and installed 3-6 feet above the floor.
How to Achieve Maximum Points for IAQ In LEED v5
There are multiple pathways to achieving the full points for indoor air quality in LEED v5. Here’s our recommendation for the most effective way to maximize your points:
| LEED v5 O+M | LEED v5 BD+C |
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Implications for Building Owners and LEED v5 Applicants
This is a monumental advancement for LEED, the IAQ industry, and, most importantly, the health of building occupants. The shift from periodic checks to continuous monitoring signifies a pivotal moment for the industry. As more buildings start to pursue LEED v5 certification, continuous monitoring is positioned to become the standard practice for air quality management and optimization.
In summary, continuous monitoring is poised to become the standard practice for all future LEED v5 buildings.
Discover the latest innovations in LEED v5 and the updates to indoor air quality that have come with it in our on-demand webinar: Exploring LEED v5: The Latest IAQ Updates and Improvements
