LEED vs. WELL Certification: Differences in Air Testing and Environmental Standards

Navigating the world of green building certifications can be complex, especially when comparing LEED vs. WELL certification. Both aim to create healthier, more sustainable spaces, but their approaches to aspects like air testing and environmental standards differ significantly. Discover which certification aligns best with your project's goals for indoor air quality and overall environmental performance.

Overview of LEED certification

LEED (Leadership in Energy and Environmental Design) is a globally recognized certification system for buildings and communities that evaluates their sustainability, energy efficiency, and overall environmental performance. Developed by the U.S. Green Building Council (USGBC) in 1998, LEED aims to promote building and operational practices that minimize environmental impact while supporting the well-being of occupants.

The system uses a point-based methodology, where projects must meet mandatory prerequisites and earn credits in various categories such as reducing energy and water consumption, using sustainable materials, improving indoor air quality, applying renewable energy, or facilitating access to public transportation. Certification can be awarded at four levels depending on the total number of points: LEED Certified (basic level of sustainability), LEED Silver, LEED Gold, and LEED Platinum (the highest level).

LEED is applicable to many types of projects – from new construction to existing buildings; commercial interiors; schools; homes; and even entire neighborhoods.

Overview of WELL certification

Developed by the International WELL Building Institute (IWBI), WELL Certification is a globally recognized healthy building certification program that focuses on enhancing the health and well‑being of people in buildings.

The program was launched in 2013 by Paul Scialla and the Delos company. It was the first standard focused specifically on occupant well‑being.

WELL certifications are performance‑based, meaning buildings must meet specific measurable standards that are verified by authorized agents. The program includes over 100 features (building attributes or strategies) grouped into preconditions (required for any certification level) and optimizations (optional improvements that increase your certification level).

WELL addresses seven broad concepts related to health and wellness, which typically include air, water, nourishment, light, fitness, comfort, and mind. Buildings or projects can be certified at different levels based on the points they score: Bronze, Silver, Gold, and Platinum.

On average it takes about six months from start to finish to achieve WELL certification. Like other programs it involves third‑party performance verification by authorized agents.

Environmental focus of LEED vs. health focus of WELL

The primary distinction between LEED and WELL certifications is that LEED prioritizes environmental performance while WELL prioritizes human health and wellness.

LEED (Leadership in Energy and Environmental Design) addresses a building’s environmental impacts by emphasizing energy efficiency, water conservation, sustainable site development, and the use of renewable energy. In contrast, WELL Certification addresses human health and wellness within the building by prioritizing indoor air and water quality, natural light, thermal comfort, opportunities for physical activity, and mental well-being.

Both certifications promote sustainable and healthy building practices but from complementary perspectives: LEED focuses on how the building impacts the outside environment and surrounding context; WELL focuses on how the building impacts its occupants.

How air quality is measured in LEED and WELL

In LEED, particularly in LEED v5, indoor air quality is assessed through testing and monitoring of specified pollutants. These include particulate matter (PM2.5 and PM10), carbon monoxide (CO), and ozone (O3).

WELL places a strong emphasis on continuous monitoring and precise data collection to support occupant health. It monitors particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), inorganic gases such as carbon monoxide (CO) and ozone (O3), as well as radon.

For specific pollutant thresholds, see also the benefits of each certification regarding indoor air quality.

Both LEED and WELL focus on ensuring good indoor air quality by monitoring key pollutants such as PM2.5, CO, VOCs. A key difference is that WELL additionally includes radon monitoring which is not explicitly mentioned in LEED v5.

Certification frameworks and processes

Distinct processes, pathways, and verification methods are utilized by LEED and WELL certification frameworks, each reflecting its respective core goals.

LEED points-based system

The LEED points-based system awards points to building projects across 8 to 9 sustainability categories, with a maximum of 110 possible points. To qualify for certification, projects must first meet mandatory prerequisites. Once those are satisfied, projects earn credits by implementing sustainable design strategies; these credits correspond to points.

The total number of points earned determines the certification level:

• Certified: 40-49 points

• Silver: 50-59 points

• Gold: 60-79 points

• Platinum: 80 or more points

A LEED scorecard breaks down the available points by category, allowing project teams to easily track their progress from design through construction.

WELL performance-based system

Through on-site testing, sensor data, and occupant feedback, the WELL performance-based system verifies that buildings meet specific, measurable standards for health and wellbeing. The system covers seven main action areas:

• Indoor Air Quality

• Water Quality Management

• Lighting Measurement

• Thermal Conditions

• Acoustic Performance

• Environmental Monitoring

• Occupant Experience.

The buildings are evaluated using a combination of on-site tests conducted by trained professionals; permanently installed sensors that collect ongoing data; and occupant surveys. To achieve the WELL Performance Rating, a building must successfully meet 21 features. Buildings that meet these requirements receive a WELL Performance seal demonstrating that they satisfy recognized health standards.

Recertification requirements

To remain valid, LEED certifications for existing buildings must be recertified every 3 to 5 years. Under LEED v4.1, recertification is required every 3 years. For LEED recertification, building teams submit updated performance data across categories such as energy, water, waste, transportation and human experience.

WELL certifications are granted for a period of 3 years after which recertification is required to maintain certification. WELL recertification generally requires demonstrating continued operational performance of health and wellness features and may include on-site performance verification.

Similarities between LEED and WELL standards

LEED and WELL are certification systems that use a structured process to evaluate and recognize buildings as environmentally and socially responsible. Each operates a formal certification program in which projects are assessed against defined standards, consisting of prerequisites and credits.

Both systems emphasize indoor air quality – they require air management plans, measures to reduce volatile organic compounds (VOCs), and appropriate air filtration. They also address water-related issues – LEED focuses on water conservation, while WELL emphasizes water quality.

Since their scopes are complementary, the International WELL Building Institute (IWBI) and the U.S. Green Building Council (USGBC) have established a streamlined process for projects seeking both certifications simultaneously.

Benefits of LEED certification

LEED-certified buildings use significantly less energy and water (average energy consumption is reduced by 25-60%), which lowers operational costs. By using less energy and producing fewer emissions, LEED certification reduces pollution and the building’s overall carbon footprint.

LEED-certified buildings use pollution-free materials and incorporate designs that maximize natural daylight and ventilation, improving indoor air quality.

LEED-certified buildings often qualify for tax incentives, have 15-20% lower maintenance costs, and can increase property value by around 10% or more. Investors and companies also use LEED as a framework to meet Environmental, Social, and Governance (ESG) goals.

The healthier, more comfortable building environment in LEED-certified buildings can improve employee satisfaction, reduce sick days, and aid recruitment/retention efforts.

Benefits of WELL certification

Compared to non-certified buildings, WELL-certified spaces have around 12% fewer complaints related to Sick Building Syndrome. People working in these buildings also report being more satisfied with their work environment, and as a result, such spaces can boost employee productivity and creativity.

WELL certification is the first building standard focused entirely on human health. By achieving it, your organization demonstrates that you prioritize employee health and are committed to creating a culture of wellness that spans all departments.

The certification is awarded by an independent organization after a thorough documentation review and onsite verification. Being WELL-certified can also enhance your company’s brand reputation and provide a verified baseline for Environmental, Social, and Governance (ESG) reporting.

Dual certification: combining LEED and WELL

Dual certification is when you pursue LEED and WELL for the same project. LEED is known for environmental sustainability, while WELL is known for human health. LEED targets lower environmental impact, while WELL targets occupant health and comfort. Combining them results in a building that’s good for both the planet and its people.

The U.S. Green Building Council (USGBC) and the International WELL Building Institute (IWBI) have recognized this trend and developed official crosswalks between the two rating systems, as well as a streamlined certification pathway to reduce complexity.

Hundreds of projects around the world have pursued both certifications simultaneously or sequentially, demonstrating strong market demand. Dual certification can also signal leadership in both areas, making your project more attractive to tenants and other stakeholders.

How to choose between LEED and WELL for your project

When to choose LEED vs WELL:

• Choose LEED certification when your priority is to create a green building that uses fewer resources and causes less environmental harm.

• Choose WELL certification when your objective is to enhance occupant comfort, mental and physical health, and productivity.

• If you’re working on a project such as a healthcare facility or office that has both environmental and occupant health objectives, pursuing both certifications can be beneficial.

• WELL certification involves more performance-based testing after occupancy (including onsite verification of air and water quality), whereas LEED certification is more focused on design and construction documentation.