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WELL Building Standard: The WELL Air Concept

About WELL

The WELL Building Standard™ (version 2) aims to encourage the creation of spaces that enhance health and well-being. It includes a set of strategies, backed by scientific research, that improve health and wellness through design interventions and operational protocols and policies. 

Buildings and Wellness

The role buildings can play in health and well-being has never been more evident or more important. Thanks to recent research, we understand more about the relationship between the physical environment and human health than ever before. We know how to create spaces that enhance, rather than hinder, wellness. We can measure, and then improve, the quality of our air, water and light creating a space that will maximize benefits to productivity, well-being and health.

The Rating System

There are ten concepts in WELL v2, covering air, water, light, sound, movement and more. Each concept consists of features with distinct health intents and these features are either preconditions or optimizations, as discussed below. Projects must achieve all preconditions, as well as a certain number of points towards different levels of WELL Certification: Bronze, Silver, Gold and Platinum. 

The WELL Air Concept

People spend approximately 90% of their time in enclosed spaces – in homes, offices, schools or other building environments. During this time, inhalation exposure to indoor air pollutants can lead to a variety of negative health and well-being outcomes. The WELL Air concept aims to achieve high levels of indoor air quality across a building’s lifetime through diverse strategies. The goal is to deliver clean indoor air. 


The WELL Air concept aims to achieve high levels of indoor air quality across a building’s lifetime. The goal is to deliver clean indoor air.


Four Preconditions

The preconditions define the fundamental components of a WELL Certified space. They are the foundation of a healthy building. All preconditions, including all parts within them, are mandatory for certification.

1. Air Quality

Provide a basic level of indoor air quality that contributes to the health and well-being of building users.

Requirements: Meet thresholds for particulate matter, organic gases, inorganic gases and radon, and monitor air parameters. 

Note: Effective mechanical ventilation is particularly effective at bringing radon below acceptable thresholds.

2. Smoke-Free Environment

Deter smoking, minimize occupant exposure to second-hand smoke and reduce smoke pollution.

Requirements: Prohibit indoor and outdoor smoking. 

3. Ventilation Design

Minimize indoor air quality issues through the provision of adequate ventilation.

Requirements: Ensure adequate ventilation.

Note: In addition to proper HVAC system design, mechanically ventilated projects need to perform regular system maintenance.

4. Construction Pollution Management

Minimize the introduction of construction-related pollutants into indoor air, remediate construction-related indoor air contamination for human health and protect building products from degradation.

Requirements: Mitigate construction pollution.

Note: Air duct protection, moisture and dust management, filter replacement and proper equipment selection are recommended strategies that improve indoor air quality.

Ten Optimizations

Optimizations are optional pathways for projects to meet certification requirements in WELL. Project teams may select which optimizations to pursue and which parts to focus on within each optimization. 

1. Enhanced Air Quality (max 4 points)

Encourage and recognize buildings with enhanced levels of indoor air quality that promote the health and well-being of people. 

Requirements: Meet enhanced thresholds for particulate matter (2 points), organic gases (1 point) and inorganic gases (1 point).

2. Enhanced Ventilation Design (max 3 points)

Expel internally generated pollutants and improve air quality in the breathing zone through an increased supply of outdoor air or increased ventilation efficiency.

Requirements: Increase outdoor air supply (2 points) and increase ventilation effectiveness (1 point). 

Note: Advanced ventilation strategies that can achieve higher air quality levels include demand-controlled ventilation and displacement ventilation. 

3. Operable Windows (max 2 points)

Increase the supply of high-quality outdoor air and promote a connection to the outdoor environment, by encouraging building users to open windows when outdoor air quality is acceptable.

Requirements: Provide operable windows (1 point) and manage window use (1 point).

4. Air Quality Monitoring and Awareness (max 2 points)

Monitor indoor air quality issues, as well as inform and educate individuals on the quality of the indoor environment.

Requirements: Install indoor air monitors (1 point) and promote air quality awareness (1 point).

Note: Due to air quality fluctuations, it is important to install air quality sensors and detectors in every building. Because air quality can fluctuate throughout the day, real-time monitoring is necessary.

5. Pollution Infiltration Management (max 2 points)

Minimize the introduction of pollutants into indoor air through the building envelope and at building entrances.

Requirements: Design healthy entryways (1 point) and perform envelope commissioning (1 point). 

6. Combustion Minimization (max 1 point)

Reduce human exposure to combustion-related air pollution from heating and transportation sources.

Requirements: Manage combustion (1 point)

7. Source Separation (max 1 point)

Preserve indoor air quality and maximize olfactory comfort in occupied spaces through the isolation and proper ventilation of indoor pollution sources and chemical storage areas.

Requirements: Manage pollution and exhaust (1 point) 

Note: For air pollution sources that are inevitable, physical separation of such sources combined with direct ventilation exhaust systems is an effective means of protecting individuals.

8. Air Filtration (max 1 point)

Reduce indoor and outdoor airborne contaminants through air filtration.

Requirements: Implement particle filtration (1 point) 

Note: Installation of adequate media filters is one of the key mechanisms for minimizing exposure to air pollution. In addition, regular filter maintenance is critical to ensure proper air filtration and the efficiency of the air conditioning system.

9. Enhanced Supply Air (max 1 point)

Mitigate risks from indoor contamination and pollution sources, such as infectious disease particles and volatile organic compounds (VOC).

Requirements: Improve air supply (1 point) 

Note: This feature requires the projects to use supply air that is not recirculated or that is treated with carbon filters, media filters and/or Ultraviolet Germicidal Irradiation (UVGI).

10. Microbe and Mould Control (max 1 point)

Reduce mould and bacteria growth within the building mechanical system.

Requirements: Implement ultraviolet air treatment (1 point) 

Note: This feature requires projects to utilize UVGI systems and/or conduct regular inspections on components of the cooling system.

In Summary

It is clear that improving indoor air quality has a substantial impact on health and wellbeing. 

The World Health Organization has estimated that, globally, air pollution contributes to approximately seven million premature deaths a year. However, both professionals and building users need to put adequate measures in place to ensure high levels of indoor air quality.

The WELL Air Concept seeks to achieve the goal of clean indoor air through holistic design strategies. The overall aim is to minimize human exposure to harmful contaminants in order to maximize benefits to productivity, well-being and health.

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