InterNACHI Well key terms

A performance-based rating system that scores buildings on features affecting occupant health and well-being across air, water, light, nourishment, movement, thermal comfort, sound, materials, mind, and community.

A single numbered requirement within the WELL standard, grouped under a concept, that a project must satisfy and document to earn points or meet a precondition.

A mandatory WELL requirement that must be met for a project to achieve certification at any level; unmet preconditions block certification regardless of points earned.

A WELL feature that awards points toward a certification level but is not mandatory; projects select optimizations to accumulate the score needed for their target level.

The tier a project achieves based on total points earned after all preconditions are met, typically Bronze, Silver, Gold, and Platinum as defined by the applicable WELL version.

A credentialed professional who has passed the WELL Accredited Professional exam and is recognized for knowledge of the standard; the credential is held by individuals, not buildings.

The stage in which an independent reviewer or WELL assessor checks on-site performance through testing, measurement, and document review before certification is granted.

A random or targeted on-site verification performed during performance verification to confirm that installed conditions match the documentation a project submitted.

The written, photographic, and data evidence a project submits to demonstrate that each feature is designed, installed, and operating as the standard requires.

A signed declaration from a manufacturer, contractor, or owner confirming that a product, system, or condition meets a specified WELL requirement.

The volume of outdoor air supplied to a space per unit time, usually expressed in liters per second per person or air changes per hour, used to dilute indoor pollutants.

The number of times the total volume of air in a space is replaced in one hour; a common metric for ventilation adequacy and for isolation-room design.

A control strategy that modulates outdoor air delivery based on measured occupancy or pollutant indicators, such as carbon dioxide sensors, rather than a fixed schedule.

Continuous measurement of indoor CO2 concentration as a proxy for occupancy and ventilation effectiveness, often used to trigger increased outdoor air or alert operators.

Fine particulate matter with aerodynamic diameter of 2.5 micrometers or less, capable of penetrating deep into the lungs; a key outdoor and indoor air quality metric.

Removal of particles and some gases from air or water by passing them through a medium; effectiveness is rated by metrics such as MERV for air filters.

Minimum Efficiency Reporting Value, a scale from 1 to 16 (and higher in extended ratings) describing how well an air filter captures particles of specified size ranges.

A public scale reporting outdoor pollutant concentrations and associated health risk; WELL projects may use it to decide when to close outdoor air intakes or increase filtration.

Design measures at building entrances, such as vestibules, grilles, or mats, that limit outdoor pollutants, moisture, and dirt from being tracked or drawn into occupied spaces.

The aggregate concentration of volatile organic compounds measured in indoor air or emitted by a product, used as a screening indicator of chemical load.

The mass of volatile organic compounds present in a product formulation per unit volume or mass, as declared by the manufacturer or regulated by local rules.

Laboratory chamber testing that measures the rate at which a product releases volatile compounds into air over time, producing concentration data used for product qualification.

A colorless, irritant gas emitted by some composite wood, adhesives, and furnishings; a regulated indoor carcinogen that WELL limits through product and testing requirements.

A toxic heavy metal that can leach into drinking water from pipes, solder, and fixtures; WELL water features address it through testing, filtration, and fixture selection.

Treatment of drinking water through media, membranes, or carbon to reduce contaminants such as sediment, chlorine, lead, and microorganisms before consumption.

Sampling and laboratory analysis of drinking water for parameters such as turbidity, metals, disinfection byproducts, and microbial indicators to confirm compliance.

The provision of conveniently located, free, palatable water dispensers so occupants can refill containers without relying on bottled or sugary beverages.

The condition of mind that expresses satisfaction with the thermal environment, influenced by air temperature, radiant temperature, humidity, air speed, and clothing.

A thermal comfort index predicting the average occupant sensation on a seven-point scale from cold to hot, calculated from environmental and personal variables.

The amount of water vapor in air expressed as a percentage of the maximum it could hold at that temperature; extremes affect comfort, mold, and respiratory health.

Design and operational measures that keep building materials dry and humidity controlled, preventing fungal growth that harms air quality and occupant health.

Detailing of envelopes, roofs, plumbing, and drainage to prevent water intrusion and condensation, protecting materials and indoor air quality over the building life.

Computer simulation that predicts interior daylight levels across a space, used to demonstrate targets such as spatial daylight autonomy or illuminance thresholds.

The percentage of floor area that receives a target daylight illuminance for a specified fraction of occupied hours, typically evaluated annually by simulation.

Design measures such as shading, blinds, light shelves, and luminaire selection that reduce visual discomfort from excessive brightness or contrast in the field of view.

Electric or daylight design that delivers appropriate light intensity and spectrum over the day to support the body's sleep-wake rhythm, especially morning bright light.

A metric expressing how strongly a light source stimulates the melanopsin-containing retinal cells that regulate circadian timing, weighted for that response.

Design and policy strategies that make healthier food and drink the easy choice, such as visible fruit, reduced sugary beverage marketing, and nutritional labeling.

Building and site strategies that encourage physical activity, including prominent stairs, walking routes, bicycle storage, and exercise spaces for occupants.

Programs and communications that inform and involve building users in health-related behaviors and building performance, such as surveys, guides, and feedback loops.

A structured questionnaire administered after occupancy to measure satisfaction with comfort, acoustics, lighting, and other conditions, informing corrective action.

The degree to which the sound environment supports speech privacy, concentration, and rest, achieved through absorption, blocking, and background noise control.

Introduction of low-level broadband background sound to reduce the intelligibility of nearby speech and improve privacy in open or shared spaces.

The time required for sound to decay by 60 decibels after a source stops, used to gauge how much sound absorption a room needs for clarity and comfort.

A quality-assurance process that verifies building systems are designed, installed, and operating according to the owner's requirements and the project's health goals.