Longevity Architecture
Terminology

Glossary

Clear definitions of the terms, concepts, and standards that constitute the vocabulary of longevity architecture.

ACH50 (Air Changes per Hour at 50 Pascals)

A standardized measurement of building airtightness. ACH50 quantifies how many times the total volume of air inside a building is replaced per hour when subjected to a pressure differential of 50 Pascals (typically via a blower door test). The IECC code minimum is 3.0 ACH50 for residential buildings. The Passive House standard requires 0.6 ACH50 or less, approximately 80% tighter than code. Lower ACH50 values indicate a tighter building envelope, which reduces uncontrolled air infiltration, moisture intrusion, and radon seepage.

ASHRAE 62.2

The American Society of Heating, Refrigerating and Air-Conditioning Engineers standard for residential ventilation. ASHRAE 62.2 specifies minimum ventilation rates for acceptable indoor air quality in low-rise residential buildings, typically calculated as 0.03 CFM per square foot of conditioned space plus 7.5 CFM per occupant. It provides the sizing basis for mechanical ventilation systems including HRV and ERV units.

Biophilic Design

An approach to architecture that incorporates natural elements, patterns, and processes into the built environment to support human health and wellbeing. Grounded in the biophilia hypothesis (the idea that humans have an innate affinity for nature), biophilic design encompasses direct nature contact (daylight, vegetation, water), indirect references (natural materials, organic forms), and spatial configurations that echo natural environments. A 2024 systematic review documented reduced hospitalization time, lower patient mortality, and measurable cortisol and HRV improvements in biophilic hospital environments.

Blower Door Test

A diagnostic procedure used to measure the airtightness of a building envelope. A calibrated fan is mounted in an exterior doorframe and depressurizes the building to 50 Pascals, while instruments measure the resulting airflow. The result, expressed in ACH50, reveals the total air leakage rate. Modern building codes (IECC) mandate blower door testing for new construction. For longevity homes, testing should occur both during construction (to identify and seal leaks) and post-construction (to verify performance).

Circadian Rhythm

The approximately 24-hour internal biological clock that governs sleep-wake cycles, hormone release, body temperature, metabolism, and immune function. Primarily entrained by light exposure, particularly the blue-enriched wavelengths present in morning daylight. Disruption of circadian rhythms is associated with sleep disorders, metabolic dysfunction, mood disorders, and increased cancer risk. A 2025 meta-analysis in Circulation Research documented 25 to 30% increased cardiovascular disease risk in individuals with chronic circadian misalignment.

Circadian Stimulus (CS)

A metric developed by the Lighting Research Center at Rensselaer Polytechnic Institute that quantifies the effectiveness of a light source in driving the human circadian system. CS values range from 0 to 0.7, with values above 0.3 considered effective for circadian entrainment. Used in architectural lighting design to evaluate whether a space provides adequate circadian light exposure.

COGfx Study

A series of controlled studies conducted by Harvard's T.H. Chan School of Public Health examining the effects of indoor environmental quality on cognitive function. The first study (2016) demonstrated that cognitive scores doubled in green building conditions with enhanced ventilation and reduced VOC concentrations.

Daylighting

The practice of placing windows, skylights, and reflective surfaces so that natural light provides effective internal illumination during daytime hours. In longevity architecture, daylighting is valued not only for energy efficiency and visual comfort but for its role in circadian entrainment and psychological wellbeing.

ELF-EMF (Extremely Low-Frequency Electromagnetic Fields)

Electromagnetic fields in the 3 to 300 Hz range produced by power lines, electrical wiring, transformers, and household appliances. Classified as a 'possible carcinogen' (Group 2B) by the International Agency for Research on Cancer. Health effects associated with chronic exposure include childhood leukemia (strongest evidence), brain and breast cancers, ADHD in prenatally exposed children, and cognitive decline. France recommends maintaining exposure below 0.4 microtesla in sensitive areas. In new construction, mitigation involves site planning (200+ meters from transmission lines), twisted-pair wiring, and strategic interior layout.

ERV (Energy Recovery Ventilator)

A mechanical ventilation system that exchanges stale indoor air for filtered outdoor air while recovering both heat and moisture (latent energy) from the exhaust stream. ERV systems are preferred in hot-humid climates (IECC zones 1 to 3) where they prevent excessive humidity buildup. Modern ERV systems achieve up to 80% energy recovery efficiency and reduce ventilation-related heating and cooling costs by 70 to 80%. When paired with IoT sensors, they can adjust ventilation dynamically based on CO2 levels, humidity, and occupancy.

FloorScore

A third-party certification program that tests flooring products for VOC emissions against the California Section 01350 standard. FloorScore evaluates 35 specific volatile organic compounds and is required for LEED v4 and WELL Building Standard compliance. Certified products emit 0.5 mg/m3 or less of total VOCs within 24 hours, compared to 1.5 to 3.0 mg/m3 for conventional flooring.

Grounding (Earthing)

The practice of establishing direct electrical contact between the human body and the earth's surface, either through barefoot contact with the ground or through conductive systems integrated into buildings. Emerging research (2024-2025) suggests that grounding transfers negatively charged electrons to the body, with measured physiological effects including inflammation reduction (confirmed via infrared imaging), improved heart rate variability, cortisol normalization, and a 13% decrease in blood viscosity. In new construction, grounding can be integrated through conductive flooring systems, sub-surface grounding layers, and grounding outlets for sleep areas.

Healthspan

The period of life spent in good health, free from chronic disease and disability. Distinguished from lifespan (total years lived), healthspan is the primary outcome metric for longevity-oriented design. The goal is not merely to extend life, but to extend the years of functional, healthy living.

HPA Axis

The hypothalamic-pituitary-adrenal axis: the body's central stress response system. Chronic activation of the HPA axis (by noise, poor air quality, thermal discomfort, or other environmental stressors) produces sustained cortisol elevation associated with cardiovascular disease, immune suppression, cognitive impairment, and accelerated aging.

HRV System (Heat Recovery Ventilator)

A mechanical ventilation system that exchanges stale indoor air for filtered outdoor air while recovering sensible heat from the exhaust stream. HRV systems are preferred in cold climates (IECC zones 6 to 8) where they recover heating energy. Distinguished from ERV systems, which also recover moisture. Modern HRV systems achieve greater than 90% heat recovery efficiency and are sized according to ASHRAE 62.2 ventilation requirements.

Indoor Environmental Quality (IEQ)

A comprehensive term encompassing the conditions inside a building that affect occupant health and comfort, including air quality, thermal conditions, lighting, and acoustics. IEQ is the primary domain of longevity architecture: the measurable interface between building design and human biology.

ipRGCs (Intrinsically Photosensitive Retinal Ganglion Cells)

A specialized subset of retinal cells containing the photopigment melanopsin. Unlike rods and cones (which serve vision), ipRGCs are primarily responsible for non-visual light responses including circadian entrainment, pupil constriction, and alertness regulation. They are most sensitive to blue-enriched light peaking around 480 nanometers. The discovery of ipRGCs fundamentally changed architectural lighting design by establishing that light serves biological functions beyond vision.

Melanopic Equivalent Daylight Illuminance (mel-EDI)

A metric that quantifies the biological potency of light for the human circadian system, specifically its effect on the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) that drive circadian entrainment. Recommended by the CIE (International Commission on Illumination) as the standard metric for circadian lighting design. The current recommendation is 250+ lux of melanopic EDI during daytime hours. A 2024 study documented a 52-minute increase in total sleep time at 238 melanopic-EDI lux combined with evening dim lighting.

Neuroarchitecture

An interdisciplinary field that applies neuroscience research to architectural design, studying how the built environment affects brain function, emotional states, and cognitive performance. Key brain regions include the parahippocampal place area (PPA), which links visual perception to spatial memory, and the hippocampus, which generates cognitive maps using place cells. Clear landmarks and legible layouts reduce cognitive load; confusing wayfinding activates stress responses. Practical applications now include customizable workspaces for neurodivergent individuals and sensory-retreat design in healthcare facilities.

Off-gassing

The release of volatile organic compounds (VOCs) from building materials, furnishings, and finishes into indoor air. Common sources include composite wood products (formaldehyde), paints and coatings (benzene, toluene), carpeting (4-phenylcyclohexene), and foam insulation (flame retardants). Off-gassing rates are typically highest when materials are new and decrease over time. Specifying 48 to 72 hours of continuous ventilation post-installation reduces VOC exposure by an estimated 60 to 80%.

Parahippocampal Place Area (PPA)

A brain region in the medial temporal lobe that responds selectively to images of places and scenes. The PPA links visual perception to spatial memory and plays a central role in how humans process and navigate architectural environments. Research in neuroarchitecture has shown that clear landmarks and legible building layouts reduce cognitive load and stress by supporting PPA function, while confusing wayfinding and monotonous corridors activate threat-detection systems.

Parasympathetic Activation

Engagement of the parasympathetic branch of the autonomic nervous system, the 'rest and digest' system that promotes recovery, digestion, and tissue repair. Architectural environments that support parasympathetic activation (through natural elements, appropriate acoustics, comfortable temperatures, and visual complexity) facilitate biological restoration.

Passive House (Passivhaus)

A rigorous, science-based building standard for energy efficiency and indoor environmental quality. Passive House certification requires air leakage of 0.6 ACH50 or less, heating demand of 15 kWh/m2/year or less (60 to 90% reduction versus conventional), cooling demand of 8 kWh/m2/year or less, and HRV/ERV systems with greater than 90% efficiency. A 2024 study of 600 homes found that Passive House occupants experience lower VOC concentrations, lower formaldehyde levels, lower radon levels, better humidity control, and lower CO2 concentrations than conventional homes. Construction premium is typically 4 to 6% above conventional, often recovered within 5 to 10 years through utility savings.

PFAS (Per- and Polyfluoroalkyl Substances)

A class of synthetic chemicals known as 'forever chemicals' because they persist indefinitely in the environment and accumulate in human tissues. Used in nonstick cookware, stain-resistant fabrics, and firefighting foams. PFAS contamination has been found in over 50 U.S. water supplies. Health effects include liver damage, immune system dysfunction, thyroid disorders, and increased cancer risk. Removal requires advanced filtration, typically reverse osmosis or granular activated carbon systems. Current EPA regulation covers only two specific PFAS compounds; hundreds remain unregulated.

Phygital

A term describing the convergence of physical and digital systems in the built environment. In longevity architecture, phygital integration encompasses AI-driven lighting systems that adjust spectrum based on circadian predictions, IoT environmental monitoring for real-time air quality and thermal optimization, and biometric feedback loops where wearable devices communicate with home systems to personalize lighting, temperature, and acoustic environments.

PM2.5

Particulate matter with a diameter of 2.5 micrometers or less: fine particles that penetrate deep into the lungs and can enter the bloodstream. Indoor sources include cooking, combustion, and infiltration from outdoor air. Chronic PM2.5 exposure is associated with cardiovascular disease, respiratory illness, cognitive decline, and reduced life expectancy.

Prospect and Refuge

A spatial configuration theory proposed by geographer Jay Appleton, suggesting that humans prefer environments that offer both prospect (open views, the ability to survey surroundings) and refuge (enclosed, protected spaces). Applied in architectural design to create spaces that feel both expansive and secure, a balance associated with reduced stress and increased comfort.

Rainscreen Design

A wall construction method that incorporates a drained and ventilated cavity between the exterior cladding and the weather-resistant barrier. The cavity allows any moisture that bypasses the outer layer to drain downward and dry through ventilation before reaching structural components. Rainscreen design is emerging as best practice (2024-2025) for longevity homes because it prevents moisture accumulation that leads to mold growth, structural degradation, and poor indoor air quality.

Regenerative Design

An architectural framework that goes beyond sustainability (minimizing harm) to create buildings that actively improve the environment and occupant health. Core principles include on-site energy generation (net-positive buildings), closed-loop water systems, bio-based materials with transparent supply chains, ecosystem integration through biophilic design and native landscaping, and adaptive resilience for climate change. Unlike 'healthy homes' that minimize toxin exposure, regenerative homes amplify wellness through systemic integration of improved air, water, light, materials, and ecosystem connection simultaneously.

RRNC (Radon-Resistant New Construction)

A set of construction techniques designed to prevent radon gas from entering a building through the foundation. RRNC methods include sub-slab depressurization systems (passive or active with fan), sump pit depressurization, crawl space encapsulation, and comprehensive foundation sealing. The EPA's Indoor airPLUS v2 standard (updated January 2024) requires radon control in all radon zones, not just high-risk areas. Post-construction testing is mandatory even in homes built with RRNC features. The EPA action level is 4 pCi/L, though mitigation is recommended between 2 and 4 pCi/L.

Salutogenic Design

Design that actively promotes health, as opposed to merely preventing disease. Derived from Aaron Antonovsky's concept of salutogenesis ('the origins of health'), salutogenic design focuses on creating environments that support physical, mental, and social wellbeing through positive environmental qualities rather than the elimination of hazards alone.

Sick Building Syndrome (SBS)

A condition in which building occupants experience acute health effects (headaches, eye irritation, fatigue, difficulty concentrating) that appear linked to time spent in a particular building but cannot be attributed to a specific illness or cause. Typically associated with poor ventilation, chemical contaminants, and inadequate indoor environmental quality.

Silent Architecture

An emerging design movement focused on minimizing noise exposure within the built environment. Silent architecture encompasses low-interference design (reducing mechanical noise from appliances and HVAC), sound-absorbing materials (felt, terra-cotta, organic textiles), and soft organic spatial forms (curved walls and layered facades). The movement responds to evidence that noise pollution is the second-largest environmental health threat in Europe, responsible for 12,000 premature deaths and 48,000 additional cases of ischaemic heart disease annually.

Soundscape

The acoustic environment as perceived by humans in context. Distinguished from 'noise' (unwanted sound), the soundscape concept recognizes that the quality and character of sound, not merely its level, affects human wellbeing. Soundscape design in architecture involves the intentional shaping of acoustic environments to support health, productivity, and comfort.

Sub-slab Depressurization

The most effective radon mitigation technique for residential construction. A network of perforated pipes is installed beneath the foundation slab, connected to a vertical vent pipe that extends through or alongside the building. In passive systems, natural stack effect draws radon-laden air upward and exhausts it above the roofline. Active systems add an inline fan for greater suction. Sub-slab depressurization prevents radon from entering living spaces by intercepting it before it passes through the foundation.

Thermal Comfort

The condition of mind that expresses satisfaction with the thermal environment. Influenced by air temperature, radiant temperature, air speed, humidity, metabolic rate, and clothing insulation. In longevity architecture, thermal comfort extends beyond satisfaction to encompass the health implications of thermal exposure, including the potential benefits of mild thermal variability.

Thermal Mass

The ability of a building material to absorb, store, and slowly release thermal energy. Materials with high thermal mass (concrete, masonry, rammed earth, water) moderate daily temperature swings by absorbing excess heat during warm periods and releasing it during cool periods. A 2024 systematic review documented average indoor temperature reductions of 2.2 degrees Celsius, 31% cooling load reduction, and 23% thermal comfort hour extension through passive thermal mass strategies. In longevity homes, exposed thermal mass in living areas reduces HVAC duty cycles, extends equipment life, and creates thermal stability that improves sleep quality.

VOC (Volatile Organic Compound)

A large group of carbon-based chemicals that evaporate easily at room temperature. Common indoor VOCs include formaldehyde, benzene, toluene, and xylene. Sources include building materials, furnishings, cleaning products, and personal care products. Indoor VOC concentrations are 2.5 to 5 times higher than outdoor levels regardless of geography. Chronic low-level VOC exposure is associated with respiratory irritation, neurological effects, neurocognitive impairment, and increased cancer risk.

WELL Building Standard

A performance-based certification system administered by the International WELL Building Institute (IWBI) that measures, certifies, and monitors building features that support human health and wellbeing. WELL v2 encompasses ten concepts: Air, Water, Nourishment, Light, Movement, Thermal Comfort, Sound, Materials, Mind, and Community. Each concept contains multiple features with specific performance thresholds verified through on-site testing and documentation review. WELL-certified buildings command 7.7% higher rental rates and show measurable improvements in occupant productivity, health, and wellbeing. The standard is now integrated into ESG reporting frameworks.