Quality of Life (QoL) and Indoor Environmental Quality (IEQ)

Quality of Life (QoL) and Indoor Environmental Quality (IEQ) are directly connected. In fact, IEQ is one of the most fundamental and influential factors affecting our daily QoL.

🌿 1. What is IEQ?

IEQ – Indoor Environmental Quality refers to the combined physical, chemical, and biological conditions that affect human perception and health in indoor spaces such as living, working, or learning environments.

Main Components	Specific Factors	Objectives
Indoor Air Quality (IAQ)	CO₂, VOCs, fine dust, formaldehyde (HCHO), microorganisms, ventilation	Promote fresh breathing, reduce fatigue, increase focus
Lighting Quality	Natural light, light spectrum, glare control, circadian lighting	Balance biological rhythm, enhance productivity, reduce stress
Acoustics	Noise, reverberation, sound insulation	Reduce stress, improve concentration and privacy
Thermal Comfort	Temperature, humidity, air speed, radiation	Create comfort, reduce physiological fatigue
(Optional: Visual & Spatial Quality)	Colors, materials, form, view to nature	Enhance positive emotions and sense of well-being

💓 2. IEQ and Physical Health

Research from WELL, WHO, and ASHRAE shows:

Factor	Health Impact
Poor IAQ	Respiratory illness, allergies, headaches, Sick Building Syndrome (SBS)
Lack of natural light	Sleep disorders, low vitamin D, weakened immunity
Extreme temperatures	Circulatory issues, fatigue, poor concentration
Constant noise	High blood pressure, stress, reduced performance
Lack of biophilic connection	Increased anxiety, slower recovery after illness

👉 Overall result: People living in spaces with good IEQ experience 30–50% fewer health problems and a noticeable increase in daily vitality.

🧘‍♀️ 3. IEQ and Mental–Emotional Well-being

Our living space acts as an “energy field” that directly influences the mind.

IEQ Component	Psychological Effect
Natural light	Regulates circadian rhythm → better sleep, less depression
Natural ventilation & fresh scent	Feelings of liveliness, reduced stress, higher alertness
Natural sounds (wind, water, birds)	Aids meditation, lowers cortisol, promotes calmness
Natural materials & soft colors	Evoke safety, comfort, and a sense of belonging
Open space & distant view	Foster freedom, reduce psychological pressure

👉 The WELL Building Standard emphasizes: “Environment is the foundation of sustainable mental health.”

💼 4. IEQ and Productivity / Learning

Surveys in the U.S., Japan, and Singapore reveal:

🌬 Improving IAQ (reducing CO₂ from 1200 ppm to 600 ppm) → 8–11% productivity increase
💡 Optimizing lighting for circadian rhythm → 23% better focus, 18% fewer mistakes
🔇 Reducing unwanted noise → 10–20% higher efficiency
🌡 Maintaining thermal comfort (22–26°C) → 2–4% productivity boost

=> A good IEQ space is not only “comfortable” but also delivers tangible economic benefits through performance.

🌏 5. IEQ → Well-being → Quality of Life (QoL)

The relationship can be described as:

Good Physical Environment (IEQ)
→ Sense of comfort and safety
→ Balance of body – mind – spirit
→ Enhanced creativity, productivity & social interaction
→ Formation of a sustainable Quality of Life

In other words:

“When people live in a healthy environment, they are not only healthier — they live more deeply and meaningfully.”

🌱 6. Conceptual Model Summary

Level	Component	Main Impact	Final Outcome
1️⃣ IEQ (Physical)	Air, light, sound, temperature, space	Physical comfort
2️⃣ Human (Physiological–Psychological)	Health, sleep, emotion, focus	Performance, creativity, happiness
3️⃣ QoL (Quality of Life)	Inner peace, connection, freedom	Sustainable, meaningful life	Peace & holistic development