The big picture for IEQ

With an extreme focus and rapid development in recent decades (in research, industries and all types of buildings), indoor air quality (IAQ) is often misused as a substitute for indoor environmental quality (IEQ).

It has been complicated...

  • From bad air indoors to polluted air in cities, from dampness in buildings to problems with hygiene. 
  • Poor air, poor ventilation and poor temperature. 
  • The impact of fresh air, hygiene, sunlight and natural ventilation. 
  • From IAQ and energy efficiency to IEQ and health.

How it all began...

Many thousands of years ago, when humans started to live in caves and the air was polluted by fires used for cooking, emitting lots of smoke - people spent more time outside (hunting for food, collecting water and playing), so the effects of the bad air were not immediately visible.

Jump to a few hundreds of years before Christ and there was polluted air in crowded cities, dampness in buildings and problems with hygiene and more.

Only a few hundreds years before the 20th century, the health effects of poor air, poor ventilation and poor temperature were also responsible for the spread of various diseases.

Only around the 18-19th century,  the impact of fresh air, hygiene, sunlight and natural ventilation were pioneered by the famous nurse, Florence Nightingale. This slowly led to a better understanding and connecting the dots of how the IEQ impacts humans and subsequent changes started to occur.

Move to the 19-20th centuries, when many great debates were focused on CO2 (ppm), airflow and health. At that time, the main concept was all about indoor air quality (IAQ) and its parameters, with the impact of energy efficiency in the spotlight. However, two decades later, problems have arisen with sick building syndrome (SBS) and other building-related illnesses (BRI).

Thankfully, bad outcomes have rather quickly turned solutions and attitudes around. Since the 1980s, the focus changed and people started to realise that there was a need to connect the air with the environment and subsequently with health. Interest shifted from buildings being just energy-efficient, to being sustainable and providing a healthy environment – all at the same time.

This was the moment when IEQ became a broader subject, connecting indoor quality (air, thermal comfort, lighting and visual comfort with acoustical conditions) with the environment in buildings and health/well-being/productivity of all people indoors.

So now you know that IEQ is more complex than IAQ.

Remember this

IAQ is a subset of IEQ but plays a huge part in promoting the quality indoor environment and building experience. The difference between IEQ and IAQ can be subtle, but understanding the overlap of both concepts is important to creating healthier and safer indoor environments. 

IEQ benefits: good ventilation leads to healthy buildings

Peoples health and well-being in healthy buildings

The IEQ manifest puts peoples health and well-being at the centre of the EU built environment and focuses on the renovation of the existing EU building stock.

The IEQ manifest contains 8 recommendations in healthy buildings with regards to lighting, ventilation, heating and cooling, sanitary and operation, automation and control. Each recommendation comes with additional information with specifications and added value to improve IEQ (Indoor Environmental Quality). And here are some great points about IEQ benefits for everyone to consider.

Download the IEQ manifest

The IEQ manifest with recommendations is now available and can be accessed via the Eurovent website.

From the IEQ manifest


Potentially, lighting can account for around 20% of the total cost-effective energy-saving potential in non-residential buildings towards 2030.

The benefits of good light – natural and non-natural – are visual (good visibility, visual comfort, safety, orientation), biological (alertness, concentration, cognitive performance, stable sleep-wake cycle) and emotional (improved mood, energise, relaxation, impulse control).

LED light source brought a revolution in the lighting industry and LED can make the indoor environment more attractive, functional, dynamically adaptable to the specific needs and ensure increase energy efficiency.


“A badly ventilated building is an ill building, and this will inevitably lead to ill occupants. Therefore, ensuring the implementation of well-functioning ventilation systems in new and renovated buildings, to help guarantee an adequate IAQ, is also a critical step to optimise the energy consumption of buildings.”

Ventilation ensures that the buildings are energy-efficient and preserve the health of people living in increasingly insulated and air-tight environments.

Ventilation systems should deliver the indoor air quality – at least – based on the minimum regulatory requirements, and mandatory inspections and HVAC systems should ensure the HVAC optimal performance.

“The HVAC sector is responsible for almost half of Europe’s final energy consumption, out of which around 80% are still based on fossil fuels, especially in heating.”

Hygiene, automation, and control

Installers need to focus on IEQ benefits such as hygienic requirements guaranteeing the quality of water (including sanitary and plumbing systems), thermal comfort in environments (including heating, cooling and air conditioning) and controlled air exchange (with good air quality for occupants).

Other IEQ benefits are also planning and design, good training and certifications, and regular maintenance of the building services.

Benefits of building automation and control could deliver a safe and healthy environment, including individual space control, increased productivity and well-controlled indoor spaces.

Some of the important automation functions are IAQ automatic adjustments based on occupancy, demand-controlled ventilation and the possibility of self-controlled and self-learning system.

Indoor environmental quality (IEQ) is a perceived indoor experience of the building indoor environment that includes aspects of design, analysis, and operation of energy efficient, healthy, and comfortable buildings. Fields of specialization include architecture, HVAC design, thermal comfort, indoor air quality (IAQ), lighting, acoustics, and control systems.