Materials and health: The seven sisters of indoor environment. Science.

Photo: Videndjurs Denmark. Troldtekt acoustics contributes to healing indoor environments.

Building materials and installations have a significant impact on health. In professional language, a distinction is made between indoor climate and indoor environment, where the latter concept, in addition to five physical aspects, encompasses the psychological and well-being factors in buildings.

This article offer scientific sources below.

Chris ButtersBy Chris Butters.

A well-known model is the seven sisters of indoor environment

  1. Thermal indoor environment
  2. Atmospheric indoor environment
  3. Acoustic indoor environment
  4. Actinic indoor environment
  5. Mechanical indoor environment
  6. Psychosocial indoor environment
  7. Aesthetic indoor environment

The surroundings, especially the indoor environment, in our buildings should contribute to maintaining good health for the healthy and stimulate healing for the sick.

Illustrasjon Kretsløphus. Gaia Lista.

Illustration: GAIA Lista

Many years of construction experience and discussions with researchers and specialists in indoor environment have convinced us of the importance, and neglect, of this topic. It requires highly specialized medical, chemical, and other expertise.

  1. Thermal indoor environment

This concerns the body’s thermal balance with the surroundings, i.e., temperature, humidity, drafts, clothing, and activity. The perception of room temperature differs depending on whether it is air temperature or temperature on surfaces – walls, floors, and ceilings.

People often set room temperature to 20 degrees, which is not necessarily the temperature of the floors and walls. We experience the temperature as higher if we have warmer walls and floors because we then receive radiant heat.

People have different perceptions of what is comfortable. Therefore, we work with adaptive comfort. Humans have great adaptability to variations in temperature and climate. By living with slightly lower indoor temperatures, we can reduce energy consumption and improve indoor environment and health.

This is an example of how health and energy considerations go hand in hand.

  1. Atmospheric indoor environment

This concerns air quality and pollution with particles, fibers, emissions, gases, allergens, toxins, and odors.

We also need air with suitable relative humidity – preferably between about 30-70%. Moisture in buildings and off-gassing from building materials, furniture, and fabrics are a much bigger problem for indoor air quality than the amount of carbon dioxide (CO2). CO2 actually shows little or no health effects up to very high concentrations above 5000 parts per million (ppm), but CO2 is very easy to measure and is therefore a frequently used indicator of how quickly the air is exchanged in a room.

Many say that we need large ventilation systems to remove moisture, radon gas, mold, and harmful emissions from building materials, furniture, and other items in our homes. But with the right designs, this can quite often be achieved with natural ventilation.

The best approach is to avoid using hazardous substances and build so that moisture problems do not occur. In other words: prevention, not expensive technological solutions like mechanical ventilation, humidifiers, and others.

  1. Acoustic indoor environment

This concerns sound perception, noise, vibrations, sound transmission, reverberation time, etc. Sounds are called noise if they are perceived as unpleasant.

Building regulations set limits for noise from indoor sources, neighboring apartments, road traffic, and other external noise sources. “White noise” is weak, steady noise that we eventually do not consciously register.

Tolerance for such weak noise is individual, but even though this is a new research area, an increasing amount of compelling research and conclusive findings confirm that exposure to noise, especially from sources such as traffic, can potentially affect the central nervous system.

We are getting less noisy ventilation systems, computers, and other equipment, but the question is whether we sometimes should have completely silent conditions, especially where we need to rest, like in the bedroom.

A good building should provide opportunities for silence and for controlling the indoor environment including the acoustic environment according to the users’ varying adaptability, needs, and desires.

  1. Actinic indoor environment

This concerns radiation, both visible (light) and invisible, including both ionizing (radioactive) and non-ionizing radiation. The latter is receiving increasing attention abroad, especially in German-speaking countries, but little in Norwegian professional circles.

Light, both daylight and artificial lighting, is recognized as very important for both physical health and well-being. The less known and more controversial topic is radiation. It is generally agreed that this radiation is associated with health risks, but there is considerable disagreement about how strong such radiation must be before it poses a health risk – and also about what problems can arise.

Radioactive radiation from radon in the ground is a well-known issue and not difficult to prevent. It has been established and agreed upon, among other things by Swedish research, that radiation from mobile phones can be hazardous to health.

Electrohypersensitivity or electromagnetic hypersensitivity is occurring more frequently, and researchers demand it to be recognized as a neurological disease in Sweden. GAIA’s stance as architects is that we should take this issue seriously – and that, in fact, without major additional costs, we can design buildings where these risks are minimised.

The World Health Organization (WHO) announced as early as 2011 that high-frequency radiation can cause brain cancer. The Council of Europe adopted a resolution stating that the precautionary principle must be respected and limits set for electromagnetic fields must be revised.

There are increasingly more electronic control systems in our buildings, with wireless sensors and other equipment with their advantages but also consequences in the form of ever-increasing radiation, both in strength and in the number of frequencies we are exposed to. This is a large and complex topic which is discussed in more detail in the bibliography at the bottom of the article with scientific references.

  1. Mechanical indoor environment

This includes functional design and fittings: Ergonomics, adaptation to users and risks, dimensioning, reach, sitting positions, protection against injuries (e.g., slipping on smooth floor coverings, unsafe stairs and railings), etc.

  1. Psychosocial indoor environment

This pertains to interpersonal relationships: Relationships between colleagues in the workplace, adaptation of tasks, family relationships at home, unsafe public spaces, etc.

Discomfort can take the form of alienation, anxiety, stress, and other factors which in turn can lead to both psychological and physical ailments.

Research shows that poor psychosocial work environment can lead to serious health and social consequences.

  1. Aesthetic indoor environment

This is a broad topic that includes everything that affects our senses – sight, hearing, taste, smell, etc. –significant factors in well-being.

Many philosophers have pointed out to what extent the modern world is a world where sight predominates. Not least because it is associated with reading and thus with the intellectl – as opposed to the concrete world, where smell, hearing, taste, and touch are important. Thus, we also see a tendency among architects and designers to cultivate aesthetics mostly in a visual sense. This quickly turns into intellectualization of the mind as opposed to the concrete – ecological – world and life experience.

Harmony, colors, spatial forms, materials, and symbolism play a role. But also touch, smell, and our other senses provide important aesthetic experiences. For example, some materials are perceived as “warm” and others as “cold”. Physical feeling and well-being are influenced by the consistency and structure of surfaces.

Natural materials provide a warmer and softer experience than many industrial materials.

Health and Risk

We humans react differently to the many different allergens and influences in our indoor environment. Different countries have very different legislation and practices on how to deal with these.

The precautionary approach must be our approach. Universal design requires that buildings and environments should be designed in such a way that they are good for everyone, including people with various types of disabilities.

We have come a long way with respect to physical accessibility for people with mobility impairments; and partly in terms of adaptation for visual and hearing impairments. But our built environment should also be healthy for allergy sufferers, those with respiratory problems, and those who are electro-sensitive.

Therefore, to the greatest extent possible, we must prohibit building materials, installations, and solutions that can cause discomfort and diseases, allergies, and asthma. This is not addressed in regulations on universal design – even though these groups are included in the definition.

Both human adaptive abilities, buildings’ resilience over time, indoor environment and health in general, and the more controversial topics such as radiation, require much more attention and research in the future.

Also read: How Troldtekt Acousticpanles contributes to healing architecture. Ad.


Hidden harms of indoor air pollution — five steps to expose them (

Direct human health risks of increased atmospheric carbon dioxide | Nature Sustainability

Effects of nature sounds on the attention and physiological and psychological relaxation – ScienceDirect

Radiation-induced tumor immune microenvironments and potential targets for combination therapy | Signal Transduction and Targeted Therapy (

Why electrohypersensitivity and related symptoms are caused by non-ionizing man-made electromagnetic fields: An overview and medical assessment – ScienceDirect

Quantifying the Impact of Scenic Environments on Health | Scientific Reports (

(PDF) Psychosocial interventions at the workplace, a systematic literature review (

In Norwegian and Swedish: