Light is of enormous importance to all life. Throughout evolution, many organisms, including humans, have adapted to the rhythm of the sun. Sunlight has become an important regulator of bodily functions, such as hormone production and the regulation of the day–night rhythm.

Because of this, the human body reacts to the properties of artificial light sources to which we are exposed for much of the day in modern times.

Sunlight changes throughout the day, sending important signals to our bodies. If artificial lighting deviates too much from this natural pattern, it can negatively affect health and well-being. Building biology uses the sun as a model for lighting design, mimicking natural lighting conditions. This approach aligns with the guiding principle of building biology, „Nature is the ultimate standard.“

Several factors must be considered to achieve this, such as choosing the correct color temperature and brightness for each application, as well as the light’s spectral composition, potential flicker, and electromagnetic emissions.

The spectral composition of light primarily affects the sleep–wake cycle. An excessively high proportion of blue light in the evening, as is sometimes found in LED lights, can disrupt the natural process of feeling tired and make it difficult to fall asleep. This effect is referred to as the melanopic, or non-visual, effect.

Flicker does not occur in natural light and should be avoided in artificial lighting. Although flicker is often not consciously perceived, it can lead to fatigue, headaches, and difficulty concentrating.

Electromagnetic radiation, colloquially known as „electrosmog,“ can also occur with LED lights and is now under critical scrutiny.

Measurements

According to an EU study, LED lights are predicted to account for around 96% of the lighting market in the near future. Therefore, assessing them from a building biology perspective is becoming increasingly important. Although LED lights offer advantages such as high energy efficiency and longevity, questions remain about their long-term health effects in living and work environments.

My bachelor’s thesis at the Technical University of Rosenheim, developed in collaboration with the Institute of Building Biology + Sustainability IBN, addresses this issue.

The thesis aimed to take measurements using commercially available LED lights, compile the results into an LED Light Catalog, and make the catalog publicly available to consumers as a guide.

To draw sound conclusions about the LED lights under examination, we evaluated light quality, flicker behavior, and electromagnetic emissions. The catalog also includes energy efficiency and price information to increase its practical value and provide consumers with a complete picture.

Specifically, we examined 23 LED lights with GU10 and E27 bases from various manufacturers. We wanted to include a wide range of prices and quality levels in the selection to cover as much of the market as possible.

We defined the parameters of the aforementioned topics, designed the measurement procedures, and developed an evaluation matrix.

Results

The results are mixed. Some LED lights performed very well, including select models from BioLicht, Ledvance, and also IKEA.

Many of the tested models achieved excellent scores, particularly in the categories of light quality and flicker behavior. Some manufacturers offer models that can be controlled via remote or preprogramming to adjust dimming levels and light color, which makes it easier to mimic natural lighting conditions.

However, remote control options opened up a new area of investigation. We wondered if the radio frequency electromagnetic fields generated by these lamps‘ control systems could negatively affect the human body. All measurements in this area showed no abnormal values.

In contrast, the ELF electric fields exceeded the recommended building biology guideline values for all LED lights measured at a distance of 80 cm (32 in) or less. These guideline values apply to areas where people spend extended periods of time, so this finding is particularly relevant for bedside and desk lamps. At greater distances, the values drop rapidly. At 130 cm (52 in), the lamps‘ ELF electric fields are barely measurable.

Another finding: None of the energy-efficient LED models could simultaneously deliver good color quality or a high color rendering index. Thus, energy efficiency often comes at the expense of light quality – a problem that future developments should address.

The measurements also revealed no correlation between high price and good quality. There are affordable models with good properties that meet building biology requirements, as well as expensive models that failed to achieve good measurement results. Overall, it is clear that LED technology has the potential to meet building biology requirements and is an excellent choice for lighting design. However, the wide range of results shows that not all LED lights are suitable. Therefore, it is necessary to carefully consider all the facts before making a selection.

LED Light Catalog and bachelor’s thesis

The LED Light Catalogand the entire bachelor’s thesis are now available as free downloads on the IBN website. See the links below for more information.

The theoretical section of the thesis provides a detailed scientific analysis of the examined topics and parameters, as well as current research on potential health effects. The practical section, on the other hand, provides detailed information on the entire measurement procedure.

The LED Light Catalog provides an overview of the tested models and their measurement results, as well as an evaluation guide organized by topic.

This tool empowers consumers to educate themselves and make informed decisions about creating healthy, inviting living spaces.