The element of time is essential to architecture. To create buildings, we should study how human activity changes during the day and during the year. These circadian and seasonal rhythms reflect inborn and environmental patterns. As architects, we can create harmony between these internal needs and external changes in space and architecture. Alvar Aalto phrased it perfectly, “We may define the ideal goals of architecture by saying that the purpose of a building is to act as an instrument that collects all the positive influences in nature for man’s benefit, while also sheltering him from all the unfavorable influences that appear in nature and the building’s specific environment”.

Looking back historically on architecture, there is a marked difference in the way spaces are used during each day and in each season. One room may be important in the morning and less so in the evening. A winter garden adds value in autumn, winter, and spring, while in summer people retreat into cooler temperatures further inside a building. In this way, a building provides a kind of inner rhythm following the outer ones, allowing a balance of daylight, temperatures, and humidity over time.

In the 1941 modernist manifesto, Sigfried Gideon wrote, “We are in the middle of restoring architecture to a more human scale.”  Eighty years later, I must emphasize that we are not there yet: Time is the fourth element in architecture, which can mean the difference between a bright, sunlit bedroom and a dark, gloomy bedroom in the morning, or access to, or denial of, sunlight in wintertime. As architects, we need to put as much effort into the geographical orientation of our structures as we put into height, width, and length. A building sits immovably on a plot of land, and is subject to the regional climate and conditions.

Architecture should take into account the morning sun, evening sun, summer sun, and winter sun.

Architecture can balance exposure to sunlight, as well as protection from it.  Daily and seasonal sunlight can be a planning tool and inspiration for solar architecture. Successful architecture can actually create an experience — or an illusion — of more light inside than outside.   At the latitude of cold, overcast countries such as Denmark  (56 °N), sunlight is a luxury.  I have developed a daily and seasonal planning tool as in the figure below  (from “Light, Architecture and Health – a Method” Carlo Volf 2013).

Circadian rhythm, seasonal, and daily sunlight tool.

This diagram illustrates a key message: On the inside, you see the schematic passage of the sun across the day at 56 °N latitude. The different black lines show sunrise and sunset at the summer solstice (longest day), the equinox, and winter solstice (shortest day). The blue circle follows some examples of physiological variables — for example, when body temperature is lowest, blood pressure is highest, and when light works to phase advance (PA) rhythms earlier or phase delay (PD) them later.

Of course, there are cultural differences in architecture. The Mies van der Rohe tradition of deep floor offices in glass buildings with open planning seems to be the rule in America, but can also be found elsewhere. This manner of optimizing daylight is not sustainable architecture. I think in the future architecture will develop a smaller footprint, fewer Euclidean shapes, thinner buildings, and be inspired by early European architecture where light was primary (for example, its “antibiotic” role at the time of Florence Nightingale and Niels Finsen). Or rather, to create a balance between light and darkness. That is what circadian rhythms teach us. We need to balance light and darkness, even though this is difficult when both the angle and the height of the sun change dramatically over the year.

One simple rule of planning solar architecture for human ecology is to make the most of the winter sun, which often leads to asymmetrical building design. A side effect of balancing sunlight is that it enables us to use ecologically renewable materials, such as wood, with little thermal mass but amazing qualities when it comes to indoor climate, light, air, humidity, and thermal performance.

“Architecture should defend man at his weakest” (Alvar Aalto)

Working with hospitals is fascinating. They are visible landmarks, reflecting current beliefs in society and medical developments.  I experienced myself the important effect of light when I was hospitalized, being very weak, and all my senses became heightened.  Light and shadows had great importance to me at that time. Sunlight and clear shadows may evoke large spaces, but modern hospitals are lit like moon bases, chasing the shadows away, using poor glazing on the windows and poor lighting fixtures.

Architectural experiences from the living lab, Eco Housing Mols                                        

I perform architectural experiments to test novel ideas about light, air, and natural surroundings at a full-scale lab called Eco Housing. Eco Housing represents an architectural example of simple solutions for putting nature back to work. It is based on a three-in-one solution: natural daylight (special glazing; window construction allowing UVB transmission), natural ventilation, and natural, sustainable materials. In nature we can find inspiration to create harmony between humans and technology, and create architecture that collects all the positive influences in nature for our benefit, while also sheltering us from all unfavorable environmental influences.


Eco Housing Mols, Denmark.  A living Lab for light, air, and natural surroundings. The architecture is based on self-ventilating wood construction and special glazing and window construction that transmits unfiltered, natural daylight, including UVB.

More by Carlo Volf

  • A film about “light, architecture and health” (“lys, arkitektur og sundhed”).  Short version from Aarhus School of Architecture on Vimeo.
  • A blog at the Daylight Academy reminding us that architects were once keenly aware of the health-supporting effects of daylight.
  • A Ph.D thesis, Light, Architecture and Health – a Method, from Aarhus School of Architecture, 2013.


Carlo Volf PhD, MAA is a Danish architect, works with daylight, ventilation, indoor climate and health on several architecture projects including hospitals, schools, elderly homes and social housing, and has won prizes for this work in daylighting, lighting and architectural planning. He is also CET’s Director for the Built Environment.