Circadian rhythm and solar home design
If our body is not tuned to our circadian rhythm, we can hardly be in flow with Life.
Hello, fellow circadian organism!
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The Circadian Rhythm
My journey as a solar passive architect began without the understanding of the concepts I will lay out in this piece. 9 years ago when I first came in contact with the solar passive concept, I thought of it as a simple, mechanistic way to harness solar heat in our homes to reduce winter energy consumption and increase indoor temperatures and improve air quality.
It turns out, the presence of the sun in our lives is much more important. Humans developed in nature in the last 200.000 years, under the open sky as any other earthly being. It is only in the last 10.000 or so years that we settled down and started building shelters and shrines etc. Even more importantly, only roughly in the last 75-100 years did we become “indoor” creatures due to industrialisation and modern living.
To try to comprehend the scope of sunlight loss, consider the following: The sun shines with 120.000 lux. A typical urban living room lets in at most 1.000 lux at the window sill. Even under a heavily clouded sky, at 15.000 lux we get more scattered sunshine than in our living room.
Another: For every 2 hours spent indoors daily without sunlight, over a 50 year period, we lose out of 4.1 years of sunshine. While we spent 10-16 hours of our days outside a mere 300 years ago, how many do we spend today?
But why does this matter, you ask?
Why is our circadian rhythm important?
However powerful we’ve become, our lives still revolve around the sun every day. If our body is not tuned to the circadian rhythm we can hardly be in flow with Life.
In my field of architecture this is the the biological argument for solar design.
First we have to define what time is and redefine how we think about it.
Natural time & the nature of mechanical time
The Time that we are used to was invented only 3500 years ago in our 200.000 year history and has been broadly used from the end of the middle ages. Mechanical clocks became common in the 19th century.
This Time concept divided time into short term, rigid units: second-minute-hour-day-week-month-year. This lead to the ubiquitous linear and mechanical measurement of time and to the rhythm of life we are used to today.
In contrast to this, nature’s time can be perceived in a completely different way, the commonalities being the day - Earth’s complete rotation around its axis, and the year - Earth’s complete trip around the Sun.
Time can be considered cyclical over multiple scales and rhythmic - daily and yearly.
Over time we experience a spectrum of light colour: Early sunrise greets us at 2700K and quickly gets to 4000K cool that is called neutral white. At noon it shines at 5-6000K, and at sunset it warms down again to 2000K. These shifts provide our body with multiple inputs every day so it can function properly. Studies showed that blind people struggle to sync their bodily proving that the body cannot adjust itself on its own, without receiving the physical inputs through our eyes.
More importantly, this is only the visible spectrum of light. Any kind of artificial light we use, even if tuned to these numbers, it cannot reproduce the full spectrum of sunlight.
Over the whole year, the amount of daily sunlight provides a spectrum of temperatures which easily translates to seasonal energy - Winter - hibernation, Spring - rebirth, Summer - Abundance, Autumn - Wind down.
The whole set of changes play over the minimum period of a year, which nudges us to think long term, not short term.
We evolved under all these subtle daily rhythms and mechanical timekeeping with the modern concept of Time increasingly disconnected us from this grounded reality.
The human circadian clock
Now this is not my area of expertise, so I will be very brief about it. My goal is to show practical home design & lifestyle advice that improves our circadian rhythm. At the end of this issue you will find books and resources I read and recommend on this matter.
Simply put: We have to be directly exposed sun as much as we can, ideally both at the sunrise and at the sunset of the day.
This is how an ideal circadian day looks like:
Abundant sunlight on our body leads to a healthy circadian clock that is in tune with the environment:
Provides better, deep sleep.
Wakes you up naturally, without an alarm clock.
Makes your body and mind more energetic and creative.
Increases lifespan and third-age health.
It increases natural Vitamin D3 production.
Lowers odds of depression, greater odds of better mood.
Regulates cortisol, blood pressure and body temperature.
Synchronises the multiple organ clocks we have in our body.
Boosts testosterone.
If you still don’t think this is important, just think about how daylight savings time upsets your body for a couple weeks every time it is changed.
Designing homes around the circadian rhythm
I will tie this together now with solar passive home design. I read Dr. Satchin Panda’s The Circadian Code book in 2018 and it completely changed my stance towards solar design as it became so much more than just harnessing the sun’s heat for indoor comfort.
It is all about orienting rooms with different functions according to the circadian rhythm of the day.
First of all it is easier to design a multiple floor house than single floor one, because you can choose orientation freely for more rooms. Here’s a ground floor example I designed in 2020:
Bedrooms should be facing east, especially the master, so you can awaken with the sun. Children’s bedrooms we usually try to orient more towards south-east and south because children will spend more time in their rooms, especially as teenagers. At least one bathroom I try to place towards east too, so you’ll get sun while you get prepared.
Bedroom windows facing streetlights should be avoided at all costs. If it is not possible, some kind of shading solution should be employed in shutting out nighttime artificial lights.
Placing windows on two sides of a room improves daylight aperture dramatically. Not only you double the amount of potential daylight, the room will feel much bigger therefore much more pleasant to be in.
I try to place the kitchen to the north-east/north-vest to avoid overheating by overlapping direct sunlight and residual cooking heat. But it usually has one window to either east or west.
He recommended that Romans living in temperate climates make sure their winter dining rooms looked to the winter sunset, because when the setting sun faces us with all its splendor, it gives off heat and renders this area warmer in the evening.” But summer dining rooms should have a northern aspect. For while the other aspects, at the solstice, are rendered oppressive by the heat, the northern aspect, because it is turned away from the sun’s course, is always cool.”
- from John Perlin - Let it shine book.
As the above excerpt tells, indoor (winter) dining rooms should face south/south-west because that’s where the sun sets in the winter. Since the time of leisure usually comes after, living rooms would be placed towards the west.
Open spaces and rooms with multiple functions should have windows that capture light at different times and different angles, nudging us to play with tasteful window placement. It is better to have more windows on different walls and in different sizes than a large pane of glass placed on one wall.
A fantastic number of clients ask for reading nooks that are filled with sunlight:
These nooks are coveted because they double down on the indoor sunbathing effect we unconsciously desire in a world of dark, dimly lit and mouldy spaces. In some rooms, a 5-fold sunlight increase can be measured at the window sill compared to the darker corners. In older homes window sizes were not big but are usually well distributed on every facade.
All these considerations should be complemented with as many outdoor spaces, porches, terraces, archways as possible. These should mirror the orientations of interior spaces. For example I’d never place an outdoor kitchen to the south, but to east or west. Same goes for the outdoor living room. It should be in a shaded place that is cool in the summer and gets sunlight in the spring/autumn so its usefulness is expanded by being used for more than the summer season.
An existing home can be upgraded too, reshuffled internally so it better serves the inhabitants’ circadian life and health.
Practical advice for everyday circadian improvements
Before I wrap up, I will share all my strategies I employ as much as I can for keeping my circadian rhythm in sync.
I have been using the f.lux app on my computer for 6+ years to ease eye strain and help my circadian rhythm after sunset. f.lux winds down the blue light spectrum of the display, winding me down too. Mac users: f.lux is even better than Nightshift! Try it!
Staring into sunrise and sunset, 1 hour after rise, 1 hour before sunset resets the circadian rhythm. Added benefit - it improved my eyesight, for real.
Immediately throw out all lightbulbs over 2700K colour warmth!!!
Use LEDs with luminance and warmth variability or closest to candle/campfire light (1800K warmth bulbs)
After 8 PM use candlelight and warm reading lights only if possible.
Try to eat the last meal before sunset.
Exercise is best in the evening 5-7 PM, helps falling asleep, this has worked for me for many years now.
I drink chamomile tea before bed if I feel too awake.
I try to fast for at least 14 -16 hours everyday, so first meal is usually after 10 AM, after 7PM meal last night. Fasting also helps reset the circadian clock.
Conclusions
That’s it, I hope I helped you reconsider your relationship to the sun and through it, your home’s or future home’s design! Write me for design advice and improvements that better serves your circadian rhythm leading to better health!
I will leave you with this:
Next issue(s) will be about the 6.000+ year history of solar design & building.
Feel free to share your thoughts in the comments!
Until next time,
Solar
Circadian - related reading:
Dr. Satchin Panda - The Circadian Code
or the shortened The summary of the Circadian Code
David A.Sinclair - Why we age and why we don’t have to
A compelling video presentation I was inspired by by Ted Hunt.
Hello,
I just wanted to say that I recently found your Substack and have been really enjoying it. My wife and I have been looking at buying some land with family and this has provided plenty of food for thought.
We hope to build a passive solar home in southern Portugal in the next few years, so I’m soaking up as much information as I can on basic design principles: solar, aesthetic, architectural - thanks for sharing what informs your practice! (I too love Sarah Susankah’s books - she has made architectural principles accessible: “Home by Design” is my go-to as I think things through, with 6 chapters on light alone.) Walking around many of the monasteries in Portugal was highly instructive as well when it came to outdoor and in-between spaces - coming from Canada, it’s hard to imagine being able to use outdoor spaces year-round, but I’m really looking forward to it! I tend to think from the inside-out: what makes a room beautiful, comfortable, inviting, and functional? I will definitely incorporate these circadian ideas, some of which I hadn’t considered, particularly re Mediterranean climate outdoor living spaces.
What is your take on using ICF’s? Wood being more problematic due to both insects and forest fires in Portugal? Personally, I’d go with straw-bale SIPs or rammed earth (I too read Wrath of Gnon!) but we have to consider costs and labour availability, and the notorious bureaucracy… still researching!
Would love to see a list of your favourite books!