Natural Daylighting in Design

As we move deeper into the fall season the shorter days are more noticeable. With shorter days comes less daylight and with less daylight comes the potential for our energy levels to change. Our body is physiologically in tune with the natural cycles of the sun and night, which synchronizes our circadian rhythm with signals from the sunrise and sunset. In the morning, exposure to the sunrise or natural daylight helps activate our hormone production of serotonin. In the evening, exposure to darkness helps stimulate the production of melatonin. Cortisol also plays a role with our circadian rhythm by peaking just before the body wakes up and guiding some of our initial waking energy and hunger levels.

Melatonin helps our body rest and sleep well. Serotonin effectively gets converted to melatonin once we begin to experience a lack of daylight, so our body needs exposure to natural daylight first in order to have reserves of serotonin available to aid the nighttime sleep. The combination of the wake and sleep with the serotonin and melatonin cycles form our body’s circadian rhythm. We can shift our circadian rhythm in one direction or another based on our timing of daylight and darkness exposure. Your health is highly dependent on regular sleep patterns, so preparing your environment and daily rituals with regular daylight exposure is beneficial to your well-being.

Natural daylight that we experience from the sun, or even on an overcast day, provides a full spectrum of light. This means that within the visible range of the electromagnetic spectrum, we are receiving a decent spread of all colors of light at high luminance (lux) values. It is challenging to obtain the full spectrum of daylight from artificial lights, with exception of specific light-boxes designed to emulate sunlight and intended for light therapy purposes with limited exposure times. If we are unable to spend any time outdoors on a given day, we may find limited means to have natural daylight play a role in aiding our circadian rhythm. However, we can design our homes with appropriate windows, fenestration, and natural daylighting strategies to optimize exposure to sunlight when it is most needed.

One great example that I love is the way that entrances to traditional Navajo dwellings are designed to face east to welcome the morning sun when one is leaving their home at the beginning of each day. Stepping outside first thing in the morning is optimal if your space and temperatures allow for this. I have an east-facing outdoor deck that is ideal to sit on with my morning coffee or tea. It is truly great to receive direct sunlight in the morning, if possible, which can be accomplished indoors as well. As long as you are not in a hot climate during seasons when heat gain is a concern, incorporating east-facing windows for direct morning sunlight is one of the best strategies for starting your day. Setting up a ritual for sitting near the east-facing windows each morning for 20-30 minutes will provide a decent amount of daylight to kick-off your serotonin production for the day.

Indirect daylight, or light that is first reflected off of other surfaces before reaching your space, is also beneficial. If you don’t have east-facing windows in your house, perhaps you have opportunity for adding a skylight on the east side of your roof or light-shelves that can bounce light into your space from other directions. Indirect daylight is not as intense as direct daylight, but as long as it is originating with the sun it will still provide a full-spectrum range of light. It is wonderful to have consistent daylight in our building interiors as this also helps reduce our dependency on electric lighting and keeps our utility bills a bit lower.

Finally, diffuse light is also beneficial even though it will be the most diluted or lowest intensity daylight source. Diffuse daylight occurs on overcast or cloudy days when the atmosphere refracts and bounces light around in so many directions that it becomes filtered and subdued. We can still get a full spectrum of daylight from diffuse light; it will just be the less intense. If you frequently experience overcast days in your climate location, you may want to spend even more time with daylight exposure in the morning. If you only have north-facing windows in your house, you will be receiving diffuse daylight from the northern part of the sky (assuming your location is in the northern hemisphere). Sitting in diffuse daylight for 45 minutes in the morning will benefit your circadian rhythm for the day.

I am currently living in a northern climate, and although my space has adequate windows with east orientation for direct morning sun, many days are overcast and cloudy. Because of this and my own physiology with tendencies of seasonal affective disorder, where lack of daylight can cause low energy and depression, I purchased a light therapy box. I have not started using it yet as it just arrived last week! However, I am prepared to make use of the light box throughout the winter months as part of my morning wake-up routine. Sitting near the light box for 20-30 minutes each morning while writing in my daily planner or reading news should provide the boost needed to kick-off my serotonin production for the day.

It is also important to maintain natural daylight exposure throughout the entire day. Unfortunately, many office buildings, and some homes, have deep floor plates with interior spaces that do not receive any natural daylight. If you inhabit spaces that have little to no daylight throughout the day, it is important to take frequent breaks and occupy a space near a window or step outside for some sun exposure. This helps your body maintain the cycle of daylight exposure up until evening for your internal clock to keep its circadian rhythm on track. Ideally, we would want consistent daylight exposure throughout the entire day, so integrating windows, skylights or other natural daylighting strategies into your home or office space is best. Optimizing windows and skylights for natural daylight while also optimizing for the climate conditions to control or facilitate heat gain requires a careful study of the local sun angles, temperatures, and sky conditions (cloud cover vs. clear sky ratios). Consult with an architect or reference materials to determine the optimal orientation and placement of fenestration within the exterior envelope of the building.  

If you are interested in more information about designing or renovating your house to optimize the natural daylighting, reach out to AIDA, LLC today for a consultation.You can always find more information and healthy home resources at Aletheia Ida Design and Architecture, LLC (AIDA, LLC) at www.aletheiaida.com.