A Guide to Generating Vitamin D at Home
By Holistic Interior Architect, Laura Wencker
Year & Daytime Windows for Vitamin D
-
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid-May – End of August—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: UVB not present
Summer Solstice: 8.40 – 17.35 (8h 55 min)
Fall Equinox: UVB not present -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Beginning of April – Beginning of September—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: UVB not present
Summer Solstice: 8.55 – 18.05 (9h 10 min)
Fall Equinox: UVB not present -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of March – End of September—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 11.30 – 13.15 (1h 45 min)
Summer Solstice: 8.40 – 18.00 (9h 20 min)
Fall Equinox: UVB not present -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of March – End of September—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.45 – 13.00 (2h 15 min)
Summer Solstice: 8.10 – 17.30 (9h 20 min)
Fall Equinox: UVB not present -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of March – End of September—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.45 – 12.00 (1h 15 min)
Summer Solstice: 8.40 – 18.05 (9h 25 min)
Fall Equinox: UVB not present -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of March – End of September—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.45 – 13.15 (3h 30 min)
Summer Solstice: 8.45 – 18.05 (9h 20 min)
Fall Equinox: 10.50 – 13.45 (2h 15 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of March – Beginning of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.15 – 14.15 (4h 00 min)
Summer Solstice: 8.30 – 17.55 (9h 25 min)
Fall Equinox: 11.20 – 14.45 (3h 25 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Beginning of March – Beginning of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 11.00 – 16.00 (5h 00 min)
Summer Solstice: 8.45 – 18.10 (9h 25 min)
Fall Equinox: 12.00 – 16.30 (4h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Beginning of March – Beginning of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.45 – 14.30 (4h 45 min)
Summer Solstice: 8.25 – 17.50 (9h 25 min)
Fall Equinox: 10.45 – 15.00 (4h 15 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Beginning of March – Beginning of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.15 – 15.15 (5h 00 min)
Summer Solstice: 9.00 – 18.25 (9h 25 min)
Fall Equinox: 11.15 – 15.45 (4h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Beginning of March – Mid of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.15 – 14.00 (4h 45 min)
Summer Solstice: 7.55 – 17.20 (9h 25 min)
Fall Equinox: 10.00 – 12.45 (2h 45 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of February – Beginning of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.30 – 15.30 (5h 00 min)
Summer Solstice: 8.20 – 17.45 (9h 25 min)
Fall Equinox: 11.30 – 16.00 (4h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of February – Mid of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.00 – 15.30 (5h 30 min)
Summer Solstice: 9.00 – 18.25 (9h 25 min)
Fall Equinox: 11.00 – 16.00 (5h 00 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of February – Mid of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.00 – 16.00 (6h 00 min)
Summer Solstice: 9.10 – 18.35 (9h 25 min)
Fall Equinox: 11.00 – 16.30 (5h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of February – Mid of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 8.30 – 13.45 (5h 15 min)
Summer Solstice: 8.15 – 17.40 (9h 25 min)
Fall Equinox: 9.20 – 14.20 (5h 00 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of February – End of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.00 – 15.00 (6h 00 min)
Summer Solstice: 8.15 – 17.40 (9h 25 min)
Fall Equinox: 10.00 – 15.30 (5h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of February – End of October—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.30 – 15.30 (6h 00 min)
Summer Solstice: 8.45 – 18.10 (9h 25 min)
Fall Equinox: 10.30 – 16.00 (5h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of January – Mid of November—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.00 – 15.30 (6h 30 min)
Summer Solstice: 8.30 – 17.50 (9h 20 min)
Fall Equinox: 9.50 – 16.10 (6h 20 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of January – Mid of November—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.30 – 16.15 (6h 45 min)
Summer Solstice: 9.15 – 18.30 (9h 15 min)
Fall Equinox: 10.30 – 17.00 (6h 30 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
End of January – Mid of November—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.55 – 16.25 (6h 30 min)
Summer Solstice: 8.25 – 17.40 (9h 15 min)
Fall Equinox: 8.45 – 15.00 (6h 15 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of January – End of November—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 10.15 – 17.00 (6h 45 min)
Summer Solstice: 9.00 – 18.15 (9h 15 min)
Fall Equinox: 11.00 – 17.45 (6h 45 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
Mid of January – End of November—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 9.10 – 15.55 (6h 45 min)
Summer Solstice: 8.45 – 18.00 (9h 15 min)
Fall Equinox: 9.00 – 15.40 (6h 40 min) -
TIME OF YEAR
Approximate period of UVB availability for vitamin D production
All year long—
TIME OF DAY
Approximate daily UVB window for vitamin D production
Spring Equinox: 8.25 – 15.25 (7h 00 min)
Summer Solstice: 8.10 – 17.25 (9h 15 min)
Fall Equinox: 8.00 – 15.00 (7h 00 min)
Generating Vitamin D at Home
1. Observe where and when direct sunlight enters your home.
For vitamin D production, exposure generally needs to take place when UVB is available — typically around the middle of the day, depending on the season, latitude and atmospheric conditions.
2. Set up the space
Sometimes, you need to make a few adjustments. Place a rug, a daybed or a bed, or move the couch so you have a comfortable place to sit or lie down and soak up the sun.
3. Open the window
This is crucial.
UVB does not pass effectively through ordinary window glass, so sitting in direct sunlight behind a closed window does not provide the same opportunity for vitamin D production.
When you want to sunbathe, open the window and let your skin receive the sunlight directly.
4. Let your skin receive the light
When appropriate, allow some skin to be directly exposed to the sun.
Clothing and sunscreen reduce the amount of UVB reaching the skin, so some direct skin exposure is necessary for vitamin D production.
A note of care
These timeframes are intended as practical reference points, not as medical advice.
There are many factors that influence vitamin D production, including latitude, season, weather, skin type, age, clothing, sunscreen use, individual sensitivity and previous sun exposure.
So rather than treating these timeframes as a prescription, use them as a way to understand when UVB may be available in your location.
And most importantly, listen to your skin. Step out of direct sunlight as soon as your skin starts to feel hot, irritated or reactive, and never aim for sunburn.
I encourage you to use this guide as a starting point, do your own research, and take responsibility for how you choose to apply this information to your own body and circumstances.
Go furtherFor even more precise data based on your location and skin type—and to calculate how much vitamin D you may produce each day—download the Dminder app on your phone.
About
I’m Laura — an architect, creative consultant and holistic interior architect exploring the relationship between our homes, our bodies and our everyday well-being.
My work brings together architecture, psychology of space, building biology and a more holistic understanding of the environments we live in.
Through my online courses and upcoming programs, I share practical ways to look at our homes differently — from light and materials to spatial organisation, sensory comfort and the subtle ways our surroundings can support us in everyday life.
This guide is just one small piece of a much larger exploration.