Sunlight has two spectra – the visible spectrum and the invisible spectrum.

VISIBLE SPECTRUM – The visible spectrum consists of white light which is a combination of seven main colours called VIBGYOR’ which stands for the colours, Violet, Indigo, Blue, Green, Yellow, Orange and Red. These Colours, depending on the colour and intensity have deep psychological effects on a person’s moods and hence have to be used sensibly for creating a good, positive environment. The effect of colours has beeen explained under  Vastu Colours of a House.


INVISIBLE SPECTRUM – The invisible spectrum flanks the visible spectrum on either side and consists of the Ultra Violet (Chemical) Spectrum and the Infra Red (Thermal Heat) Spectrum. The Ultra-Violet (UV) rays have a shorter wavelength than the visible light rays and are invisible. They kill bacteria and aid in the synthesis of Vitamin D in our bodies. The Infra Red rays have a longer wavelength than the visible light rays and are also invisible. They are the cause for the heat of the sunlight.

Vastu Shastra has a scientific basis.  It is therefore, worthwhile to understand the importance of these Vastu factors, their positive and negative effects on Man and how the positive effects can be used to advantage in the design of his dwelling. All this has been explained under the following headings.

Why is the Sun considered a life giving orb?
How is sunlight beneficial to humans?
What is the best time to expose to the Sun?
Why is the Sun an important Vastu factor?
How does Vastu Shastra ensure that the inmates benefit from the useful effects of the Sun?
How does the Vastu Mandala ensure that the inmates benefit from the useful effects of the Sun?



The Sun illuminates the Earth and it sustains life. It is for these reasons that Indians, from time immemorial, worship the Sun God also known as Surya.

Sustain life – Plants make glucose (energy rich food) from Carbon dioxide of the air and water in the presence of sunlight and release oxygen as a by-product into the air. This process called Photosynthesis, is absolutely necessary to sustain life on Earth, because all living things get a continuous supply of oxygen and animals get food (Carbohydrates) from the plants.

Illuminates the Earth – The white bright light of the Sun illuminates the Earth and is the reason we are able to see. Even the colours we see all around is because of the Sunlight since it contains all the possible colour variations. When sunlight falls on a coloured object, it reflects the light of the object’s color into our eyes while all the other colours of the light are absorbed into that object, giving us the perception of colour. Thus, an apple appears red because it reflects red light.




  • Endorphins: Sunlight increases the amount of endorphins in our blood which creates a feeling of well being in us and reduces the incidence of depressive conditions like SAD. (Seasonal Affective Disorder (SAD) is a kind of winter depression that affects lots of people during winter due to shortening of daylight hours.
  • Weight loss: Sunlight reduces weight caused by water retention.
  • Lowers Blood Pressure (BP): Sunlight lowers blood pressure.
  • Good for the immune system: Sunlight strengthens the immune system.
  • Positive effect on cholesterol: Sunlight increases the good cholesterol and lowers the bad.
  • Normalises blood sugar:  Sunlight increases low blood sugar and lowers high blood sugar.
  • Good for the Liver: Sunlight helps detoxify the liver. Doctors recommend exposing jaundiced new-born babies to the morning sunlight.
  • Increases endurance: Sunlight increases muscle tone and endurance.
  • Good for healing: Sunlight speeds up healing of unwell people. Elderly people and people who have been unwell for a long time, feel a lot better after sitting out in the sun.
  • Kills germs: The UV rays of the sunlight kill germs.
  • Increases alertness: Sunlight boosts serotonin levels which help a body to stay alert.

Regardless of the season, it is important for our bodies to get at least 15 to 20 minutes of natural sunlight every single day, to provide us with positive health benefits. However, we need to protect ourselves from over-exposure for long periods of time as it can be harmful.



It is best to expose to the Sun when it is not too hot to cause sunburn and other harmful effects. The intensity of the sunlight and heat is related to the height of the sun in the sky and the pathway of the beam of sunlight through the atmosphere. At mid-day the sun is almost directly overhead and therefore, the pathway of sunlight is half the length compared to the pathway in the morning or evening. Hence the intensity is maximum at noon and least in the morning or evening.

However it feels hotter in the evenings as compared to the mornings, because the ground reflects and re-reflects the heat waves back into the air. Whereas, in the morning, since the sunlight just starts to heat up the cold Earth after a dark night, it feels a lot more pleasant. Also, since the morning air is thick with carbon dioxide (exhaled by living things through the night), it filters out most of the UV radiation allowing only a small amount which is not harmful to us.

Hence it is most comfortable and beneficial to expose ourselves to the morning sunlight – when it is not too hot – for at least 15 to 20 minutes a day.

sunlight streaming into the house is positive energy



Scientifically, it has been proven that the Sun is very important and essential to humans in their day to day life and surprisingly, the Vastu pundits knew this fact, so many thousands of years ago. Therefore, the Sun’ became an important Vastu factor and was taken into account in the design of buildings. Vastu Shastra takes into consideration the the changing intensity of the sunlight from place to place, sunrise to sunset and from season to season in the design of buildings as explained here:

Constant light from the North direction: In India, since it is in the northern hemisphere close to the equator, there is constant light from the North side most of the year.
Morning light from the East direction: When the Sun rises in the East in the morning, the intensity of the light is much less and so this is the right time to expose. Also, the UV rays of the morning sunlight can destroy the germs that would have multiplied during the night.
Infra-Red heat in the West and South direction: When the Sun sets in the West in the evening, the intensity of the sunlight is reduced. However, the Infra Red heat rays of the Sun are projected to the South and West sides. And since the infra-red rays get reflected and re-reflected by the ground, the West side and the South side are much hotter in the evenings and even at night.



The main aim of Vastu Shastra in designing a house, is to ensure that the inmates of a house are inadvertently exposed to the useful rays of sunlight while performing their activities, even if they are inside the house the whole day. But during a day, people perform different activities in different rooms at different times and the Sun’s position keeps changing from sunrise to sunset. So to ensure that the inmates get exposed to sunlight constantly, each room is positioned so that it faces the Sun at the time of the day when it is most likely to be used by them. This has been prescribed in an ideal plan called the “Vastu Purusha Mandala”.

The big windows of the house ensure that the inmates get ample sunlight



The Vastu Mandala is a square, metaphysical plan of a house which shows the position of the rooms of a house. In the Vastu Mandala, the rooms have been positioned in specific directions, keeping the beneficial effects of the Sun in mind. They are explained here:

Water source, wells: The water source, wells are preferred on the East and North sides of the house so that the UV rays of the morning sunlight can kill the germs and purify the water before you start using it.

Kitchen: It is advisable to have the kitchen platform on the Eastern side so that the morning sunrays will destroy the germs on the kitchen counter and prevent the food from spoiling. Moreover, the person who is cooking is inadvertently exposed to the useful, morning sunlight. (In the olden days, women stayed at home and never stepped out, and so this was a way for them to get exposed to the beneficial sun rays).

Windows: There should be fewer windows on the South and West side, and the walls should be thicker to reduce the heat. However there should be more windows in the North and East to allow constant sunlight into the House.

Toilets, Store rooms: Lesser used rooms like the toilets, store rooms etc should preferrably be on the West side as they tend to get hotter. Moreover they serve as buffers and prevent the rest of the house from getting heated up. And the heat keeps these rooms dry and free from moisture, germs, fungus etc.

Obstacles: There should be no obstacles, tall trees, high compound walls on the North and East sides of the house, so that the constant sunlight from the North and the morning sunlight from the East, can engulf the house, brighten it and kill the germs and bacteria that would have multiplied during the night.

Balconies, Terraces, open spaces: More  Balconies, terraces and open spaces are desirable in the East and North sides again for the same reason as above.

Sunlight in the balcony

Trees: It is advisable to have tall trees on the South and West sides, to protect the house from the direct sunlight and also to give pure oxygenated air to the inmates (since trees and plants produce oxygen during the process of photosynthesis).
This post is about the Vastu Shastra Factor, the effects of the Sun on living things. Read about another Vastu Shastra Factor that affects us and the design of our buildings, namely:

Related Topics:

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6 thoughts on “SCIENTIFIC VASTU FACTOR | SUN’S EFFECTS | An Architect Explains

  • February 7, 2009 at 9:14 pm

    It is a wonderful site and has very good reasoning and explaination for each topic.
    It is a pleasure to read a clear and knowledgable article.
    Hi Abhinaw,
    Thank you for your appreciation. Please share in your circle.

  • May 13, 2010 at 6:30 pm

    Really like this article, also is there any additional benefit from the point of sunrise to half hour.
    Thank you Dinesh,
    The moment the Sun rises, the world awakens because it revives living things. So exposure at this time is very beneficial and may dictate your mood through the day. It is no wonder that Surya was and is worshipped by many cultures.

  • February 26, 2015 at 12:14 am

    its a really helpful article, can i have few specific principles of Vastu Shastra related to sun and their scientific logic or reasoning.
    Basically i want to show a link between Vastu Shastra and climatology…
    Hi Satvik,
    I will soon put up a post to show a link between climatology and vastu Shastra.

  • June 14, 2015 at 5:48 am

    I live in India and have my house windows facing south, I would like to correct you that because India is in northern hemisphere and earth being tilted around 23 degrees, in summer there is no sunlight from south side and in winters I get full sunlight in my house from side.

    In India, north windows do not get any light any time of year, because in summer 23 degrees closer to sun still being on curvature of earth, sun is almost directly up hence no direct light, while in winter being 23 degrees away from sun and being on curvature of earth, light comes from south.
    Hi Vinay,
    I agree with you that in winter, the sun is more towards the South side. But in summer which is longer than winter, it is in the North. Just watch the sun’s rays early morning now in june. It comes more from the North side. Windows in the North is preferable to windows in the south side for this reason. Moreover, the sun is more in the south in the afternoons when it is very hot, irrespective of the season. so the south side gets heated up more than the North side. That is why windows are not preferred in the south side.

  • December 24, 2015 at 7:05 am

    I have a small question about the constant light from north. How is that possible in India? India is in northern hemisphere and hence the sun will be in the south eastern direction most of the year, remember the “ayana”. Hence, I think the southern region of the house is illuminated more.
    Please correct if I am wrong.
    Hi Shibu Kumar,
    Since the tropic of cancer runs through Madhya Pradesh in India, the sun apparently moves till there during summer and then moves southwards during winter. But this does not cause mush of a change in the amount of sunlight, south of the tropic of cancer, since the sun is more or less overhead for most of the year except for a short period in December. So most of India gets ample sunlight throughout the year and only the northern-most parts get less sunlight during winter.
    You are right in saying that because of this, there is more sunlight from the South but you have to remember that this is harsh light and not what we want in the house. On the other hand the light from the North is less harsh and more or less constant for most part of the year. So we want to take advantage of this in the design of our buildings.

  • October 27, 2016 at 2:49 am

    This is exactly the logic I was looking to read about. I have believed in Vasthu almost forever now, but I do feel somethings need to change with time.
    As you said “people perform different activities in different rooms at different times and the Sun’s position keeps changing from sunrise to sunset. So to ensure that the inmates get exposed to sunlight constantly, each room is positioned so that it faces the Sun at the time of the day when it is most likely to be used by them.”
    Today our social behavior and habits are quite different from the olden days. Women no more spend so much time in the kitchen. And bedrooms which were earlier only used from night to sunrise, are now as much used in the day time too. I have my bedroom in the SW, as per Vasthu. but I always envy the light in my son’s bedroom that’s in the SE because it gets the best light in our entire house, whether in winter or in summer! I therefore prefer the SE direction for most bedrooms of today. Do you justify having the bedroom in SW?
    Hi Anjali,
    First of all, I am glad that you can relate to what I am trying to convey. I do not know where you live – depending on the geographical location, the sun position can vary a bit. In bangalore I have observed that in the mornings, the SE gets a lot of light but by 11 am, it shifts to the SW part and remains bright till around 4 pm. So both corners are good for bedrooms.

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