Light and Air Ventilation as per Vastu:

Vastu Purusha Mandla having 81 Padas is considered ideal for Residence purpose.   Vastu Purusha Mandala compromises 4 squares one inside other starting from:
1. Paischa Sthan (PS) (Outer Area blocks).
2. Manushya Sthana (MS)
3. Devta Sthana (DS)
4. Brahma Sthana. (BS) (Inner most)

The outer area of Vastu Purusha, known as Paisacha Sthan, and Inner most area, known as Brahma Sthan, are supposed to be construction free. Any construction in these two areas can disturb/ obstruct the air ventilation and Sun light entrance.

Further, open areas of BS and PS are governed by Space i.e. Akash Tatva (आकाश तत्व). Space itself is blank or open area...but it has its own importance among 5 Elements:
* Fire, Water, Air, Light and Space.

Space is necessary for the movement of the other 4 elements. Space is necessary for communication and movement. Air Flow by means of Space...not only allow comfortable breathing but also helpful to maintain freshness and temperature, both inside and outside. Same way, Light ( from Stars, Sun and Moon) have an easy entrance through open areas.

In a Vastu, a 3 dimensional structure**, Space is primarily limited by Height & Provision for open areas inside and outside of constructed area. Any abnormality between Height & Open Area can affect Space Element...which can further affect other Elements. Though, at primary level... Space directly affect Light and Air. Also, in higher building as much we go up, earth element becomes weaker and weaker. So, Height need a close attention both ....... inside the rooms as well total height.

Any disturbance with Space element can result in psychological issues.