Ventilation by means of solar chimney effect

Ventilation by means of solar chimney effect

Since it is ideal for a building to be slightly positively pressured, a pressure sensor detects any negative pressure such as would occur if the vents, windows or doors are closed. It then closes off the system to the building and instead switches to self-cooling mode sourcing air from outside instead of inside in order to cool down the solar ventilator.

The graph ‘Relationship between velocity and temperature to passively ventilate’ shows that as the temperature rises and falls throughout the day, the velocity of air flowing out of an opening of the solar ventilator with cross sectional area 0.1 m2 also increased and fell. On this day the ambient temperature reached about 25C. The heat from the solar ventilator passively exhausting reached over 60C. It is expected that the temperature and rate of thermal siphoning will increase further as ambient temperature also increases.

Indirect evaporative cooling

Indirect evaporative cooling

 

How the solar ventilator cools will depend on the extent of cooling required.

In temperate climates, the solar ventilator operates as a solar chimney exhausting stale air to outside. As the heat differential increases between inside the solar ventilator and outside, controlled air flow is passively drawn outside. This can be boosted by the inline fan if required. With one or two strategically located vents on the cool side of the building,  a controlled cooling cross flow through the building would provide sufficient cooling in summer in most temperate climates.  

relationship between velocity and temperature to passively ventilate

relationship between velocity and temperature to passively ventilate

Possible ducting arrangement for cooler

Possible ducting arrangement for cooler