Sojol's modes are determined by temperature sensors inside, outside and within the solar air heater. This enables the system to switch between modes to provide 24 hours ventilation throughout the seasons, in this way optimizing comfort and renewable energy gains.

As an example, one sunny day in winter in New Zealand with solar heated air flowing into the home, outside temperature at about 15C and solar radiation reaching nearly 1000Wh, and at an average volume of 660m3/hr, the supply temperatures measured 35C near the solar ventilator and 32C entering the building. Over an 8 hour period, solar air heating raised the ambient temperature by an average of 14C. (Since these results we have optimized the design even further by means of simulation iterations).

As an example of its potential during a cloudy and wet day in winter in NZ, one such day solar radiation hovered around a low of 200Wh, while temperature readings of the supply air still increased by an average of about 5 degrees C over an eight hour period. This temperature gain would increase or decrease depending on the supply air volume.

When necessary, an electric air heater can boost the temperature of the air to the desired temperature during such a cloudy day.

An additional inline air heater can by-pass the solar ventilator for night time winter heating supplying warm fresh air ventilation. A larger proportion of air flow can be directed to the bedrooms for night time. It is worth noting that bedrooms are often the second most common place to find mould growth, bathrooms being the first. Given that a large proportion of time is spent in the bedroom, fresh air ventilation in this part of the house shouldn't be neglected.

In summer, air can be passively removed out the solar ventilator, now acting as a solar chimney, creating a controlled cooling cross flow through the building. A pressure sensor ensures the home is always slightly positively ventilated. It detects if the home is closed up and redirects the air in the solar ventilator to self-cool. And in summer at night, fresh air flows through the solar ventilator providing cooler air than the outside temperature due to nocturnal radiation.

In hot climates where the outside air can be too hot by midday to draw into the building, an indirect cooler may be added to the system, paradoxically using hot air from the solar ventilator to more efficiently cool air.

It truly is a versatile renewable energy solution to ventilation.inline

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