Passive Venting and Air Supply
One of the passive technologies we’ve designed into the house and hope to utilize is the passive fresh air vent. Airtight efficient homes require fresh air to supply not only a forced air heating system but simply fresh air to breath. If allergies to outside air is not an issue as in our case, there is no need to filter outside air before it enters the home, you need only acclimate that air so that you don’t have to waste energy to heat or cool it. This is done by pulling air from the outside close to the ground, through air intake tubes that run underground, then through your foundation and tie into your ventilation system. Tah dah!
Instead of using electric fans to pull the air, this system uses the natural high and low pressure zones that occur in the home when warm air rises to the ceiling. The low pressure on the floor is a vacuum which pulls for any air it can get. Instead of that air being yanked from wall sockets or under wall baseboards (you’ve all seen the black streaks on white carpet at the base of walls), the path of least resistance is through the tube.
The pulling of the air through the underground thermal mass acclimates it to roughly ground temperature (12ºC+-) in summer or winter before bringing it into your home. This is essentially what a component of a good HVAC system does. We’re guessing that with the right thinking we can tie this into the heat exchanger so that we bring the air to interior temperature even further and reduce humidity in the summer. This system is passive and replaces electronic methods that might have pulled air from the roof or soffit height wall vents. This passive vent is sometimes called the Earth Tube. More info at TheNaturalHome.com