Think about the “tepee,” the mobile home of the plains Indian.
This cone-shaped contrivance is a stroke of pure genius that is the best possible example to describe “natural” ventilation.
In hot weather, narrow openings are allowed around the base of the tent. This allows cooler air at ground level to come in to the domicile.
An ingenious flap at the top of the cone can be opened in hot temperatures and closed in cooler times.
Voila! Ventilation. Cooler air in at the bottom is drawn upward to vent hot air at the top. The minor “breeze” thus created cools the people inside. The inside of a tepee properly vented is much cooler than outside because of the air movement.
During 50 years as a property manager, handyman, homeowner and landlord, I did learn a few things. One thing I learned about is ventilation.
Just to be sure of my facts, I consulted with two experts in the Heating Ventilation Air Conditioning (HVAC) business, one from Texas, one from Colorado.
The dictionary says to “ventilate” means to “take in fresh air, driving out foul air.”
Heat rises. Don’t argue with me. You should have learned this in high school physics. Heat rises, O.K.? So. Ventilation takes advantage of this natural phenomenon.
This summer has been extraordinarily hot. Many folks don’t benefit from the blessings of “central air,” and thus must depend on natural ventilation.
Sadly, lots of folks don’t understand how to take advantage of natural ventilation.
Our Texas expert reports "natural ventilation" is known in HVAC jargon as "passive cooling,” unassisted -- letting the laws of nature, God, work on your behalf.
There’s also assisted ventilation. If you have an attic fan, use it. But really you don’t need a bunch of electric fans if you cool your home or office passively, naturally.
The trick is, heat rises. In order to cool a room or a house, an exit must be provided for the hot air. Interior space that is closed up tight cannot be ventilated. It’s a contradiction in terms.
You may think you are “saving” the cooler air from overnight, but you are deluding yourself. Heat rises. If you let it go out, it will go out. If you imprison it, it will stay in.
Next: For ventilation to take place, there must also be an inlet. To take advantage of the natural flow of hot air upwards, a cross-draft must be created.
You want a source of cooler air. Since heat rises, the source of cooler air will be at a lower elevation in the structure.
The inlet will be a window in a basement, a first-floor bedroom, a shady-side den or library. An opening of an inch or two will be sufficient, but our Colorado expert recommends a wider opening for more total CFM (cubic feet per minute) flow.
The outlet will be in an attic door in the ceiling or an upstairs bedroom window, ideally the highest accessible point in the building.
Our Colorado expert testifies, “The key is to have a temperature differential. The greater that is, the better it works.”
Even if the cooler air is 90 degrees Fahrenheit, air temperature in the attic will be higher. The “cooler” air will be drawn upward by the rising, hotter air, ventilating to the outside.
While it is rising, it is reducing the interior temperature, creating a minor breeze, if you will.
Air in an unvented attic can become extremely hot, hot enough to burn the skin, to damage the lungs. However, it has been many years since I’ve seen an unvented attic.
A simple end-cap vent can be installed for very little money – and the entire structure can thus benefit from whole-house ventilation.
The trick is movement. Closed rooms or homes or buildings don’t, can’t, ventilate.
Airflow itself has a cooling effect. (Watch folks “fanning” themselves with a concert program. They are creating airflow to cause evaporation of perspiration and hence benefit from ventilation/cooling.)
Interior air which is reduced from 90 degrees to 80 degrees is “cooled.” This is a true fact. It may not be as cool as one would like, but it is an irrefutable fact. Air temperature of 80 degrees is “cooler” than air temperature of 90 degrees. Proper passive ventilation can reduce interior temperatures as much as 10 degrees – guaranteed.
Any cooling is a benefit. You may be most comfortable at 72 degrees, but you will likewise be more comfortable at 80 than you were at 90. Cooler is better, and unventilated is never cooler. Never. Physically impossible.
So be smart, be cool.
This cone-shaped contrivance is a stroke of pure genius that is the best possible example to describe “natural” ventilation.
In hot weather, narrow openings are allowed around the base of the tent. This allows cooler air at ground level to come in to the domicile.
An ingenious flap at the top of the cone can be opened in hot temperatures and closed in cooler times.
Voila! Ventilation. Cooler air in at the bottom is drawn upward to vent hot air at the top. The minor “breeze” thus created cools the people inside. The inside of a tepee properly vented is much cooler than outside because of the air movement.
During 50 years as a property manager, handyman, homeowner and landlord, I did learn a few things. One thing I learned about is ventilation.
Just to be sure of my facts, I consulted with two experts in the Heating Ventilation Air Conditioning (HVAC) business, one from Texas, one from Colorado.
The dictionary says to “ventilate” means to “take in fresh air, driving out foul air.”
Heat rises. Don’t argue with me. You should have learned this in high school physics. Heat rises, O.K.? So. Ventilation takes advantage of this natural phenomenon.
This summer has been extraordinarily hot. Many folks don’t benefit from the blessings of “central air,” and thus must depend on natural ventilation.
Sadly, lots of folks don’t understand how to take advantage of natural ventilation.
Our Texas expert reports "natural ventilation" is known in HVAC jargon as "passive cooling,” unassisted -- letting the laws of nature, God, work on your behalf.
There’s also assisted ventilation. If you have an attic fan, use it. But really you don’t need a bunch of electric fans if you cool your home or office passively, naturally.
The trick is, heat rises. In order to cool a room or a house, an exit must be provided for the hot air. Interior space that is closed up tight cannot be ventilated. It’s a contradiction in terms.
You may think you are “saving” the cooler air from overnight, but you are deluding yourself. Heat rises. If you let it go out, it will go out. If you imprison it, it will stay in.
Next: For ventilation to take place, there must also be an inlet. To take advantage of the natural flow of hot air upwards, a cross-draft must be created.
You want a source of cooler air. Since heat rises, the source of cooler air will be at a lower elevation in the structure.
The inlet will be a window in a basement, a first-floor bedroom, a shady-side den or library. An opening of an inch or two will be sufficient, but our Colorado expert recommends a wider opening for more total CFM (cubic feet per minute) flow.
The outlet will be in an attic door in the ceiling or an upstairs bedroom window, ideally the highest accessible point in the building.
Our Colorado expert testifies, “The key is to have a temperature differential. The greater that is, the better it works.”
Even if the cooler air is 90 degrees Fahrenheit, air temperature in the attic will be higher. The “cooler” air will be drawn upward by the rising, hotter air, ventilating to the outside.
While it is rising, it is reducing the interior temperature, creating a minor breeze, if you will.
Air in an unvented attic can become extremely hot, hot enough to burn the skin, to damage the lungs. However, it has been many years since I’ve seen an unvented attic.
A simple end-cap vent can be installed for very little money – and the entire structure can thus benefit from whole-house ventilation.
The trick is movement. Closed rooms or homes or buildings don’t, can’t, ventilate.
Airflow itself has a cooling effect. (Watch folks “fanning” themselves with a concert program. They are creating airflow to cause evaporation of perspiration and hence benefit from ventilation/cooling.)
Interior air which is reduced from 90 degrees to 80 degrees is “cooled.” This is a true fact. It may not be as cool as one would like, but it is an irrefutable fact. Air temperature of 80 degrees is “cooler” than air temperature of 90 degrees. Proper passive ventilation can reduce interior temperatures as much as 10 degrees – guaranteed.
Any cooling is a benefit. You may be most comfortable at 72 degrees, but you will likewise be more comfortable at 80 than you were at 90. Cooler is better, and unventilated is never cooler. Never. Physically impossible.
So be smart, be cool.
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