When measuring the amount of attic ventilation required, various variables must be considered such as vaulted ceilings, current ventilation (gable, ridge, roof), attic form, spacing and obstructions.
This will greatly simplify and facilitate the decision on the number, shape and location of solar attic fans. Let's discuss some important factors while determining the number of solar attic fans needed for your premises.
The first factor we must understand is the capacity of the solar attic fan. The capacity of a fan to discharge air is expressed in cubic feet per minute or CFM. Simply put, it indicates the amount of air the fan can exhaust per minute under optimal operating conditions.
Knowing the capacity of your fan, you can well determine the number of fans needed to cover your entire house.
The next step is the amount of energy or power consumed by the fan. Power consumption is always measured in watts. You can decide to use two fans with lower wattage rather than one that consumes more energy, depending on the space to be covered.
After all, the main idea of installing solar attic fans is to minimize energy consumption and its cost.
The size of the attic space on your roof is one of the basic factors in determining the number of fans you need for your premises. The size of your attic is measured in square feet. Determining the size of your attic is simple.
All you need to do is to multiply the length and width of your house. This will give you the size of your attic space in square feet.
The next factor to consider is the slope of your roof, or more precisely, the slope or pitch of your attic. The steepness of your attic roof is expressed as x/12, where x is the slope of your roof.
A low pitch or slope roof can typically be up to 4/12 or 18°, while a high pitch or slope roof can be up to 45° or 12/12. The slope of your roof is critical because it determines the amount of air space available in your attic.
Because a low-slope attic holds less air, you don't need many solar fans to get it out and draw in more cool air. This is also true for a steep roof, which may contain a lot of hot air and may require the use of multiple fans.
It is possible to drive hot air out of the attic by using solar attic fans, but this hot air must be replaced with cooler air from elsewhere. Fortunately, most homes have gable vents.
These are nothing more than air ducts placed at the edge of the roof under your eaves. This is an essential factor in determining the number of solar attic fans. In general, make sure you have four square feet of gable venting for every solar fan installed.
If the fence covers the gable vent, we must multiply this number by two to get a figure of eight square feet of gable venting for each solar fan.
From environmentally friendly to the most economical, solar attic fans can be a giant leap towards an off-grid lifestyle.