Can anyone tell me some sort of a formula for obtaining how much ventilation a window opening gives?
Answer:
What do you mean by how much ventilation? Is there a wind or a draft or is it static air.
A simple formula for a gentle breeze blowing in through an opening 650mm x 20mm (i hope you're sure of your units, that's about 25 inches by 1 in) is
flowrate of air = (wind speed) x (opening area) x (air density)
For example, at 5 km/hr winds, and opening with area of 0.013 sq. meters, the flow rate is
(5000)(0.013)= 65 cubic meters/hr which is about 80 kg of air per hour.
If there is no wind, then it's all diffusion/conduction, assuming that there is a temperature difference between inside and outside.
In that case, a simple formula is
heat transfer rate = (conductivity of air)x(area of opening)x(temperature difference) / (thickness of insulating layer of air)
The last part is difficult to imagine and calculate, but I would estimate it at 10 cm.
For example, for a temperature difference of 5 degrees Celcius between inside and outdoors: (0.026 W/m-K)(0.013 m^2)(5K)/(0.1m) = 0.017W (very little, compare that with the power output of a 60 W lightbulb, which produces 60 watts of mostly heat)
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: