- #76

OmCheeto

Gold Member

- 2,204

- 2,655

Ratios!...

Not sure what you were after with R-Value, but Greg is asking about direct air leakage....

What's the ratio of heat loss from Greg's house via:

the lack of insulation

vs

direct air leakage

?

the lack of insulation

vs

direct air leakage

?

We know that Greg has a 3 story house, with one of the stories being at least partially underground, and from a previous post, the upstairs is unheated, so, I'll interpolate his above ground surface area as being 189 m^2. (1000 ft^2 floor area with 8 ft tall walls)

Using your temperature numbers, I calculate that with the fan on, he would be losing 635 watts.

With a nominal R-value of 13, his walls and ceiling will be losing 1815 watts.

Since we don't know his actual air leakage rate, nor his aggregate R-value, it's difficult for me to recommend a course of action.

Also, since we now know his bathroom fans have "back draft dampers" and he has exterior flaps, I would not recommend adding more flaps.

ps. obligatory graph:

This tells me, that even at 10% of the fans flow rate, it's still losing 1/27th as much energy as the house, itself.