How to Answer the "Are Tight Houses Bad?" Question

June 11, 2015

When talking to homeowners or trade contractors about energy efficient construction one question is inevitable: Are tight houses bad? 

 

Here's the answer:

Tight houses are good because they lower energy bills and increase comfort.

In doing so, they reduce the amount of work that an HVAC system must do, so the system can be smaller.

This can save you money up front and improve your finished product in the form of better comfort and energy efficiency for your customers. 

(And here comes the big but ...)

But well-insulated and tighter buildings also behave differently from their leaky forefathers.  Controlled ventilation is critical on the inside to keep a steady flow of fresh air in the house.
 
This is a good thing. In the old days, we opened windows. You can still do this in a tight house, it's just that you won't need to.
 
One more big but:

If the inside of a tightly-built well-insulated wall gets wet, it is much more difficult for it to dry than a wall with no insulation. 

Uninsulated walls from 90 years ago can dry out when they get wet (which they inevitably do) because they also leak air and heat. Heat and air movement dry things out quickly (just ask your clothes dryer), so leakier walls can dry out before the moisture accumulates enough to become a problem.
 
That's why it is important when designing and building wall systems to think about how to keep the wall dry and how to allow it to dry if it does get wet. Material choices are important, but paying attention to gravity is a pretty simple, inexpensive, and effective way to shed water.
 
Tight houses won't tolerate puddles.
 
 

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