GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Where to place fresh air intake / exhaust on a 2 story home?

tneicna | Posted in Green Building Techniques on

4B, 2-story home with an unconditioned attic and 2 different HVAC systems (1st and 2nd floor)

I’ve been improving the insulation in the attic (I now have R-60 with cellulose instead of R30 of fibreglass), I also air sealed the attic floor, as well as HVAC ducts with CCSF (2 inches), I’m happy to report that my HVAC runtimes during the hottest months are 40% less than the last 3 years. (Checked the historical averages from my tstat).

However, I have another issue that I am trying to solve: Fresh Air / Exhaust ventilation. (Co2 levels are elevated now, possibly due to HVAC system upstairs not running as often, plus it’s not actually pulling in ‘fresh air’ / exhausting from the attic via leaky ducts as much?) 

I have 2 bathrooms on the upper floors, 1 is the master and another one is in the hallway. Both have Broan bathroom exhaust fans. I’d like to put fresh air intake, or even a ERV somewhere upstairs, but I’m limited on where I could do an ERV because I do not believe there are ERVs that can be installed in unconditioned attics. I could install one in the ceiling upstairs, somehow. 

Some thoughts:

– A damper in the attic A/H to exhaust air (negative pressure) from the return box, and a 1st floor positive pressure fresh air intake).
– Or, I could just do a fresh air intake in the attic, attach it to the return box, theroritally, the positive pressure from the fresh air intake would exhaust from the bathroom exhaust fans? (the dampers on the Broans do not close all the way when the unit is off). 
– Or, a 1st floor ERV, with a dedicated damper in the attic to run at x? 

What do you think? 

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. Expert Member
    MALCOLM TAYLOR | | #1

    tneicia,

    Can you clarify what you mean when you refer to intakes, dampers, and exhausts "in the attic". Do you mean through the roof, or do you mean those things will occur in the unconditioned attic?

    1. tneicna | | #2

      Meaning, through the walls that go to the outside.

      Ie: Exhaust damper that connects to an outside vent - similar to a bathroom exhaust vent/dryer vent.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |