IAQTexas

Attending (and sponsoring) the Humid Climate Conference this week. So many great speakers on so many different topics all centered around transitions in building in humid climates.

This is grey Mylar flex, commonly installed in the 1980’s. Its R value is R3.2 (when new and installed well). This is less than half of current code (R-8) in hot humid climates, the reason for additional insulation is not for energy efficiency, it’s to prevent condensation on the ductwork in the attic. If the insulation were installed here, this would drip into the porous insulation and stay wet for a longer time. Note the darker staining where it is currently wet, and the black staining (mold) on the sheetrock from when the insulation was installed. Try as we might, it is very challenging to completely air seal an attic where that moldy air can’t get into the living space.

This ductwork is less than 18 months old and moldy, both on the inside and the outside. Building science is the study of the system of interrelated systems that make up a home/building. While you can optimize those systems to achieve great IAQ, those same systems can also work against you. In this case all the systems led to this mold: poorly installed spray foam, duct leakage, undersized ductwork, oversized A/C, zoned system with a bypass duct, and outdoor air ventilation into the return.

This week is Indoor Air Quality Awareness Week and I wanted to post about some recent experiences with multiple clients lately. I have had multiple clients tell me that their HVAC company told them that if they added a “UV light” to their plenum and maybe replaced their supply plenum that the mold will “go away”. Two of these HVAC companies claim to be “indoor air quality experts”. It is important that consumers understand that HVAC companies are often times not IAQ experts and don’t really understand what is happening in your home and how electronic air purification really works. It is sad to see this information spread by “Trusted Experts”.

Fiberglass is a respiratory irritant that can be cancer causing. Leaving loose fiberglass in the airstream is bad for air quality as it can easily become airborne. The first picture is an example of this. Not only can the fiberglass become airborne, but also these extra porous chunks are more susceptible to holding moisture and getting moldy. Ductboard in general is a sponge for dirt and moisture, metal supply plenums are much better.

Electronic air purification isn’t going to fix the excessive moisture in the ductwork or in the home, so this is at best a band-aide solution, but rarely I see them have any impact at all. Most of the time I see UV lights in ductbaord, which degrade the binders in the fiberglass causing chemical offgasing and the fiberglass to become airborne. The second and third pictures are examples of this where the ductboard has turned white. Aside from that, electronic air purification is designed to alter the air chemistry in the home this inherently causing incomplete reactions and chemical byproducts. Loads of studies have been done on this to show the damage these devices can cause, I have studies for each technology: hydroxyl radical, ionization, bipolar ionization, UV, etc. so PM me if you would like those studies to read for yourself. Bottom line is: don’t do indoor air chemistry in your home and don’t use these electronic “Air Purification” technologies. Also, try to have a consultant in your home that cares about IAQ and doesn’t have some agenda like selling you a quick fix that suits them.