Definition: Outgassing (also known as “offgassing”) refers to the release of gas trapped within a solid. In the case of construction, the issue can cause poor indoor air quality if it is not addressed.
Usually a new house or an RV offgases so much that it irritates your eyes when you first walk in, but we have had none of that in our Transcend Tiny Home. We have searched long and hard to find the best solutions by using carefully curated materials and processes to make sure that we have clean air inside.
The phenolic fiberglass skin is baked at very high temperatures as part of the manufacturing process, causing any gases to boil off rapidly. It then is post cured at 300 degrees driving off all volatiles virtually eliminating offgassing.
Adhesives that are solvent based offgass more because they dry by evaporation. They oxidize, or must combined with oxygen, therefore they grab onto air molecules to dry and stabilize. We use adhesives that have a short open time an hour or less these types of new adhesives are reactive to air and humidity and set rapidly, not relying on evaporation thereby greatly reducing offgassing.
The high density extruded polystyrene foam panels are the best choice among types of foam with the least amount of offgassing. Plus we must age the foam to stabilize the moisture content before it gets fused into a panel giving it time to cycle through the majority of the outgassing before we use it. Then the foam gets sealed in between the two layers of phenolic fiberglass skins making for a very stable wall section.
By doing this, outgassing is controlled and greatly reduced. Building code requirements and fire safety requirements have us searching to find a balance between all of these issues.
So, that leaves us with drywall, interior paint, cabinets, and flooring as well as furniture as sources of outgassing. All of these products are getting better since awareness of the problem is more in the forefront than ever.
Here is the top level solution: An ERV is absolutely essential in a modern airtight house. We install one in every house.
Definition: Energy recovery ventilation (ERV) is the energy recovery process of exchanging the energy contained in normally exhausted building or space air and using it to treat (precondition) the incoming outdoor ventilation air.
An ERV slowly cycles fresh air into the house very much the same way that we breathe. As humans, we breath in fresh air and expel used air 24 hours a day, and that is what an ERV does for a house.
Plus an ERV recovers 95% of the heat for air conditioning making it very frugal. We have had an ERV test running now for a month and every time we go inside the Tiny Home it smells fresh and clean.
We prepared our steak fajita recipe on our food blog inside the home this week. We ran the cook top vent while we cooked and it removed most of the heat and smell. (By the way you have to crack the kitchen window while the vent is running.) The ERV handled the rest, and within 10 minutes the ERV slowed back down to deliver the needed exchange of air.
Our next step is to order an indoor air quality test to get real data.
Finding a workable balance of all of the issues is a challenging target. But we feel that any effort expended is worth it.