BREATHING OF THE WALL
The EIOS concept states that the separation between the warm and cold environments has to be made in a Non-Permissive thermal Insulation. The structure wall is maintained in a single environment (warm or cold), and when a temperature difference is applied, the wall dries unidirectional (inward or outward).
Ironically, even though EIOS is a Non-Permissive insulation, the structural wall “breathes” much better by eliminating the water/air/vapor barrier.
Any envelope wall is subject to the phenomenon of “breathing,” which normally has to be humidity absorption and disposal in porous materials. Under the current method of constructing walls, the breathing of walls is given by the air/vapor flow from warm to cold (or vice-versa) to the whole range from interior to exterior. The warm vapors that diffuse in the cold area will inevitably condensate.
The primary goal when the EIOS technology elaboration started was to eliminate the condensation phenomenon, which is unavoidable in vapor-permeable structured walls.
In general, any wall structure is permeable to vapor diffusion. This phenomenon occurs when there are temperature and pressure differences in between warm and cold gases, to which the airflow is added from cold to warm due to the lack of tightness. The cavity wall frames, walls, or roofs, have two major drawbacks:
The major lack of tightness, that allow an abundant airflow from cold to warm and vapor transfer from warm to cold;
Usually built of sensitive materials which are affected by humidity, and that once it dampens it grows mold and becomes subject to accelerated degradation.
The wall structure tightness is improved by applying foils and membranes to it to reduce condensation and its harmful effects. Expensive materials treated with non-ecological substances are used to counteract the degradation.
The establishment of any structure is based on the most circulated adage “walls must breath.” This expresses the limited understanding of the unknown phenomena (unperceived by human senses) that happens in an envelope wall. The regular term “breath” in construction is not wrong. Any wall made out of porous materials can absorb water that is then released by evaporation. Thus, the breathing of walls is a benefit that has to be encouraged.
So what are the unknown mistakes and misunderstood aspects that lead to so many problems?
The mistake is that the walls’ “breathing” is made from warm to cold throughout the transfer of vapors, all the way from inside to outside by air/vapor flow. Before the enunciation of the Principle of Avoiding Condensation, it was believed the wall and the thermal insulations were subject to the same permeability and “breathing” conditions. Here comes the big error of envelope walls which mainly have to form a separation between warm and cold temperatures but do not stop warm vapors diffusing (passing) to cold zones. The Principle of Avoiding Condensation is the missing link to the correct functioning of any thermally-insulated wall.
The improper solution development of breathing from warm to cold lead to the implementation of different solutions which in fact obstruct the wall drying even more. A few solutions used are the vapor barrier applied on the warm side of a wall (the only beneficial solution on reducing condensation), the water barrier used on the exterior behind the insulation, usage of the drainage plane, the ventilation between the wall and insulation that reduces insulation effect, etc. In fact, in many situations when there is a significant difference of temperatures, the foil or membrane applied as vapor retardant actually acts as a condensation surface for warm vapors passing through the wall system. In the roofing system, the airtight breathing membrane is practically the last surface which unloads the vapor flow during the cold weather.
The correct solution is given by the practical application of the Principle of Avoiding Condensation, meaning that warm vapor flow has to be stopped with a Vapor Impermeable Insulation System.
The application of the Vapor-Impermeable Insulation concept on the exterior (or interior) of an envelope wall acts as a separation between warm and cold environments in regards to avoiding condensation, keeping the structural wall in a single medium. The porous (breathable) non-airtight wall maintained in one single environment not only does not meet the dew point conditions or vapors’ over-saturation, but it also dries due to the unidirectional drying phenomenon.
The EIOS wall does not require any membrane, water/air/vapor retardant barrier, or foil of any kind. All options of tightness, waterproofing, vapor control, anti-condensation, insulation, and finishing works are replaced by the EIOS Non-Permissive Insulation Class. Virtually, EIOS Thermosystem is an all-in-one water/air/vapor impervious barrier and thermal insulation that solves all issues that can harm an envelope wall.
The implementation of the Concept of Avoiding Condensation requires’ viewing the wall as two distinctive elements:
The bearing structure which needs to take all mechanical loads applied to the wall, but does not have to function as an air and vapor barrier for the building that dones not even have to be water resistant;
The Non-Permissive EIOS Thermosystem that acts as an Environmental Separator between differences in temperature and humidity, the all-in-one water/air/vapor complete barrier and high-performance insulation.
By separating the design of the two components with distinct configurations and functionalities, the acting wall is released by layers that trap moisture and perform as a better aerated structure in a single environment, distinctive from the hydro-thermal insulation with extended efficiency.
Despite defying logic, the EIOS wall breathes much better than any other wall configuration and insulation system. Contrary to expectations, the structural wall and the EIOS substrate will experience a unidirectional drying effect by simply applying a temperature difference (e.g. by heating inside) when any other would system will increase its humidity.
Condensation water in building enclosures is above 1 lbs/ft² (3-6 kg/m²) during the cold season in regular continental climates, going above that in extreme climates.
EIOS projects and experiments reveal not only that condensation is zero but that the substrate on which EIOS is applied decreases in humidity content. The phenomenon was first called Unidirectional Drying, currently known as the Drying Effect.
The explainer presents the physical phenomenon that realizes the Drying Effect in the situation when the Structural Element is on the cold side (exterior) of the separated environments.
The EIOS Thermosystem is constructed and sealed so as to prohibit any vapors passing through it The condensation phenomenon is then avoided without the vapor diffusion from warm to cold. The small thermal flow that can slowly pass through the Non-Permissive Insulation by conductivity literally warms up the surface of the supporting structure. This localized heat creates a temperature difference between the back of the EIOS and the exterior cold environment. Vapors behind the insulation start moving from warm to cold, leaving a dry space. The dry environment and the heat difference make water evaporate and dry the materials involved.
The Drying Effect is helped by the fact that the Structural Element is not an airtight-construction.
Instead of having condensation, mold, and degradation, EIOS Thermosystem creates a Drying Effect for the structure!
Would this not be good to have for your home and building investment?