The airtight construction prevents moisture and moisture inside the building from being transported into the building envelope by unintentional air leaks. Humidity and humidity are mainly generated by daily activities such as heating, cooking, bathing, washing, breathing, etc. There is a significant risk that moisture in the building envelope will come into contact with a cooler surface and condense. Condensation inside the building envelope (« interstitial condensation ») increases the risk of damage to the building envelope. A space of only 1 mm wide allows an involuntary airflow sufficient to carry 360 g of water per day in the building envelope. There are many standards that define how air tightness testing should be performed, including several from astm, an ISO standard, the Air Barrier Association of America (ABAA) standard, and the UK-based Air Tightness Testing & Measurement Association (ATTMA) standards. There are a number of ways to incorporate an air pressure retarder into the construction of new homes, but two are popular: sealed plastic films and the airtight drywall (ADA) approach. 1. An airtight construction is necessary to protect the building envelope. In polluted areas, outdoor air can also be harmful to occupants by default – airtightness helps occupants breathe only ventilated and filtered air. Ideally, the airtightness plan will be fully developed before the end of the design phase and the start of construction. If we built houses like before, we would not be able to pay the energy bills and even with the high bills, we would still be cold in winter.
A large mid-nineteenth-century farmhouse could easily have used a coal-filled train carriage in winter – and would still be draft-prone and uncomfortable. Instead of backing down, we should look at cramped homes that don`t have moisture problems — and good indoor air quality — and learn from them. Even if the houses tighten, there is still room for improvement. In other words, with a little effort, many of the houses built today could be built even more tightly. Previous articles have repeatedly referred to a narrow construction. This article will gather what is known about narrow construction, show why it is a good idea, and explain how it is an integral part of the systematic approach to planning and building houses. Today, builders who specialize in tight, energy-efficient construction often have a reputation for building healthy, high-quality homes. But some people still remember the first mistakes and condemn the tight construction, citing the poor indoor air quality and excess moisture found in some of the first houses built as densely as possible. And medical professionals sometimes associate tight construction with indoor pollution without having an understanding of building science. It`s like an entrepreneur discussing brain surgery.
Some people have gone so far as to suggest that we build loose houses again. It is not very forward-looking. The airtightness of a building is often expressed as the leakage airflow through the building envelope at a certain reference pressure (usually 50 Pascal), divided by: With dense construction, healthy materials, controlled ventilation, and directly ventilated and sealed combustion heaters, you can have a dense home and good indoor air quality. If you think of a house as a system, a dense construction has many advantages over a loose construction. Most building scientists think that narrower houses are a great idea and the narrower they are, the better. Here`s how close and casual it is to compare. Airtight construction can be formed from many different materials and components. These materials and components must be clearly marked on the drawings as the airtight line.
Some typical materials used for airtight construction are; Wet plaster on masonry structure, reinforced concrete, oriented strand panels (OSB) with a suitable thickness and specially developed airtight membranes. In addition to the materials that make up the fabric of the building, windows, doors, curtain wall systems and skylights must be airtight components. No. Every building, whether airtight or not, needs a well-designed, installed and functional ventilation system. Plenty of fresh and clean air at pleasant temperatures should be made available to people in the building all year round. The air of infiltration – where it has penetrated through the holes in the building envelope – cannot and will not do so. Airtightness is an important requirement for any energy-efficient building, but not the most important (as is sometimes suggested in popular publications – the most important requirement is good thermal insulation). Example: Successful completion of the blower door examination is a necessary prerequisite for the operation of the passive house; But that`s not enough.
Example: A conventional aircraft hull is airtight (much more airtight than a passive house needs to be), but it is not insulated to the quality of the passive house In airplanes, there is a lot of heat available for cabin heating. Most European countries include in their regulations prescribed or recommended minimum airtightness values with or without mandatory tests. There are several countries (e.g. the United Kingdom, France, Portugal, Denmark and Ireland) where air tightness tests are required by law for certain types of buildings or in the case of specific programmes.  An airtight design prevents thermal energy from escaping through unintentional holes in the building envelope. The main reason passive houses require so little heat is the powerful building envelope, which reduces the movement of heat in and out of the building. Insulation plays a key role in preventing unwanted heat loss and therefore also airtightness. The air barrier preserves the insulation`s performance, which would otherwise be reduced by drafts through it. The air barrier also keeps the air warm inside the building and prevents it from getting lost through holes in the building envelope. You can read more about this particular aspect in the article: What is the passive house building envelope? No. The construction of the type « Breathing Construction » or « Breathing Wall » is the common name of steam permeable constructions.
It is quite possible to have a building envelope that is both vapor permeable (allows the movement of water vapor through the construction) and airtight (without draft). There are many examples of standard passive house buildings with a building envelope that is both « breathable » and airtight. Misconception #2: Cramped homes have moisture and mold problems. Some do, but excessive moisture and mold are also common in loose homes. Moisture and mold problems are often due to foundation or roof leaks, pipe leaks, poor construction, lack of mechanical ventilation, choosing the wrong ventilation strategy, or accidental ventilation. There are several voluntary programs that require minimum airtightness for the building envelope (Passive House, Minergie-P, Effinergie, etc.). Historically, the passive house standard, created in 1988, has been the cornerstone of the development of airtightness of the envelope, as these types of buildings require extremely low leakage levels (n50 below 0.6 ach). A number of studies have shown significant energy savings through the tightening of the building envelope.    The TECHNICAL REPORT of the ASIEPI project on airtightness of buildings and pipes estimates the energy effects of the airtightness of the envelope of the order of 10 kWh per m2 of surface per year for heat demand in a moderately cold region (2500 degree-days).  Experimental data showing the energy savings of good airtightness have also been published by the Building Research Establishment in the UK as well as in the special issue of the rehva journals on airtightness.  They conclude that 15% of energy consumption can be saved for space conditioning in the UK context, from 11.5 m3 / (m2 · h) to 50 Pa (average electricity) to 5 m3 / (m2 · h) to 50 Pa (achievable). To ensure that nothing stands in the way of a pleasant climate in the building, when creating the airtight envelope of the building, be sure to choose products that are free of residential toxins.
Indoor air has a higher water vapor content (absolute humidity) than outdoor air – if it is not dehumidified. In a cold climate, the ambient air is cooled during the flow from the inside to the outside (exfiltration).