Should buildings be airtight?
The external envelope of a building should be as airtight as possible and this doesn’t only apply to Passive Houses. building damage caused by water vapour that is transported in air draughts can only be prevented by airtightness of the envelope (see illustration).
Why are air tight conditions necessary?
Airtightness is important for avoiding heat loss as it means less uncontrolled air movement in and out of the building. It can improve health by preventing substances that can provoke allergies being carried into the building via air leakage, and can also result in better sound insulation within the home.
Why must internal surfaces and joints be airtight?
If air leaks (uncontrolled) into the building envelope, the performance of the insulation can be degraded, which can lead to cold inner surfaces. In addition, if the building is not airtight, the ventilation rate may be increased, particularly in windy or cold weather.
Can we make an airtight house?
A continuous air barrier is essential Building the house with an airtight thermal envelope is one of the most difficult Passivhaus requirements to achieve. These joints were taped with a high-quality construction tape to provide a durable and airtight connection.
What is envelope leakage?
Envelope Leakage Testing is another term used for Blower Door Testing. An envelope leakage test is performed with a blower door. The blower door system measures the amount of air needed to create a change in pressure by calculating the air flow through the fan and its effect on the air pressure inside the building.
How do you ventilate an airtight house?
Supply Ventilation: Supply ventilation systems use a fan to pressurize your home, forcing outside air into the building and stale air to leak out through holes in the building envelope (bathroom fans, kitchens fans, etc.)
What are the key factors affecting the air tightness of domestic buildings and their internal air quality?
The level of IAQ within a building can be affected by a large number of factors such as: humidity, odors, chemicals, and outdoor air particles that are trapped within buildings.
Is concrete block airtight?
To begin, it is important to understand that concrete blocks are porous; this means they are not airtight in their own right. As a result the inner surface is parged (covered with plaster) to ensure airtightness. It is vital that the entire surface is thoroughly parged from the bottom of the wall to the very top.
What is airtight drywall?
Gypsum board drywall is, itself, a suitable air barrier material. The taping of drywall seams results in a plane of airtightness at the field of the wall. However, several steps must be taken to use this material property to create a continuous and complete air barrier system.
Is chipboard an airtight?
Durelis VapourBlock is a high-density ultra-low formaldehyde chipboard with a factory-fitted transparent airtightness and vapour control layer called TopFinish on one side. This board is specifically designed as a more reliable airtightness and vapour control layer compared to conventional plywood or OSB.
What is envelope testing?
Building envelope testing is the process of testing the physical separator between the interior and exterior of a building to determine if there are any air, water, or thermal leaks within the structure.
What happens if your house is too airtight?
Airtight house construction succeeded in decreasing energy costs, but most building science at the time hadn’t considered the potential disadvantage of such a tightly sealed house: poor ventilation in houses can actually also cause moisture buildup, leading to mold and IAQ issues.
What are the dangers of air tight buildings?
The dangers of air-tight buildings are three-fold: 1. POOR AIR QUALITY reduced fresh air into the building results in high CO2 levels which is bad for health 2. MOULD GROWTH Common sight at well sealed window frames as moist warm air cools when coming into contact with cold surface of external openings 3. OVERHEATING
What do you need to know about airtight construction?
Tight construction doesn’t involve magic, or any complicated skills, but it does take some training, knowledge, and care on the part of the builder. It involves using gaskets, special airtight electrical boxes, caulking]
Are there drafts in poorly airtight old buildings?
There are substantial drafts in poorly airtight old buildings even at moderate wind speeds but during periods of mild and calm weather air flows are inadequate. The air flow rate is too variable to maintain a consistant hygienic level of air exchange and high ventilation heat losses are inevitable.
How is the airtightness of a building measured?
The airtightness of a building can be measured by means of an air pressure test (airtightness test or “blower door test”) which determines the overall remaining leakage of a building. A fan is installed into a door or window to create a negative pressure in the whole house.