How should a ventilation shunt be to comply with regulations?

Ventilation shunt. General requirements of the Technical Code in this matter

The shunt is one types of ducts for the evacuation of air or combustion products that was initially designed for use in apartment blocks. A shunt usually consists of a collective duct into which each individual duct discharges, always at the height of the upper floor. This allows several ducts to connect to a shunt without the risk that the already renewed air coming from another room can enter the next connected room.

The Technical Code for Building clearly specifies in its DB HS 3. "Health. Indoor Air Quality" that homes must have a general system of ventilation hybrid or mechanical with the following characteristics.

• Air will circulate from dry rooms to wet rooms. For this reason, dining rooms, bedrooms, and living rooms must have intake openings. Meanwhile, bathrooms, kitchens, and toilets will have extraction openings.
• The intake openings will be formed by air vents or fixed openings. The former must always be placed at a distance from the floor greater than 1.80 m. In the case of hybrid ventilation, the intake openings must communicate directly with the outside.

Specifications that a ventilation shunt must meet to comply with regulations

A shunt as a ventilation duct must also meet the specifications of the Technical Code. In this sense, they must be vertical ducts with a uniform section and lack obstacles throughout their length. They will also have a finish that hinders the accumulation of dirt. In addition, they will be practicable with openings located every 10 m., to allow for maintenance. When it comes to a collective shunt, it will not serve more than six floors under any circumstances, such that the ducts of the last two floors must be individual. The connection of the extraction openings to the collective ducts must be made through vertical branches, each of which will discharge into the duct located immediately below the next branch. All ventilation shunts, whether they are individual ducts or serve several homes, must be airtight for their pressure rating. Regarding the materials commonly used for ventilation ducts, metallic materials, those made with insulating material (fiberglass and rock wool), textiles, and those made with reinforced aluminum are usually used.

Extraction ducts for mechanical ventilation

Each extraction duct must have a mechanical fan located after the last extraction opening in the direction of the airflow. Several points can share the same fan except in the case of the extraction ducts of garages, which will have an independent one. For the sizing of extraction ducts, it should be noted that the section of each part of the ducts will be at least 225 cm2 reaching up to sections of 900 cm2 in sections where the flow is maximum.