Intelligent exhaust air ducting - not only for architecturally sophisticated buildings
Especially in office spaces, the expectations regarding fresh air supply and the associated air quality are very high. It is particularly important that the ventilation components comply with all sound insulation specifications and do not interfere with the interior design. Sound-absorbing transfer grilles for partition wall installation meet these requirements and are therefore a good choice not only for architecturally sophisticated buildings.
In air-conditioning concepts, the supply air and exhaust air ducting is often implemented spatially separately via ventilation ducts and air diffusers. Such "double" ductwork not only means additional costs, but also the space required for the air ducts often leads to the decision not to use exhaust air ducts and inlets in office spaces. In addition, windows and doors are often closed for undisturbed working. Nevertheless, the room must have a sufficient air supply. This is where the simple idea of the overflow element in conjunction with a room air conditioning system comes into play: As before, the supply air is routed via ducts from the central air conditioning unit to the rooms to be ventilated or air conditioned. The required amount of fresh supply air is introduced draught-free via corresponding air outlets in the ceiling, wall or floor. In this way, the best air quality is achieved in these rooms.
The extraction of exhaust air is also intelligently solved: Instead of being extracted in the individual office rooms, it is centrally extracted in the corridor or in similar areas with a subordinate function. The corridor then serves as an exhaust air duct - further exhaust air ducts from the office to this point are no longer necessary. Careful planning of the exhaust air ducting from the office rooms is nevertheless important. This is because walls and doors are now so tight that leakage is no longer sufficient to allow exhaust air to overflow into the corridor. In the past, doors were shortened or fitted with door grilles, allowing overflow at this point. However, these simple measures are no longer appropriate, especially where sound insulation and the prevention of telephonic sound transmission must be considered. Doors and other construction elements also weaken the sound insulation measure. For this reason, all components should be carefully selected to obtain the best possible sound insulation.
Drywall made of gypsum board is usually used between offices and adjoining rooms or corridors. To protect sensitive areas, double planking is already used here for acoustic reasons. The additional installation of sound-absorbing transfer grilles is the ideal solution for several reasons: the acoustic insulating effect of the wall construction is largely retained, and at the same time the air can overflow freely into the corridor or other rooms. The highly effective inner lining with integrated telephonic silencer ensures adequate sound insulation. INDUSILENT transfer grilles are supplied with Rw dimensions measured by the Fraunhofer Institute and provided with the corresponding test certificate. Based on this, the acousticians calculate the entire wall element.
In principle, the slimmer the slot, the less sound escapes. However, this also increases the pressure loss of the transfer grille. Therefore, the joint and the corresponding box should be selected as optimally as possible. Ideally, the right balance is achieved in the overpressure so that the air can move and overflow sufficiently, but at the same time a pleasant opening and closing behavior of the doors is ensured. As a guide, we recommend limiting the overpressure in the offices to a maximum of 10 Pa.
In modern buildings with tight building envelopes, sound-absorbing transfer grilles are now an intelligent, space-saving solution for exhaust air ducting. By centrally extracting the exhaust air in the corridors, further exhaust air ducts are saved. Air overflow elements are the best choice especially when high sound absorption is required, a low installation height is needed and a project-specific appearance of the air outlet slots is desired. Depending on the installation situation, INDUSILENT transfer grilles are available for different wall thicknesses. There is a choice of different construction types: With attractive decorative frames in any RAL colour or as an open shadow gap with optional cover frame can be selected depending on the desired design. Through the targeted use of architectural elements, an almost invisible installation is possible. This is why they are often used in architecturally sophisticated buildings, such as the new building of the University of Applied Sciences Northwestern Switzerland in Muttenz. At the architects' request, the slot of the overflow elements visible from the room was designed as a 2 cm high open shadow gap. This appears visually as a continuous black band over three elements. The overflow slots are visually unobtrusively integrated into vertically running wooden slats made of solid oak on the outside of the partition walls.
In order to obtain the best attenuation values and at the same time the ideal air volume with an acceptable pressure loss, planning is recommended consistently from the very beginning - between architects, planners and air-conditioning experts. This is because it is often recognised too late that the intended slot is not sufficient. A jointly prepared concept at the beginning prevents such unpleasant surprises. There are also important things to consider during direct installation: The gap between the wall opening and the neck of the transfer grille must be closed with suitable materials to prevent sound bypasses. The INDUSILENT transfer grilles are classified as non-combustible according to building material class A2 in accordance with DIN 4102. Another positive effect is the absence of fibres in the air flow. Kiefer takes great care to laminate mineral fibre insulation elements on 6 sides so that no fibres can enter the air flow.
The INDUSILENT enables the free transfer of air from room to room. The acoustic weakening of the partition wall as a result of installing the transfer grille is mitigated by the integration of a highly effective inner lining. Taking into account a maximum pressure differential of 20 Pa, specific air flow rates of up to 200 m³/hm are possible.
Kiefer Klimatechnik GmbH is a leading company in the field of ventilation, air handling and air conditioning technology. Our range of services includes consulting, planning and execution of systems for thermal comfort and industrial air conditioning, as well as the associated installation and maintenance. For more than three decades, Kiefer has also been selling high grade ventilation components worldwide, such as linear diffusers, wall passages, displacement outlets, light and acoustic sails, chilled ceiling panels and concrete core cooling systems, developed in the company's own laboratories.
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