acousticsfan
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- Joined
- Aug 16, 2017
- Posts
- 2
I am astonished by the way in which this problem is being discussed. Basically, this is about noise from a building services system. That means that first of ll soundproofing measures are needed. There are three problems with HVAC systems. Firstly, there is disturbing airborne noise emitted by the unit and the pipes. Secondly, there is secondary transmitted structure-borne noise, which is transferred from the HVAC to the building envelope and emitted from it as airborne noise. Thirdly, there is noise coming from the openings of the HVAC.
The spectra and noise levels can all be measured easily with REW. This allows the amount of sound insulation, to be calculated. Do not confuse this with sound damping for room acoustic conditioning. Most manufacturers of such products provide white papers and the necessary formulas. Almost all of which can be solved using an Excel spreadsheet.
The first issue can be resolved with encapsulation or enclosure. The simplest solution is a construction using plasterboard panels. Ideally, these should be double-planked. If the noise level is high and low-frequency, a so-called double-shell wall is used. Details are available from any manufacturer of plasterboard walls. If the unit itself transmits vibrations to the building, it must be decoupled. To do this, the unit is placed on a heavy plate that is decoupled with polyurethane foam according to the mass-spring principle. Not just any polyurethane foam pads, but specialized products. These can be found on the Internet. Manufacturers of such products provide formulas for adjusting the pad size to the correct weight to adjust dthe resonance. Ideally, the resonance frequency should be set to approx. 10 Hz, then the system will be fully effective from 20 Hz upwards. The HVAC pipes can be decoupled from the ceiling with silencers so that no vibration is transmitted. The noise transmitted into the room through the pipes can be reduced with aluminum and glass wool insulation foil, depending on the spectrum amd level. If this is not sufficient, encapsulation is required, as with the unit itself. If noise escapes from the outlets, the problem can be solved with a silencer, as with an exhaust pipe. This is complicated because the air flow must not be reduced. Your HVAC specialist can supply ready-made silencers.
Once the room is quiet, you can take care of the room acoustic conditioning and, if it is already in place, to adapt it to the new conditions.
I wish you every success.
The spectra and noise levels can all be measured easily with REW. This allows the amount of sound insulation, to be calculated. Do not confuse this with sound damping for room acoustic conditioning. Most manufacturers of such products provide white papers and the necessary formulas. Almost all of which can be solved using an Excel spreadsheet.
The first issue can be resolved with encapsulation or enclosure. The simplest solution is a construction using plasterboard panels. Ideally, these should be double-planked. If the noise level is high and low-frequency, a so-called double-shell wall is used. Details are available from any manufacturer of plasterboard walls. If the unit itself transmits vibrations to the building, it must be decoupled. To do this, the unit is placed on a heavy plate that is decoupled with polyurethane foam according to the mass-spring principle. Not just any polyurethane foam pads, but specialized products. These can be found on the Internet. Manufacturers of such products provide formulas for adjusting the pad size to the correct weight to adjust dthe resonance. Ideally, the resonance frequency should be set to approx. 10 Hz, then the system will be fully effective from 20 Hz upwards. The HVAC pipes can be decoupled from the ceiling with silencers so that no vibration is transmitted. The noise transmitted into the room through the pipes can be reduced with aluminum and glass wool insulation foil, depending on the spectrum amd level. If this is not sufficient, encapsulation is required, as with the unit itself. If noise escapes from the outlets, the problem can be solved with a silencer, as with an exhaust pipe. This is complicated because the air flow must not be reduced. Your HVAC specialist can supply ready-made silencers.
Once the room is quiet, you can take care of the room acoustic conditioning and, if it is already in place, to adapt it to the new conditions.
I wish you every success.
