The invention relates to the field of construction, especially to window construction elements, which reduce indoor noise contamination. More especially it relates to a device for reducing the rain made noise level on windowsill.
Noise made by rain can significantly act on sleep quality at night, and work and indoor communication in the daytime. One of the most important aims of the EU guidelines is to achieve outdoors noise level decrease till 55dB at night. (http://ec.europa.eu/health/ph_projects/2003/action3/docs/2003_08_frep_en.pdf)
There are known numerous indoor noise reduction solutions for falling precipitation made noise on window construction elements. Described embodiments include placement of various blinds, curtains, films, additional layer of glass, sound absorbing shields in or around the window pane, inside or outside of the window. Unfortunately all these constructions just decrease the noise level but do not remove its main reason - precipitation falling on window construction elements, especially on windowsill. Unfortunately all these constructions just decrease the noise level but do not remove it completely.
Windowsills in majority of the modem buildings, including residential buildings are made from metal or plastic plate. Usually this plate is constructively associated with the window frame. In such a way windowsill vibrations are introduced indoors and often cause the resonance of window construction elements, which increases the noise.
Rain is the main type of precipitation, which makes precipitation impact noise and windowsill vibrations. Hail which can be reason of more intensive noise is uncommon that is why it is not described in this case. Another known noise insulators are disclosed in
Unfortunately the above described solution is applicable just for metal or plastic windowsill wherein the tape is not laid during construction. For already built buildings this kind of tape can be used only in changing windowsills using industrial devices, namely, the scaffolding or crane. In another situation from a safety point of view change like this kind of works can be realized just for ground floor residents. For the other floor residents' costs of this type of works are financially high.
Because of the above described situation solution of windowsill made vibration reduction is needed. Preferred embodiment should be useable for windowsill, reachable from outside without technical devices and also be adjustable for individual residential usage.
Technical problem is absence of a device for reducing a noise made by rain falling on a windowsill.
Technical problem is solved by deposition of noise and vibration decreasing coating on windowsill.
Such a solution is possible only in creating suitable material, which can reduce impact sound and vibrations made of raindrops falling on the windowsill. Additionally described solution must serve for long term without degradation, not causing pollution and fire safety issues, can be installed by residents from inside of a building.
Typical characteristics of rain must be cleared out for construction of suitable device for lying on the windowsill. Type of rain describes several parameters including height of raindrop falling, intensity (liters of water per square meter) and average drop diameter. Rain classification IEC 60721-2-2 specified in Table 1 can be taken as a reference to determine the frequency of different intensities.
Heavy rain parameters were used in calculations to reach the most effective noise reduction.
Extreme rain parameters are inappropriate for noise level on windowsill calculations because overall level of weather made noise (for example, thunder) is higher.
Efficiency of possible device can be detected by ISO 140-18:2006 standard "Measurement of Sound Insulation in Building and of Building Elements, Part 18: Laboratory Measurement of Sound Generated by Rainfall of Building Elements."
For this research was made device described in ISO 140-18:2006 standard. This embodiment was tightly fixed on three sides in 5 degrees (typical windowsill angle) against the horizon typical aluminum or polyvinylchloride windowsill by size 0.30 x 1.2 m. Water flow against it was identical to heavy rain parameters.
Noise measurements was made for windowsill without cover and covered with different types of 0.3 x 1.2 m size noise reducing devices.
Polyurethane foam plate with thickness 10 to 25 mm was used for noise reduction. Preliminary experiments showed that the device with thickness less than 15 mm as well as the increase of thickness over 20 mm do not provide adequate efficiency. That is why 16 mm thick polyurethane foam level was used for further researches.
Size of raindrops can be from 2 till 5 mm during very heavy rain. In order to achieve power dissipation in noise reduction device, raindrop must stuck on surface of the device or must be broken down into several parts that get stuck in pores. In such way raindrops with diameter to 2 mm can stuck in device pores separating surface with diameter 1.6 to 2.2 mm without breaking down and with breaking in 1-4 parts if diameter is up to 5 mm.
Second the most important parameter for selection of noise reduction device is density of material. Water accumulation in material upper part can be observed in high density wherein noise reduction effect is minimal. If material density is to small - opposite situation can be observed - raindrops with high falling speed can break through material layer and reach the windowsill. In this situation the best effect of noise reduction is not reached as well. That is why the optimal noise reduction could be made by reticulated polyurethane foam material with open pores, with average pore count 5 - 6 cm-1, density 29 kg/m3, hardness 2.7-4.7 kPa, durability 80 kPa, 120% (relative) elongation before breaking.
Experimentally was found that said device in the range of 100-3150 Hz can provide around 15 dB (A) reduction in rain induced noise level, comparing with windowsill that does not have said device.
Proposed device for noise reduction of falling rain made noise provides noise reduction for 88 - 92% expressed as increase of background noise for 2 - 3%. Device fixation on windowsill is easy and do not ask any special technical skills, with suitable glue or self-sticking type. Fixation can be done in short time on any floor of the building. Size of material can be adjustable to windowsill size during production or at the place of usage. Material of device does not accumulate dirt, avoid plant growth on it and is fire safe (flame retardant).
Additional advantage is that it protects windowsill from bird stay. Bird claws stuck in the pores and complicate the taking off, so they do not get back anymore.
The present invention provides a device for reduction of noise of falling rain for metallic or plastic windowsill of window, wherein an upper surface of the windowsill is covered (glued) by noise reduction device. As a noise reduction device is polyurethane foam layer. Thickness of the device is about 15 - 20 mm, optimal 16 mm, amount of pores is 5 - 6 pores on 1 cm2, density 29 kg/m3, hardness 2.7 - 4.7 kPa, durability 80 kPa, 120% (relative) elongation before breaking.
In optimal case polyurethane foam contains additives that avoid plant growth on it. Material is fire safe (flame retardant). In optimal variant polyurethane foam layer has one self-sticking layer, which keeps cover connection with metallic or plastic windowsill for long term. Device can be industrially produced in several colors, for different sized standard windowsills or can be adapted by cutting at the place adjusting to windowsill size during production or at the place of usage. Installation does not need any special technical skills, it is fast and safe, can be done from the indoor of the building. Device traits and effectiveness is shown below described examples.
In given examples are shown efficiency of device in different conditions.
Measurements was made in the rural territory on daytime, comparing noise as A-weighting average sound pressure dB (A) in frequency range 100-315 Hz 1m away from aluminum windowsill (120x25 cm) with and without noise reduction device on open window. Results in moderate rain are described in on Table 2.
Above mentioned data show the falling rain made noise on windowsill with noise reduction device increases background noise not more than 2 dB(A). With this we can expect that noise level in rooms will not exceed recommended 48 dB(A) limit, wherein even during very heavy rain noise level will not exceed 48 dB(A).
Device can be industrially applicable for new buildings during construction, for reconstruction of existing buildings or individual windowsill covering. Material for described device can be industrially produced with different colors, with self - sticking layer, what simplify the application.
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