LV14842B - The method to decrease the noise caused by the rain falling on a windowsill and means for its realization - Google Patents

Abstract

Method for reduction of a noise made by falling rain on a metallic or a plastic windowsill, wherein said windowsill is provided with a noise and vibration dampening device coated on a surface of the windowsill.˙

Description

DESCRIPTION OF THE INVENTION

The invention relates to construction, in particular to elements of window construction that reduce indoor noise pollution. More specifically, it refers to a method and device for reducing the noise caused by rain falling on a window sill.

Analysis of prior art

Noise from the rain at night can have a significant impact on sleep, daytime on work capacity and communication. EU guidelines have been developed which, as a first level objective, aim to reduce outdoor noise at night to 55 dB.

Various solutions are known to reduce the noise caused by rainfall on window construction elements, which includes the placement of various blinds, curtains, films, additional layers of glass, sound-absorbing linings on or around the window pane. However, these structures only reduce the noise without eliminating its main cause, namely the effect of rainfall on the structural elements of the window, in particular the window sill.

In most modern buildings, including residential buildings, the window sills are made of metal or plastic. This plate is usually constructively connected to the window frame. As a result, window sill vibrations are introduced indoors and often result in the resonance of window construction elements, which amplify the noise.

The main type of rainfall that causes rainfall noise and window sill vibrations is rain. Hail, which can also be a source of intense noise, is a much less common phenomenon and is not addressed here.

Construction uses a technique to reduce vibration of metal and plastic window sills - vibration-reducing self-adhesive tapes that are attached to the underside of the window sills during construction, such as by Hanno Werk GmbH & Co. KG. Unfortunately, this solution does not apply to metal or plastic window sills that do not have such a tape applied during construction. The use of such a tape would be possible by replacing the windowsills in previously built buildings if it were done by industrial means, such as scaffolding or crane. Otherwise, such a replacement would only be possible on the ground floor for residents from a security standpoint. In other cases, the cost of such work would be prohibitively high. Therefore, there is a need for a solution to reduce window vibration, which would be applicable to window sills that cannot be accessed from outside without technical means, and which would also be suitable for individual use by citizens.

Technical problem and its solution

The technical problem that needs to be solved in this case is to reduce the noise caused by rain falling on the windowsill and to implement this technique. This technical problem is solved by applying a noise and vibration reduction coating on the window sill. Such a solution is possible only by finding suitable material that can reduce the impact noise and vibration caused by rain drops falling on the windowsill, can last without replacements and does not cause pollution and fire safety problems. It is important to ensure that it can be applied by the residents themselves from inside the room.

Typical rainfall parameters need to be determined before a window sill can be designed. The usual type of rain is determined by a number of parameters including drop height, intensity (liters of water per minute per square meter) and average drop diameter. In determining the frequency of rainfall of different intensities, the accepted division of IEC 60721-2-2 in Table 1 can be used.

Table 1

Classification of environmental conditions according to IEC 60721-2-2 Ed. 1.0 b: 1988, Part 2, "Environmental conditions in nature.

Rainfall and Wind "

The type of rain Rain intensity, mm / h Typical case drops diameter, mm Falling speed, m / s moderate to 4 0.5 to 1 1 to 2 intense to 15 1 to 2 2 to 4 strong to 40 2 to 5 5 to 7 rain gust greater than 100 greater than 3 greater than 6

Heavy rain parameters are used in the calculation to obtain the best noise reduction. It is inappropriate to use rainfall parameters as it will cause the overall noise level (such as thunder) to exceed the window sill noise.

The performance of a possible device can be determined by the ISO standard 140-18: 2006 Measurement of Sound Insulation in Building Elements, Part 18: Laboratory Measurement of Sound Generated by Rainfall on Building Elements.

For the study, an apparatus corresponding to the apparatus described in ISO standard 140-18: 2006 was set up and placed at a 5 degree angle to the horizontal plane (this is a typical window sill angle). A typical 0.30 x 1.2 m aluminum or polyvinyl chloride window sill, which was rigidly secured on three sides, was subjected to heavy rainfall water flow. Noise measurements were made on an uncoated window sill and on a window covered with various types of 0.3 x 1.2 m noise reduction device according to the invention. Polyurethane foam sheets of 10 to 25 mm thickness were used for noise reduction. Initial experiments have found that a device with a thickness of less than 15 mm gives insufficient effect, but increasing the thickness above 20 mm does not increase efficiency. Therefore, a 16 mm thick layer of polyurethane foam was used for further research.

During heavy rains, the size of the rain drops ranges from 2 to 5 mm. In order to disperse the energy of the droplet into the noise reduction device, the raindrop must either be stuck in the pores of the top layer of the device or split into several pores that become stuck in the pores. Thus, if the device has a pore size of 1.6 to 2.2 mm, it may trap rain drops up to 2 mm in diameter without breaking and up to 5 mm in 2 to 4 parts on the pore separating surface.

Another important parameter when selecting a noise reduction device is material density. At high density, water accumulates in the upper layer of the material and the noise reduction effect is minimal. Conversely, if the density of the material is too low, rain drops at high velocity can penetrate the material layer and reach the window sill, and even in this case the best noise reduction effect is not achieved. Therefore, in experiments, it has been found that reticulated polyurethane foam with open pores, average pore size 5 to 6 cm ^-1 , density 29 kg / m ³ , hardness 2.7 to 4.7 kPa, resistance 80 kPa provides optimal noise reduction. 120% relative extension before breaking.

Experimentally, it was found that the device described within the range of 100 to 3150 Hz provided about 15 dB (A) reduction in rain-borne noise when compared to a window without the device described.

DETAILED DESCRIPTION OF THE INVENTION

The proposed technique for reducing the noise caused by rain falling on a window sill or metal window sill is to glue the entire surface of the window sill with a damping device.

A layer of polyurethane foam is proposed as a silencer. Device thickness is approximately 15 to 20 mm, optimum 16 mm, number of pores from 5 to 6 per 1 cm, material density about 29 kg / m ³ , hardness 2.7 to 4.7 kPa, resistance 80 kPa, relative elongation before breaking 120%.

Polyurethane foam optimally contains additives that prevent it from overgrowing with plants. The material is flame-retardant. In an optimal embodiment, the polyurethane foam layer is provided with a single self-adhesive layer which retains the bond to the metal or plastic window sills for a long time. The device can be pre-fabricated in different colors, in several standard window sill sizes, or customized by on-site trimming as needed. It does not require any technical skill, is fast and secure and can be done from the inside of the room. The following examples illustrate the features and efficiency of the device.

Examples of realization of the invention

The examples illustrate the effectiveness of using the proposed device under different conditions. Example 1: Measurements were made in the city, during the day, comparing noise as a weighted average sound pressure in dB (A) in the range 100-3150 Hz at a distance of 1 m from the window sill to an open window sill (120x25 cm) with and without a silencer fitted. The results obtained during moderate rainfall are summarized in Table 2.

Table 2

Noise Measurements during Merena Rain

Daily Background dB (A) 47 Rain sound dB (A) fifty three Difference with background 6th Sound level with dB (A) 48.1 Net silence in dB (A) 4.9 Noise reduction,% 81.67 Difference from Background with Flies,% 2.34 Difference dB (A) 1.1

Example 2: Noise measurements during heavy rain

Table 3

Daily Background dB (A) 47 Rain sound dB (A) 60.74 Difference with background 13.74 Sound level with dB (A) 48.4 Net silence in dB (A) 12.34 Noise reduction% 89.81% % Difference from background with silence 2.98% Difference dB (A) 1.4

As can be seen from this data, the noise caused by rain falling on the windowsill increases the background noise by up to 2 dB (A) when using a silencer. As a result, even in heavy rain, it is expected that even in the case of outdoor noise levels below 48 dB (A) the increase in noise above the recommended limit of 50 dB (A) will not occur.

Advantages of the Invention

The proposed device for reducing the noise caused by rain falling on the window sill provides a reduction of 88 to 92%, which results in a 2 to 3% increase in background noise. Attaching the device to the window sill does not require any special technical skill and can be done with a suitable adhesive or self-adhesive device on any floor of the building in a short time. Material sizes are adjustable to typical window sills during the manufacturing process or at the application site. The material of the device does not accumulate dirt, does not overgrow with plants and is fire-resistant (flame retardant). An additional advantage is that such material effectively protects the windowsills from the presence of birds. Because birds' claws get stuck in the pores, the bird no longer returns to the windowsill after a difficult ascent.

Industrial Applicability of the Invention

The device can be used industrially in the construction of new buildings and rebuilding existing buildings or individually for the treatment of individual windowsills. The material for the offered device is industrially available in various colors with a self-adhesive layer already applied, which simplifies the placement of the device.

Claims (4)

1. Device for reducing the noise caused by rain falling on a window sill of metal or plastic, which comprises covering the surface of the window sill with noise and vibration damping layer. The device according to claim 1, characterized in that said layer is a reticulated polyurethane foam sheet. The device according to claim 2, characterized in that the sheet has a thickness of about 15 to 20 mm, preferably 16 mm, a pore number of 5 to 6 cm ^-1 , and a material density of about 29 kg / m ³ . Device according to Claim 2 or 3, characterized in that it is further provided with a self-adhesive layer to be attached to the window sill surface.