Insulation Measures Research Articles

The Use of Sound Absorbing Shading Systems for the Attenuation of Noise on Building Façades. An Experimental Investigation

The problem of solar irradiation in building façades with large windows is often solved with the use of external shading devices, such as brise-soleil systems, but their potential acoustic effects on building façades are usually neglected. The purpose of this work is a preliminary consideration of the acoustic behaviour of brise-soleil systems and, furthermore, the evaluation of the possibility to improve their performances, in terms of Sound Pressure Level (SPL) abatement over glass surfaces. The paper reports the results of a study on two portions of the same office building, with shading devices installed in front of large windows. Both airborne sound insulation measurements and SPL measurements over the glass surfaces of the windows were carried out to compare different situations, with or without louvers, and with sound absorbing experimental louvers as well. Results show that the louvers' presence can produce an increase in the SPL over the glass surface as a consequence of the reflection of the sound. Results further show that sound absorbing louvers improve the noise protection of the system, in terms of the SPL reduction, over glass surfaces, cancelling out the negative effect of the standard shading devices.

Sound Transmission between Rooms with Curtain Wall Façades: A Case Study

Curtain walls have reached good performances in terms of façade sound and thermal insulation, as well as solar protection. Nevertheless, the sound insulation performance of the partition between adjoining rooms with continuous curtain wall façades is often reduced by the presence of direct and flanking transmission through the junction with the façade itself. In this work, flanking and direct structural transmissions are analysed with reference to the joints of the mullion of the curtain wall with lightweight plasterboard partitions. Airborne sound insulation and vibration measurements were made in two adjacent rooms affected by the acoustic problems determined by the curtain wall joint. Traditional acoustic measurements, carried out according to EN ISO 16283–1, highlighted problems in sound insulation between rooms, but without any indication on different sound transmission paths through the wall. Vibration measurements were made for every part of the system (frame columns and beams, window panes, plasterboard wall, plasterboard false ceiling, etc.) to better understand the sound transmission paths in these kinds of structures. In this paper the results of this analysis are presented. Moreover, taking into account previous works and measurements made in this research field, different solutions for curtain wall structures are analysed and technical suggestions are given to improve airborne sound insulation between rooms separated by partitions mounted up to metal frames.

New measurements of multilayer insulation at variable cold temperature and elevated residual gas pressure

New MLI measurements at the TU Dresden flow type calorimeter have been carried out. Specimens of 20 layer double side aluminized polyester film were tested. A cylindrical cold surface of 0.9 m2 is held at the desired cold boundary temperature between approximately 30 K and 300 K. The heat transfer through the MLI is measured by recording the mass flow as well as the inlet and the outlet temperature of the cooling fluid. Measurements at varied cold boundary temperatures have been performed. Moreover the effect of an additional vacuum degradation - as it might occur by decreasing getter material performance in real systems at elevated temperatures - is studied by a controlled inlet of nitrogen gas. Thus the vacuum pressure was varied over a range of 10-7 mbar to 10-2 mbar. Different cold boundary temperatures between 35 K and 110 K were investigated. Test results for 20 layer MLI are presented.

Sound Insulation of Building Elements at Low Frequency: A Modal Approach

In typical laboratory volumes (50-80 m3) and at low frequencies (50-100 Hz), the acoustic field is non-diffuse due to the presence of source and receiving room modes. Under such conditions, standard sound insulation measurements and descriptors are not adequate to correctly characterize the insulating property of partitions or flooring systems. The «modal approach» allows to evaluate the airborne sound insulation by the determination of modal transmission loss, or modal sound insulation, of a single mode passing through the partition. Proper normalization terms and an extension method to one-third octave bands are also introduced. The same approach is applied to impact sound insulation measurement.

Calculating sound insulation of a sandwich structure on the basis of the «inverse matrix» method

Multilayered structures are widely used in housing construction, shipbuilding, aviation and space-rocket engineering. In designing such structures it is necessary to estimate their sound insulation capacity for the forecasting of levels of noise taking place in this or that premise or compartment. The paper presents a methodology of calculating sound insulation of a multilayered structure developed on the basis of solving wave equations in each of the layers taking into account the incident angle of sound waves and losses in layers; introduction of boundary conditions establishing equality on the borders of media of normal oscillatory speeds and acoustic pressure; drawing up a system of algebraic complex equations and a matrix equation corresponding to them; drawing up an inverse matrix of factors at functions of acoustic pressure. Examples of calculating factors of sound insulation for multilayered structures with various parameters are presented (superficial weights, thickness of layers, various incident angles). A graphic comparison of the results of calculations using the methods of inverse matrix and the impedance method as well as a graphic comparison of results of flight-design measurements (FDM) of the sound insulation of a regular head part, consisting of layers of coal tape, fiber glass fabrics, aluminum honeycombs and a layer of polyurethane foam are given. The results of calculation using the inverse matrix method are given and the advantage of the method is emphasized.

Justification of standardized level differences in rating of airborne sound insulation between dwellings

It has long been recognized that single-number quantities R′w, DnT,w or Dn,w result in different conclusions in objective rating of airborne sound insulation between dwellings. The difference between the values of these single-number quantities (SNQ), however, does not prove which of them describes the sound transmission between rooms most correctly. The main object of this article was to study which SNQ correspond best with transmitted living sound levels in buildings when reverberation time, volume of receiving room and sound insulation are taken into account. Data of 100 field measurements of airborne sound insulation were collected as well as 207 reverberation times of furnished rooms. The transmitted sound levels of living sounds were evaluated on the basis of known living sound spectra and measured level differences D. The results show that the SNQs standardized to reference reverberation time of 0.5s lead in all cases to best correlation between the SNQs and the sound levels of transmitted living sounds. It was also checked whether the rating by DnT,w would lead to higher transmitted sound levels of living sounds in larger rooms, but this was not detected. The use of DnT,w makes rooms of different volumes equal in regard to required sound insulation between them. It is thus justified to replace R′w with DnT,w as the SNQ for rating the airborne sound insulation. Widening the frequency range down to 50Hz or up to 5000Hz did not give noteworthy improvement in the correlation.

Methods of field measurements of facade sound insulation

The purpose of this article is to describe generally usable methods to measure the sound insulation of a facade in cases where a setup according to standards such as ISO 140/5 or ISO 16283/3 cannot be achieved. The methods discussed use a loudspeaker as the source of a test signal since background noise on the interior receiving side in many cases prevents the use of traffic as a noise source. The measurements presented in this article have been made using two loudspeaker positions at different angles. Three different ways of placing the microphone are considered. The microphone can be placed in fixed points directly on the facade, in fixed points at the same distance in front of the facade, or swept in front of the facade. The data presented are all taken from actual field measurements. The results are shown as a comparison between the levels acquired and the uncertainty associated with the different methods. (C) 2015 Institute of Noise Control Engineering. (Less)

Acoustics and new learning environment – A case study

This study presents the results of an acoustic performance evaluation of classrooms and their corridors on a test area of the Finnish Oulu Normal School. The project, “Spaces for learning and creation of new knowledge”, was organised by Rym Ltd and was a re-design pilot study where spatial analysis of some new schools and new forms of future school design have been made.Two different acoustical setups were evaluated by measurements of the reverberation time, sound pressure level (A-weighted equivalent level, LAeq), and sound insulation. Other acoustical parameters were also measured via sources of reverberation time to verify the difference of the test rooms. Speech Transmission Index (STI), disturbance radius (rD), spreading attenuation (D2,S), Clarity (C50), and Rapid Speech Transmission Index (RASTI) were calculated. Measurements of noise followed the Finnish guidelines. Measurements of reverberation time and sound insulation followed the International Standards ISO 140-4, ISO 140-5, ISO 717-1, and ISO 3382.The acoustic quality of the classrooms was analysed based on the measurements’ results (sound insulation and reverberation time), which were compared with the reference values found in the Finnish Standard SFS 5907. Results revealed good acoustical quality of the surveyed classrooms, for both test setups studied. The soft carpet on the floor made the acoustical performance of corridor areas usable for educational purposes. However, the sound insulation and background noise level of all the classrooms did not meet the guidelines of Finnish Standards. Discussion on new learning concepts and acoustical design reveals that new tools for the evaluation of learning spaces should be developed.

Seasonal acclimatization determined by non-invasive measurements of coat insulation.

Seasonal acclimatization in terrestrial mammals in the Northern Hemisphere involves changes in coat insulation. It is more economical to provide increased insulation than increased heat production for protection against the cold. This study was done to test a technique for the non-invasive measurement of mammal coat insulation and to measure coat insulation over several seasons on captive exotics. The working hypothesis was that species that have no coat or have a coat that does not change seasonally do not acclimatize seasonally. Three surface temperature readings were measured from the torso area. The insulation was calculated using measured metabolic rates and body temperature when possible. The African elephants, giraffe and okapi did not acclimatize with average maximum insulation values of 0.256°Cm(2) W(-1) . The Amur tigers and mountain goats acclimatized to seasonal ambient conditions by increasing the insulation values of the hair coats in the cold with an average maximum insulation values of 0.811°Cm(2) W(-1) . The cold adapted species are more than three times more insulated in the cold than the equatorial species. The husbandry implications of exotics that have no ability to acclimatize to Northern Hemisphere seasonal ambient changes are profound. Giraffe, African elephants, and okapi when exposed to cold conditions with ambient air temperatures below 21°C will use body energy reserves to maintain a heat balance and will require housing that provides ambient conditions of 21°C.

Mechanical and thermal tests of an innovative environment-friendly hollow block as self-insulation wall materials

Nowadays, energy dissipation of buildings has caused serious problems to the environment for leading to overuse of resources in China. To reduce energy consumption and protect the environment, shale that widely distributed in China and the waste, including both building waste and industrial waste are used as raw materials to manufacture fired hollow blocks with 29-row holes which ensure the insulation properties and reduction of weight. As samples, 365mm×248mm×249mm rectangular fire hollow blocks with density of 850kg/m3 were produced to study the mechanical and thermal properties of this wall material. The results satisfied the relevant Chinese Standard, and the block has a high compressive strength and reliable insulation performance comparing with fired common brick or other hollow blocks. Because of the excellent self-insulation characteristics, the blocks could be used directly as wall materials without requiring the usage of special insulation measures in masonry structures, which mean that this new-type material could reduce the cost of housing construction and had broad application prospect in masonry structures. Therefore, using this block could not only cut down the consumption of energy, but also could ease the pressure applied on the environment.

Revision of international standards on field measurements of airborne, impact and facade sound insulation to form the ISO 16283 series

This paper gives the background to the main technical changes concerning the field measurement of sound insulation in the new ISO 16283 series of standards for airborne, impact, and façade sound insulation. These changes were: (1) inclusion of only one-third octave bands without an option for octave band measurements, (2) indication of a preference for standardised (rather than normalised) sound insulation descriptors, (3) introduction of spatial sampling using manual scanning with the operator inside the source and/or receiving room, (4) introduction of a low-frequency procedure for one-third octave bands below 100 Hz in room volumes below 25 m3 using (a) corner measurements to determine the spatial average sound pressure level and (b) the 63 Hz octave band rather than one-third octave bands to measure the reverberation time, (5) alteration of the requirement on the source room spectrum for airborne sound insulation, (6) clarification of the loudspeaker directivity requirements and (7) introduction of the rubber ball as an option for impact sound insulation measurements.

Strategies for cost efficient refurbishment and solar energy integration in European Case Study buildings

There are numerous residential building typologies in Europe, which require differentiated strategies for building rehabilitation to obtain the lowest payback and highest energy savings. Building integrated renewables can provide some or most of the building energy demand with a strong dependency on climatic conditions. Within the project “holistic energy-efficient retrofitting of residential buildings” (HERB) in the European Union seventh framework program, the most appropriate way of saving energy and supplying building integrated renewables in 7 European countries is sought. This study presents an energetic and economic comparison between energy efficient refurbishment of the building envelope and the integration of renewable solar energy technologies for different climatic conditions.A range of dynamic multi-zone simulation runs were done in EnergyPlus increasing the thermal resistance of the building envelope elements from the national reference energy standard up to a low energy standard. For the given energy demand, the solar energy integration potentials providing electricity and heat are investigated using the simulation environment INSEL. Finally, cost analyses are done to find the financially optimum strategy for saving energy with building rehabilitation or producing energy with renewable technology integration.It could be shown that building rehabilitation becomes less cost and energy efficient with decreasing geographical latitude while renewable integration increases in relevance. Building insulation measures offer much higher savings than renewable production in more Northern locations even though with slightly higher specific costs. The measures suggested are now implemented in 12 building projects within the European project focusing especially on innovative materials and renewables.

State of field measurement of facade sound insulation in buildings: evaluation of proficiency testing data according to ISO 140-5:1998

The ISO 140-5:1998 standard specifies the testing methods to evaluate the sound insulation in buildings and building elements for facades. Three rounds of a proficiency testing scheme for airborne sound insulation measurements have been performed according to the methods specified in the standard for a whole facade by using an external loudspeaker as the noise source. The adequacy of the intercomparison is guaranteed by means of the assessment of global precision criteria in compliance with the scope stipulated by the normative references in order to determine the reproducibility limits in a regulated measurement method. To evaluate the participant performance, the corresponding combined scores as composite indexes are calculated, so if this assessment is performed along a certain number of rounds, it will remark the participants that show an overall satisfactory performance by monitoring their achievement over time. Therefore, in order to establish a reference value in terms of precision level, an approach based on the development of a collaborative test in controlled conditions is proposed. The goal is to provide reliable and updated criteria for the evaluation of repeatability and reproducibility limits in this field, particularly in those scopes in which nowadays there is no normative reference or this is very poor. Furthermore, these prescribed values of precision should be verified regularly, as well as the definition of practical conditions of application.

Evolution of ASTM E90 for measurement of sound transmission loss and related standards

The history ASTM E90 for measurement of sound transmission loss will be traced from the initial release of the first tentative standard in 1950, identifying significant changes that have occurred with each revision. To a lesser degree, the history of ASTM E413 on the sound transmission class, ASTM E1322 on rating outdoor-indoor sound transmission, ASTM E336 for measurement of sound isolation and insulation in the field, and ASTM E966 on outdoor to indoor measurements will be discussed.

Application of comprehensive thermal insulation measures for maintaining body temperature during period of liver transplantation

Objective To evaluate the effects of comprehensive thermal insulation measure for maintaining body temperature during perioperative period of liver transplantation for the late hepatic alveolar echinococcosis, and provide theoretical basis for improving the success rate of the operation. Methods A total of 18 patients undergoing liver transplantation for the late hepatic alveolar echinococcosis received comprehensive thermal insulation measure. The changes of nasopharyngeal and rectal temperature, pH, heart rate and blood pressure were monitored in the whole process of operation to justify the effective. Results After 5 min the new liver reperfusion, the nasopharyngeal and rectal temperature were (35.78±0.69) and (35.97±0.65)℃, and the value of pH decreased dramatically to (7.29±0.08), but the heart rate increased to (100.58±5.47) times/min (P<0.01). The systolic blood pressure were (82.21±10.45) and (83.59±12.71) mmHg during no liver period and 5 min new liver reperfusion (P<0.01), but all above indexes became normal after 30 min reperfusion. Conclusions During perioperative period of liver transplantation for the late hepatic alveolar echinococcosis, comprehensive thermal insulation measure can maintain the body temperature and other vital signs and effectively prevent the occurrence of intraoperative hypothermia. Key words: Echinococcosis, liver; Liver transplantation; Perioperative period; Comprehensive thermal insulation measure

Satisfaction with sound insulation in residential dwellings – The effect of wall construction

AimThe aim of this study was to compare the acoustic satisfaction in residential multi-storey buildings with different wall constructions with a similar weighted sound reduction index R′w: Heavy construction (monolithic concrete walls) and Light construction (staggered double walls). Light constructions are known to have a lower sound insulation especially at low frequencies. Our research question was does this difference affect the overall acoustic satisfaction among occupants. Materials and methodsFour and two residential multi-storey buildings were chosen to represent building types Heavy and Light, respectively. A questionnaire was distributed to each dwelling. Seventy-two and eighty-seven respondents were obtained, respectively, with response rates of 62% and 54%. Some sound insulation measurements were carried out for verification purposes. ResultsAs expected, the airborne sound insulation was worse below 160 Hz in building type Light, while the R′w values were nearly equal, 56–57 dB. The satisfaction with sound insulation did not differ between the two building types. All neighbour noise sources were rated equally disturbing in both building types. The building types did differ from each other with respect to the effects of noise on sleep. ConclusionsThe results suggest that when the airborne sound insulation is close to 55 dB R′w, the construction type does not necessarily affect the acoustic satisfaction. The results also suggest that R′w explains better the subjective rating of sound insulation than R′w + C50–3150.

The effect of high thermal insulation on high thermal mass: Is the dynamic behaviour of traditional envelopes in Mediterranean climates still possible?

The paper aims at studying the effect of both high thermal insulation and high thermal mass techniques in buildings dynamic behaviour in Mediterranean climates. The two techniques can lead to conflicting requirements when considering winter and summer conditions, or even high daily temperature ranges. Therefore, the best solution for the summer can be the worst solution for the winter. It is necessary to identify insulation measures that conserve the mass dynamic behaviour.Experimental investigations were carried out on a single-family house to characterize the behaviour of two walls with different thermal inertia. Thermal simulations made it possible to explore different retrofit configurations also including dynamic strategies. The solutions were compared on comfort, energy savings and global cost.The study shows that the most suitable intervention is the maximization of the internal heat capacity and the introduction of an external insulation layer sealed in wintertime and ventilated in summer, thus maintaining the existing massive envelope seasonal dynamic behaviour by alternatively maximising thermal barrier effect and heat loss. Considering this, the authors introduced a recently patented dynamic system that reduces both summer discomfort levels and consumption, respectively, of about 20% and 43% respect to the worst retrofit solution.

Exploring the road less travelled in energy reduction: More comfort with less energy, but is comfort always essential?

The risks associated with climate change, resource scarcity, overreliance on fossil fuels, rising fuel prices and the threats to national securities are all compelling reasons for finding alternative/greener energy sources as well as for reducing our energy consumption. For the demand side, energy efficiency has been the main strategy utilised so far; in buildings, this often means a focus on technologies capable of delivering the same or better levels of comfort, with less energy. In the last decade, however, there has been an increasing awareness that technology and engineering alone do not deliver the expected energy savings, often because of the ‘misuse’ and/or ‘abuse’ of such energy efficient technologies from building users. Hence, greater attention is being paid to occupant behaviour, both in research and policy circles. The role of behaviour and behaviour change within the context of energy reduction can be grouped under two themes/strategies: (1) Ensuring that existing and new energy efficient technologies are adopted, and used appropriately; (2) Exploring to what extent people are willing to ‘conserve energy’ by using less of a product and/or accepting lower comfort levels. These two themes were partly captured in the title of a recent international Conference held in Oxford: Behave 2014 – Paradigm Shift: From Energy Efficiency to Energy Reduction through Social Change. Yet even at this Conference there was a prevalence of papers focused around the energy efficiency paradigm and the question: to what extent people should be nudged, persuaded or coerced into conserving energy? was not, in my view, adequately touched upon or debated. This is perhaps unsurprising, when considering that asking people not to aspire to high comfort levels may be unappealing for policy makers. In fact, many communication and public relations companies specialising in sustainability and climate change highlight the need for ‘positive messages’, avoiding gloomy pictures or end of the world scenarios, focusing instead on positive/happy stories and on what people can do (as opposed to what they should not do) – ideally also referring to additional benefits arising from saving energy. This is a very appealing notion, but also one with hidden complexities. The rebound effect is a fairly well-known potential side-effect of energy efficiency, where the financial savings arising from the new technology/service can incentivise greater use of the technology/service itself (e.g. greater indoor temperatures arising from home insulation), or lead to lower energy prices, which in turn can increase energy use. Whilst the question of whether rebound effects can altogether outweigh any savings arising from energy efficiency is being debated, clearly these effects should be minimised. This, however, can be difficult if the trade-offs between comfort and energy use are not adequately acknowledged. On the contrary, many energy saving interventions are ‘sold’ to the public on the basis of added benefits, such as saving money and greater thermal comfort – as in the case of home insulation measures. Inevitably, these approaches can embed expectations for higher thermal comfort, regardless of the fact that greater levels of comfort, whilst perhaps desirable, may in fact not be needed in some cases. The need to disambiguate the trade-offs between comfort and energy is apparent in the findings of a recent randomised controlled trial aiming to test whether tailored advice from a ‘trusted messenger’ on how to use heating controls can reduce energy consumption. The study, commissioned by the UK’s Department of Energy and Climate Change (DECC), found that the use of in-home advice or informative leaflets within social housing did not significantly

Repeatability and Reproducibility of &lt;I&gt;In Situ&lt;/I&gt; Measurements of Sound Reflection and Airborne Sound Insulation Index of Noise Barriers

In Europe, in situ measurements of sound reflection and airborne sound insulation of noise barriers are usually done according to CEN/TS 1793-5. This method has been improved substantially during the EU funded QUIESST collaborative project. Within the same framework, an inter-laboratory test has been carried out to assess the repeatability and reproducibility of the newly developed method when applied to real-life samples, including the effect of outdoor weather variability and sample ageing. This article presents the statistical analysis of the inter-laboratory test results, and the values of the repeatability and the reproducibility, both in one-third octave bands and for the single-number ratings. The estimated reproducibility values can be used as the extended measure of uncertainty at the 95% credibility level in compliance with the ISO GUM. The repeatability and reproducibility values associated with airborne sound insulation are also compared with the corresponding values for laboratory measurements in building acoustics and an acceptable agreement is found.

Uncertainty determination of in situ airborne sound insulation measurements

In building acoustics the measurement uncertainty of sound insulation measurements is traditionally either not reported or reported as stated in the corresponding standard ISO 12999–1:2014. Determination and application of measurement uncertainties in building acoustics—Part 1: Sound insulation (former ISO 140-2). An alternative procedure is presented in this paper, aiming at evaluating the need of performing individual uncertainty calculations and the effect of extending the frequency range used to calculate sound insulation single number quantities. A large set of in situ airborne sound insulation measurements is investigated following the ISO Guide to the Expression of Uncertainty in Measurement (GUM) both for DnT 1/3 octave bands values and for single number rating DnTA. Two alternative assessment frequency ranges (50/100–5000Hz) have been considered. The paper describes a methodology for uncertainty determination to emphasize that it is possible to determine such individual uncertainties following the ISO GUM approach to a certain extent and that each individual measurement needs a corresponding measurement uncertainty calculation. In addition, the results show that if the assessment frequency range is extended below 100Hz, the uncertainty of the single number quantity is increased.