Assessing noise and overheating in dwellings: Aligning acoustic and thermal models for partially open windows

Traditionally, the internal environmental quality (IEQ) aspects of acoustic and thermal comfort have been considered and designed separately. However, where occupants rely on opening or closing windows to achieve these dimensions, they are not independent in use. To consider both simultaneously, it is crucial to have a simple model of a partially open window that can predict both acoustic and thermal conditions internally. CIBSE TM59 defines the assessment method for adaptive thermal comfort. In the thermal model the ventilation performance of open windows can be described with an "Equivalent Area" (EA). We propose to use the EA to calculate the facade sound insulation based on a simple assessment according to Annex D of ISO 12354-3, i.e. as a facade element with an area of EA and zero sound insulation. This study presents field measurements of sound insulation according to ISO 16283-3 with road traffic sound sources, to evaluate the acoustic uncertainty of using the EA to calculate internal sound levels. Results show encouraging correlation between measurements of element-normalized level difference, Dn,e,w + Ctr and calculations based on the EA. This model is considered adequate for acoustic design purposes, and represents a significant simplification compared with previous proposals.

In-situ investigation of the acoustical performance in collective social dwellings

Mass timber is increasingly being employed in constructing low- and mid-rise buildings. One of the primary reasons for using mass timber structures is their sustainability and ability to reduce environmental consequences in the building sector. One criticism of these structures is their lower subjective sound insulation quality. Therefore, acoustic treatments should be considered. However, acoustic solutions do not necessarily contribute to lower environmental impacts or improved thermal insulation performance. This paper discusses a design methodology that incorporates the development of a sound insulation prediction tool (using an artificial neural networks approach), life cycle assessment analysis, and thermal insulation study. A total of 112 sound insulation measurements (in one-third octave bands from 50 to 5000 Hz) are utilized to develop the network model and are also used for the LCA and thermal insulation study. They are lab-based measurements and are performed on 45 various CLT- and ribbed CLT-based assemblies. The acoustic model demonstrates satisfactory results with 1 dB differences in the prediction of airborne and impact sound indices (Rw and Ln,w). An acoustic sensitivity study and a statistical analysis are then conducted to validate the model’s results. Additionally, an LCA analysis is performed on the floor assemblies to calculate their environmental footprints. LCA categories are plotted against the acoustic performance of floors. No correlations are found, and the results emphasize that a wide range of sound insulation can be achieved with similar environmental impacts. Within each acoustic performance tier, the LCA results can be optimized for a floor assembly by selecting appropriate materials. The thermal insulation of floors is then calculated. Overall, a strong positive correlation is found between the total thermal resistance and heat loss against acoustic performance. Designers should be cognizant of the trade-offs between acoustic, thermal insulation, and environmental performance when choosing assemblies with favorable environmental impacts relative to acoustic and thermal insulation ratios.

Investigation of the sound insulation and natural ventilation performance of a metamaterial-based open window

Housing complex residents in urban areas are not only confronted with typical noise sources, but also everyday life sounds, e.g., in the yards. Therefore, they might benefit from the increasing interest in soundscape design and acoustic comfort improvement. Three laboratory experiments (with repeated-measures complete block designs) are reported here, in which effects of several variables on short-term acoustic comfort were investigated. A virtual reference inner yard in the ODEON software environment was systematically modified by absorbers on building facades, whereby single-channel recordings were spatialized for a 2D playback in laboratory. Facade absorption was found, generally, to increase acoustic comfort. Too much absorption, however, was not found to be helpful. In the absence of any absorbers on the facade, absorbing balcony ceilings tended to improve acoustic comfort, however, non-significantly. Pleasant and unpleasant sounds were associated with comfort and discomfort, accordingly. This should encourage architects and acousticians to create comfortable inner yard sound environments, where pleasant and unpleasant sound occurrence probabilities are designed to be high and low, respectively. Furthermore, significant differences were observed between acoustic comfort at distinct observer positions, which could be exploited when designing inner yards.

Lightweight wooden-framed constructions have steadily increased their market share in Sweden during the last two decades. Achieving acoustic and vibration comfort in wooden-based buildings is, however, still a challenging task. Wood is high in both strength and stiffness in relation to its weight, but its variability has repercussions on how sound propagates, this triggering sound insulation problems. Even if buildings comply with present-to-day regulations, complaints amid residents often arise due to low frequency noise, as it is outside the scope of the standards (where no analyses are performed below 50 Hz). In this investigation, laboratory acoustic sound insulation measurements carried out on a facade element according to the current standards, are intended to be reproduced and calibrated by means of the finite element method. In doing so, the first steps of a numerical predictive tool mimicking the real specimen, from 0 to 100 Hz, are presented. This will enable further research about phenomena occurring in the far low end of the frequency range, which is believed to be the cause of most nuisances reported by residents. Reliable predictive tools for addressing acoustic issues during the design phase avoid additional costs of building test prototypes and ensure a better acoustic performance.

The complicated nature of indoor environmental quality (IEQ) (thermal, visual, acoustic comfort, etc.) dictates a multi-fold approach for desirable IEQ levels to be achieved. The improvement of building shells’ thermal performance, imposed by the constantly revised buildings’ energy performance regulations, does not necessarily guarantee the upgrade of all IEQ-related aspects, such as the construction’s acoustic quality, as most of the commonly used insulation materials are characterized by their low acoustic performance properties. From this perspective the SUstainable PReconstructed Innovative Module (SU.PR.I.M.) research project investigates a new, innovative preconstructed building module with advanced characteristics, which can, among other features, provide a high quality of acoustic performance in the indoor space. The module consists of two reinforced concrete vertical panels, between which the load bearing steel profiles are positioned. In the cavity and at the exterior surface of the panel there is a layer of thermal insulation. For the scope of the analysis, different external finishing surfaces are considered, including cladding with slate and brick, and different cavity insulation materials are examined. The addition of Phase Change Materials (PCM) in different mix proportions in the interior concrete panel is also examined. For the calculation of the sound insulation performance of the building module the INSUL 9.0 software is used. The results were validated through an experimental measurement in the laboratory in order to test the consistency of the values obtained. The results indicate that the examined preconstructed module can cover the sound insulation national regulation’s performance limits, but the implementation of such panels in building constructions should be carefully considered in case of lower frequency noise environments.

In commercial buildings, the total consumption of central air conditioning accounts for about 40%–50%. However, at present, the initial design value of building Heating Ventilation and Air Conditioning (HVAC) is usually far greater than the actual refrigeration value of refrigeration demand, which will lead to great energy consumption waste. Moreover, the operation of HVAC affects the thermal comfort of users, so it is necessary to establish a thermal model for the scene to control. The thermal model describes the temperature of the scene in different environments. So it is very important to design a thermal model to calculate the scene in real time. Because the flow of people, the opening of windows, the ventilation of the scene and other parameters influence the change of thermal state in the scene environment, these parameters are complicated to model. Human disturbance will lead to the instability of the state of the scene environment. The inconsistency of its thermal model will lead to energy allocation tracking strategies in different regions. To solve this problem, We propose a thermal model for building thermal comfort using a multimodal analysis framework. This paper analyzes multiple temperature and humidity sensors and area image by multimodal combination and processes the image and sensor data by combining CNN and LSTM. Our results show that when the thermal model analyzed by this method is deployed in a building in the south of China, the MSE accuracy of the local effect of temperature field prediction reaches 99%, and its AMAX reaches 94%, so the running stability of the model in the scene is high. In addition, the research shows that the thermal model analysis framework can make the Internet of Things (IoT) in buildings more intelligent, and it can be combined with this thermal model to improve human comfort, make it easier to deploy in each hot zone, and have a better overall energy-saving effect.

Room acoustical parameters have frequently been used to evaluate or predict the acoustical performance in rooms. For housing complexes in urban areas with high population density, it is important to improve acoustic performance not solely indoors, but outdoors as well; for example on the balconies or in the yards. This paper investigates to what extent classic room acoustical parameters would be able to predict the perceived acoustic comfort in outdoor spaces (i.e., courtyards) of virtual housing complexes. Individual and combined effects of a series of independent variables (such as facade absorption, sound source, and observer position) on short-term acoustic comfort were investigated in three laboratory experiments. ODEON software was used for virtual inner yard simulation, whereby 2D spatialization was carried out for a playback over five loudspeakers. Moderate facade absorption was found to increase acoustic comfort. Relatively pleasant and relatively unpleasant sounds were associated with comfort and discomfort, respectively. Lower acoustic comfort ratings were observed at receiver positions with high sound pressure levels and/or strong flutter echoes. A further analysis of the results is carried out here with respect to the room acoustical parameters and their ability to predict the acoustic comfort ratings. Speech transmission index (STI), definition (D50), clarity of speech (C50) and music (C80), early decay time (EDT), and lateral energy fraction (LF80) were found to be significantly correlated with acoustic comfort. They were found to be significant predictors of acoustic comfort in a series of linear mixed-effect models. Furthermore, linear mixed-effect models were established with the A-weighted equivalent continuous sound level, LAeq, as a significant predictor of acoustic comfort.

Despite the emergence of acoustic metamaterials with superior sound absorption and transmission loss, their adoption for building sound insulation has been limited. Sound insulation design in buildings is still informed by the acoustic performance of conventional materials, where the mass law contradicts light weighting when it comes to acoustic design. In any case buildings close to noisy environments such as motorways, railway lines and airports still suffer from significant low frequency noise pollution. Although the limited working bandwidth of acoustic metamaterials is a major issue limiting its application, combining meta-units that interact at various frequencies alongside multi-layer conventional solutions can deliver superior sound insulation in buildings. The review put forwards acoustic metamaterials, specifically emphasising superior sound absorption and transmission/insertion loss as critical properties for effective building sound insulation. The paper reveals a variety of acoustic metamaterials that can be adopted to compliment conventional sound insulation approaches for acoustically efficient building design. The performance of these metamaterials is then explained through their characteristic negative mass density, bulk modulus or repeating or locally resonating microstructure. The review is also extended to air transparent acoustic metamaterials that can be used for sound insulation of building ventilation. Lastly the prospects and challenges regarding the adoption of acoustic metamaterials in building insulation are also discussed. Overall, tuneable, and multifunctional acoustic metamaterials when thoughtfully integrated to building sound insulation can lead to significant acoustic comfort, space-saving and light-weighting.

Minimizing the energy consumed by heating, ventilation, and air conditioning (HVAC) systems of residential buildings without impacting occupants’ comfort has been highlighted as an important artificial intelligence (AI) challenge. Typically, approaches that seek to address this challenge use a model that captures the thermal dynamics within a building, also referred to as a thermal model. Among thermal models, gray-box models are a popular choice for modeling the thermal dynamics of buildings. They combine knowledge of the physical structure of a building with various data-driven inputs and are accurate estimators of the state (internal temperature). However, existing gray-box models require a detailed specification of all the physical elements that can affect the thermal dynamics of a building a priori. This limits their applicability, particularly in residential buildings, where additional dynamics can be induced by human activities such as cooking, which contributes additional heat, or opening of windows, which leads to additional leakage of heat. Since the incidence of these additional dynamics is rarely known, their combined effects cannot readily be accommodated within existing models. To overcome this limitation and improve the general applicability of gray-box models, we introduce a novel model, which we refer to as a latent force thermal model of the thermal dynamics of a building, or LFM-TM. Our model is derived from an existing gray-box thermal model, which is augmented with an extra term referred to as the learned residual. This term is capable of modeling the effect of any a priori unknown additional dynamic, which, if not captured, appears as a structure in a thermal model’s residual (the error induced by the model). More importantly, the learned residual can also capture the effects of physical elements such as a building’s envelope or the lags in a heating system, leading to a significant reduction in complexity compared to existing models. To evaluate the performance of LFM-TM, we apply it to two independent data sources. The first is an established dataset, referred to as the FlexHouse data, which was previously used for evaluating the efficacy of existing gray-box models [Bacher and Madsen 2011]. The second dataset consists of heating data logged within homes located on the University of Southampton campus, which were specifically instrumented to collect data for our thermal modeling experiments. On both datasets, we show that LFM-TM outperforms existing models in its ability to accurately fit the observed data, generate accurate day-ahead internal temperature predictions, and explain a large amount of the variability in the future observations. This, along with the fact that we also use a corresponding efficient sequential inference scheme for LFM-TM, makes it an ideal candidate for model-based predictive control, where having accurate online predictions of internal temperatures is essential for high-quality solutions.

Sound insulation with partially open windows has had growing attention in recent years. In Denmark, this is primarily caused by the Danish Environmental Protection Agency's guideline from 2007 "Noise from roads", which introduces noise limits with open windows (opening area of 0.35 m2) for situations with a high traffic noise level. The sound insulation of traditional windows in open position have been measured in both the laboratory and external environment, and for certain setups too different results have been observed. To investigate the reasons behind the discrepancies, the traditionally reverberant source room of laboratory measurements was modified to a semi-anechoic room to remove reflections from unwanted reflections from room surfaces and to imitate the external environment during field measurements. Four different window types were tested as part of the research projects "Optimized measurement method for sound reduction of partially open windows part 1 and 2" (MetÅV and MetÅV2) in collaboration with four Danish window manufacturers. The primary focus of the project is to explore alternative laboratory methods to the traditional diffuse field method by studying reference cases from field measurements and taking into consideration different sound source positions and window geometry. This paper describes the results so far.

Façade sound insulation regulations are typically focused on closed windows. However, many people prefer open windows for ventilation purposes, or simply because of the psychological effect of having an open window. As such it is important to be able to correctly quantify the sound insulation, also with open windows. The international standard ISO 16283-3 describes a field method for test of façade sound insulation of facades or façade elements, e.g. a window, which is further explained in the scope: "The element methods aim to estimate the sound reduction index of a façade element, for example, a window. The most accurate element method uses a loudspeaker as an artificial sound source. Other less accurate element methods use available traffic noise". However, the standard is probably primarily meant for closed windows, and not for open windows. The applicability of ISO 16283-3 for open windows is therefore under investigation for such conditions which are included in an additional Danish environmental noise guideline. Generally, it can be concluded that the traffic noise method is applicable, but care should be taken by using the loudspeaker method for partially open windows, since the results depend highly on the window opening position compared to the loudspeaker position.

Development Classification Scheme for Evaluation Dwellings Sound Insulation Performance in Lithuania

Acoustic comfort is one of the main factors of a man’s comfortable existence in the residence places. Over the past century, a lot of experience has been accumulated in isolating rooms from noise using enclosing structures, but the acoustic regime is deteriorating due to the constant increase in the power and number of noise sources in localities and buildings themselves. Therefore, acoustic comfort is not always provided in the premises even with satisfactory sound insulation of enclosing, as experimental studies have shown. In addition, humanity strives to build structures with the lowest material and labor costs. All this makes us look for more effective solutions for sound insulation and sound absorption. A sound-proof panel made of acoustic resonators ZIPAR is a plate of sound-absorbing material consisting of an outer sealed, sound-absorbing and sound-insulating layers. The air cavities of the sound-absorbing layer are made of upper parts-resonators, in the form of truncated cones, which cross-section decreases in the direction of the outer layer, and the cavities in the sound-absorbing layer have a cylindrical shape; these are the lower parts-deflectors. The data obtained as a result of tests are intended for use as a reference material in the design and installation of noise protection premises, both in new construction and in the reconstruction and minor repairs of existing buildings.