Abstract: The aims of this research are to discuss acoustical building performance for natural ventilation systems and to predict traffic noise level for inhabitants residing in urban settlements. Natural ventilation systems use outdoor air to improve the quality of indoor environments and can reduce energy consumption. However, natural ventilation systems create an acoustical problem. For example, if windows are opened for natural ventilation, outdoor traffic noise can disrupt people working and sleeping in the building. In this study, a new method that combines an algorithm to predict traffic noise levels (calculation of road traffic noise) with the Federal Highway Administration Traffic Noise Model’s vehicle noise spectra correctly predicts the properties of noise propagation and attenuation through openings in urban environments, as well as outdoor sound propagation, sound reduction index, and indoor sound transmission. In order to develop this method, various traffic noise prediction methods to calculate sound attenuation during propagation outdoors based on International Organization for Standardization 9613 were analyzed. This study also describes the noise attenuation effect from surrounding elements, such as building envelope, location of openings, opening ratio, and indoor boundary conditions. The results of the simulations indicate that the integrated noise evaluation method can successfully predict the acoustic performance of natural ventilation systems in urban areas.
Permalink: https://doi.org/10.1080/23744731.2016.1262708

Abstract: Air-conditioning systems account for nearly one-third of the energy consumption in tropical buildings. In summer, mechanical cooling systems become a must especially in office buildings to keep the indoor environment comfort. In this study, a normal office room is designed to evaluate a novel cooling system based on a hot and humid climate. This novel cooling system is considered to serve such climate, which integrates radiant cooling panel, decentralized ventilation, and an Airbox convector. The Airbox convector is designed to deal with condensation risk and provide additional cooling output. In order to evaluate this novel system, it is compared with conventional all-air system and normal radiant system with decentralized ventilation regarding to the system capacity, energy consumption and thermal comfort. Results show that this novel system is adaptable to such climates and capable to reduce the condensation risk and overall cooling energy consumption.
Permalink: https://doi.org/10.1016/j.proeng.2017.10.367

Abstract: This study aims at understanding the phenomenon of shock reflection over different geometries of concave surfaces. Double cylindrical concave wedges are generated computationally by changing different geometrical parameters like the radii of the cylindrical surfaces and the initial wedge angle of the two surfaces. The study focuses on the effects of the change of the geometry of the concave surfaces and the incident shock wave Mach numbers on the overall behavior of shock wave reflections. The simulations are done for four different incident shock wave Mach numbers. The investigation of the geometrical effect reveals a number of interesting wave features starting from the early stage of the shock interaction and transition from transitioned regular reflection (TRR) over the first concave surface followed by complex shock reflections over the second concave surface. Two new behaviors of shock reflection are found over the second concave surface, which appear to depend on the initial wedge angle of the concave surfaces. First, an additional shock wave appears when the TRR over the first concave surface meets the incident shock wave on the second concave surface and eventually merges with the reflected wave. Second, the additional shock wave falls behind the incident one and penetrates the reflected wave over the second concave surface. Also, it was found that the difference between the transition wedge angles over the two concave surfaces increased as the incident shock wave Mach number increased. These findings indicate that the shock wave does have a characteristic to retain its memory.
Permalink: https://doi.org/10.1007/978-3-319-46213-4_100

Abstract: This study explores the bacterial composition of floor dust in different rooms of a kindergarten over the course of a year, utilizing DNA sequencing techniques to analyze microbial diversity. The research aims to understand how built environments influence microbial exposure, particularly for young children who are more likely to come into contact with floor dust. The findings show variation in bacterial communities across different rooms and highlight the significance of this exposure in shaping children’s developing microbiota, with implications for designing healthier built environments.

Abstract: Bio-based building materials offer a wide range of outlooks, from traditional rustic to modern design products. Recent development in the science of materials significantly improves their functional performance. However, when considering the use of bio-materials in outdoor environments, materials will deteriorate due to processes like weathering, oxidation, biodegradation, wear, and decay. Consequentially, biomaterials may lose visual appeal, leading to a perceived need for replacement even if the material is far from reaching functional failure. Visual assessment is the most direct method for evaluation of the aesthetic appearance of materials. However, it possesses a high degree of subjectivity when performed by an untrained person. On the contrary, measurement of surface properties with dedicated sensors provides objective values that might be related to the current state of the material in use. Recent developments in field of optics and electronics opens a new possibility to perform measurements in-situ. Colour-, gloss-, or spectro-photo-meters allow non-destructive measurements without particular sample preparation. Since all of the above techniques provide complementary information, the multi-sensor approach is more frequently suggested for applied research. The material state can be assessed regularly during service life. In this case, such measurement turns into monitoring. The paper illustrates examples of assessment and monitoring of biomaterials’ degradation due to weathering. Direct implementation of various sensors is demonstrated. A proposal for the approach of combining data provided by various sensing techniques with data mining is also presented.
Permalink: https://doi.org/10.2495/SDP170461

Abstract: This paper reports the numerical analysis of shock wave diffraction over a convex sharp splitter geometry, focusing on the mechanism of the shock diffraction and the longtime behavior of shock–vortex dynamics. The flow evolution with shock–vortex dynamics for incident shock Mach number, Ms=1.59, is found to be in excellent agreement with the previous experimental results. We use a recent entropy-generation-based artificial viscosity (AV) method in conjunction with a high-order explicit discontinuous spectral element method (DSEM) to resolve these complex interactions. The AV is coupled with a shock sensor switch to attain optimal dissipations. Simulations capture the essential wave diffraction, transverse wave interaction with the deforming and growing primary vortex, and weaker secondary vortices arising from the Kelvin–Helmholtz instability. A quantification of the artificial dissipation of the numerical scheme is made by comparing the components of the kinetic energy dissipation rate and the pressure dilatation term. A new detailed transient flow analysis is also presented to address the shock dynamics, shock–vortex interaction, and the evolution of the flow topology with the probability density functions of various parameters of the enstrophy transport equation and the invariants of the velocity gradient tensor. The analysis reveals the mechanism of unwinding of vortices and its link with the divergence of the Lamb vector. A positive correlation is found between enstrophy and the imaginary part of the eigenvalues. Real parts of the two eigenvalues are associated with high dilatation shock regions and the outer edges of the vortices, respectively.
Permalink: https://doi.org/10.1007/s00193-017-0767-z

Abstract: Unmistakably, buildings retrofitting brings the possibilities to reduce energy use and greenhouse gas emissions. However, selecting specific retrofit strategies is complex and requires careful planning. There are already various technics of buildings retrofitting towards nearly zero energy level. Therefore, the focal point in this paper is the review of relevant solutions and the effect of their corresponding consequences on building energy efficiency as well as recommending renewable energy technologies. Further investigation on the feasibility of adopting these technics for cold climates requires thorough studies to be carried out through experiments or numerical simulations.
Permalink: https://doi.org/10.1016/j.egypro.2017.09.534

Abstract: Air infiltration holds a central role in building energy consumption and is associated to several building physics phenomena. Air infiltration in buildings due to wind-induced pressure is a complex process, strongly influenced by the turbulent nature of wind. This extended summary highlights the findings of a series of studies with focus on unsteady wind and its impact on air exchangesin buildings. The focus is on wind gustiness and its relation to air infiltration under natural conditions. Wind spectrum analysis shows that high-frequency wind gusts provide important information, while only considering mean wind speed and direction are not adequate to predict air exchanges in buildings. The impact of gustiness becomes greater for evenly distributed leakages between windward (upstream) and leeward (downstream) façade. Infiltration measurements under unsteady wind can vary significantly from results estimated based on pressurization measurements. In addition, wind gustiness is responsible for large pressure differences across leakages, thus it can affect the results of leakage numbers and the uncertainty of such measurements especially when the measurement point is low.

Abstract: This work presents an analysis on heat transfer process occurred in the Trombe wall system with a new channel design in Yazd (Iran) on the coldest and warmest days of winter. The primary objective was to investigate the impact of heat transfer types on the temperature variation of the Trombe wall back and absorber throughout the day. For this reason, the variations of Rayleigh number, convective heat transfer coefficient, and the rate of convection, conduction, and radiation heat transfer exchanged with the Trombe wall have been studied. The analysis of Rayleigh number variations for the channel inside revealed that there is a noticeable decrease in the early hours expressing a discernible decrease in the temperature difference between the absorber and the channel space. At night time, the absorber and channel temperatures drop approximately to the same value. Furthermore, the role of conduction transfer is more sensible than that of convection in the early and late hours. However, the convection dominates at the midday. It should be noted that due to new channel design, the radiation heat transfer rate is maximum in the early and late hours. The heat transfer is more significant on the coldest day because of higher temperature difference between the different parts of the Trombe wall system.
Permalink: https://doi.org/10.1016/j.energy.2017.06.066

Abstract: [Norwegian] I prosjektet BEST VENT er det sett nærmere på dagens formulering i Klimaveiledning 444 om full døgnkontinuerlig ventilasjon i ett år for nybygg og rehabiliterte bygg. Det har skjedd to viktig endringer siden anbefalingen kom for rundt 30 år siden: i) strengere krav til bruk av lavemitterende materialer og ii) behovsstyring av luftmengdene. Denne litteraturstudien har hatt som mål å foreslå en revidert formulering basert på en gjennomgang av studier som belyser emisjoner i tidlig avgassingsfase, hvilken effekt økt ventilasjon har på avgassingshastighet og hvor lang tid det tar før nivåene er på et akseptabelt nivå. I skoler og kontorbygg er det stor variasjon i ventilasjonsbehovet, og man kan oppnå store besparelser ved å senke luftmengdene i rom som ikke er i bruk. De gjennomgåtte publikasjonene gir ikke grunnlag for å anta at minimumsventilasjon utenom bygningens driftstid større enn 2,5 m3/(h*m2 ) er nødvendig for at primæremisjoner fra materialer skal avta raskt. Dette bør opprettholdes i 6 måneder etter ferdig overflatebehandling. Det er behov for videre arbeid for å avklare hvilke luftmengder som er optimale for å øke emisjonsraten samtidig som konsentrasjonene tynnes ut i tilstrekkelig grad, og hvordan dette kan løses på best mulig måte med behovsstyrt ventilasjon.

Abstract: Ground source heat pumps are being common in western countries in order to reduce the primary energy consumption and the corresponding greenhouse gas emissions associated with heating and cooling of buildings. In this paper, a parametric study was conducted to investigate the performance of a ground source heat pump configured with a vertical ground loop. Mathematical models were developed for the different components of the heat pump, and EES was used to analyse the performance of the heat pump considering the influence of the ground’s depth, mass flow rates of brine, types of working fluids, and the dead state condition of the environment. The results revealed that the working fluids performed differently for the various operating parameters, and importantly selection of refrigerants as a working fluid for the ground source heat pump needs through thermodynamics analysis.
Permalink: https://doi.org/10.1016/j.egypro.2017.03.267

Abstract: The use of wood in built environments has been increasing during the last decades, and more focus has been set on the influence of wood surfaces on indoor environments on the objective and subjective measures of human well-being. In addition, the moisture buffer capacity of hygroscopic materials, such as wood, has been under investigation in order to quantify the impact of wooden surfaces on energy savings in buildings. The current study presents the results of wood surfaces and indoor air temperatures as well as indoor air relative humidity measured in two solid timber test houses. The findings reveal a substantial effect on wood surface temperature under fluctuating indoor relative humidity due to the latent heat of sorption of water vapors. The results were compared with hygrothermal numerical simulations, showing good agreement and the validated numerical model was used in order to quantify the energy performance in a bathroom when the latent heat of sorption is exploited. The combination of wood with a well-controlled HVAC system in rooms with moisture production shows significant potential for indirect energy savings by adjusting the indoor temperature and exploiting the increase of surface temperature in the hygroscopic structure. Furthermore, the emissions of volatile organic compounds from pine wood were studied in laboratory facilities, with focus on the variations of emissions due to diurnal fluctuations in air humidity. Human participants were exposed in a large test chamber to a concealed source of volatile organic compound emissions in the form of fresh pine wood, while the actual exposure reached air levels of monoterpenes up to 18 mg/m3 during the intervention situation. Perceptions of air quality and mucosal irritation effects were reported in a standard questionnaire during this double-blind test with no irritation effects reported.
Permalink: https://doi.org/10.1080/23744731.2017.1288503

Abstract: Phase change materials (PCM) have the potential to enhance the energy performance and thermal comfort of buildings. The main purpose of this work is to investigate the thermal performance and indoor climate benefits of bio-PCM integrated in an office cubicle. The study is based on experimental work, where air temperature of the 15 m2 test room, as well as the surface temperature of the PCM and the walls, floor and ceiling were recorded. Different scenarios were considered, including PCM used as a suspended ceiling without supporting ceiling plates, as well as PCM covered with ceiling plates. The preliminary result shows that a significant cooling effect could be achieved when using 17 m2 of uncovered PCM directly exposed to the occupied zone. The PCM could therefore, to a certain extent, reduce the need of mechanical cooling and thus save costs for installation, energy use and maintenance.
Permalink: https://doi.org/10.1016/j.egypro.2017.03.223

Abstract: Wood as hygroscopic material has the capacity to absorb moisture and thus to moderate the indoor relative humidity (RH) in a building, resulting in lower ventilation demand. In addition, when moisture migrates in hygroscopic structures energy is released through latent heat phenomena. The diurnal variation of moisture content in wood hold a potential for contributing in the buildings energy balance. This study presents the theoretical energy savings in low energy buildings with interior wooden surfaces under different moisture protocols indoors. The requirements of the Norwegian Building Regulations (TEK10) are followed regarding the U-values of the envelope components. A hygrothermal simulation tool is employed to estimate the potential diurnal variations of moisture content in the wood structure. The latent heat released and absorbed is mathematically calculated for a reference building. The results show the potential of hygroscopic structures to save thermal energy by means of heat of sorption and to reduce the conductive heat losses through opaque building elements. The limitations of the phenomena are also discussed.
Permalink: https://doi.org/10.1016/j.proenv.2017.03.102