Breathing Wall Research Articles

Digital Fiction and the Unnatural: Transmedial Narrative Theory, Method, and Analysis

Digital Fiction and the Unnatural: Transmedial Narrative Theory, Method, and Analysis

Determining the critical insulation thickness of breathing wall: Analytical model, key parameters, and design

Breathing wall (BW) based on air-permeable porous medium offers an alternative solution for utilizing the conductive heat loss of building envelope to preheat the infiltration ventilation airflow within porous medium. However, current studies neglect the influence of pressure drop within porous medium on the energy performance of BW, which may lead to an overestimation or non-optimal design. In this study, we proposed a framework to determine the critical insulation thickness of BW for minimizing its convective heat loss and pressure drop related energy loss. An analytical model was developed and validated to calculate the heat loss of BW under third-type boundary condition. Darcy's law was applied to estimate the pressure drop of infiltration airflow and its associated energy loss. Case studies were conducted to identify the critical insulation thickness of BW. The critical thickness of BW under different scenarios was investigated. The results demonstrate the existence of critical thickness, which yields the lowest overall heat loss of BW. A larger infiltration airflow rate or lower air permeability of porous medium will result in a downward trend of this critical thickness. The outcomes of this study can provide a design guideline of BW for maximizing its energy saving potential.

A numerical model to simulate the dynamic performance of Breathing Walls

A one-dimensional Finite Difference Model for Breathing Wall components under time dependent Dirichlet boundary conditions is presented. The algorithm undergoes a comprehensive validation against a dynamic analytical model, under either sinusoidal and generically periodic boundary conditions, adopting different airflow velocities and in relation to capacitive and resistive materials alternatively. It is found that the accurate prediction of the temperature profile inside the wall is influenced primarily by the timestep, whose optimal value can be identified through a preliminary frequency analysis of the boundary conditions. Moreover, for a better prediction of the surface heat flow density, and especially in insulating materials, refining the space grid below 1 mm is recommended, as well as the adoption of a 3-point numerical scheme. The numerical model is finally tested against experimental data on a porous concrete wall, showing that numerical errors may compare to other sources of uncertainties, regarding materials properties and boundary conditions.

Experimental validation of a steady periodic analytical model for Breathing Walls

The Breathing Wall behaviour under variable boundary conditions is described by an analytical model based on a one-dimensional porous domain crossed by air and subject to third type steady periodic boundary conditions. To the best of the authors’ knowledge, its experimental validation is not provided in literature.In this work, a new model is derived considering Dirichlet steady periodic boundary conditions. The model is experimentally validated testing a 1 m2 no-fines concrete sample in the Dual Air Vented Thermal Box apparatus, specially improved to replicate dynamic thermal conditions. The experiments show that increasing the air flow velocity across the Breathing Wall from 0 to 12 mm/s enhances thermal coupling between the two environments, namely reduces the wall thermal capacity, with a decrease in the penetration time from 4.3 h to 3 h.The model shows a very good agreement with experimental data when predicting temperature distribution across the domain, with error averages and standard deviations within the thermocouple accuracy after calibration, assumed to be 0.15 ∘C. The lesser yet good agreement concerning conduction heat flux density is explained in terms of accuracy in the measurement of the boundary conditions and critical issues in the heat flow measure itself (i.e. probe thermal resistance, thermal contact, emissivity mismatch).

Measuring a Breathing Wall's effectiveness and dynamic behaviour

Breathing Walls are building structures based on porous materials crossed by an airflow, which act both as building envelopes and ventilation system components. In climates where both heating and cooling are needed, a pro-flux configuration (heat and air mass both flowing in the same direction) might be alternated with a contra-flux configuration (heat and air mass flowing in opposite directions) during the year or even on a day. Understanding and modelling the Breathing Walls' stationary and dynamic behaviour is thus fundamental, in order to optimize their design and to fully exploit their energy-saving potential. In this experimental study, a small-scale no-fines concrete Breathing Wall was investigated. The steady-state contra-flux tests performed in a Dual Air-Vented Thermal Box laboratory apparatus were used to derive the heat recovery efficiency of the sample as a function of the cross airflow velocity. The effectiveness of this technology was then evaluated in a virtual case study. An optimal airflow velocity across the Breathing Wall was found, leading to energy savings between 9% and 14%. Dynamic tests were performed assuming a sinusoidal variation of the operative temperature on one side of the sample. They showed how airflow velocity affected the Breathing Wall inertia and dynamic behaviour.

Analytical modelling of Breathing Walls: experimental verification by means of the Dual Air Vented Thermal Box lab facility

Breathing Walls are air permeable envelope components based on porous materials. In contra-flux operation air flows opposite to conductive flux, while in pro-flux they have the same direction. The Breathing Wall behaves either as a ventilation heat exchanger or as an active insulation.In literature an analytical model describing steady state heat transfer across a Breathing Wall can be found. Since it lacks an exhaustive experimental validation, a facility developed at the Energy Department of Politecnico of Milano was used to investigate the thermo-physical behavior of a no-fines concrete based Breathing Wall in steady state Dirichlet conditions and contra-flux operation.

Experimental and numerical assessment of breathing walls performance for theimprovement of air quality and comfort indoors

The construction of airtight building envelopes within nearly Zero Energy Buildings is likely to generate thermo-hygrometric discomfort indoors, that needs to be managed with airconditioning and ventilation systems. In countertrend, some researches developed in northern Europe countries focused on the construction of “breathing” building envelopes that let in the air (passively or with mechanical devices) through dynamic thermal insulations able to preheat and filter it from possible pollutants. This study reports the results of experimental and analytical assessments of dynamic insulation systems, aimed to the design of a breathing wall system for the application in building renovation interventions.

The Breathing Wall (BRALL)—Triggering Life (in)animate Surfaces

This paper investigates the tactile possibilities of human interaction with synthetic biomorphic surfaces through an interdisciplinary collaboration between arts, materials science, mechanical, and electronics engineering. The authors created a breathing wall (BRALL) composed of nine silicone-based tiles that feel like flesh, breathe, emit sound, and respond to touch by pneumatic activation that is enabled by soft robotics technology. The authors believe combining a flesh-like material with soft motion and tactile responsiveness brings us a step closer to replicating/imitating organic life. The authors also question the potential of interacting with synthetic structures and what the social and cognitive implications of such exchanges could be.

Transport and Absorption of Anesthetic Vapors in a Mouth-Lung Model Extending to G9 Bronchioles

Background: The inhalation of anesthetic vapors into the lungs is a function of both the respiration and inhalant property. Factors which influence the alveolar concentration of anesthetics include breathing activities, airway morphology, anesthetic diffusivity, and wall absorption rate. Administered anesthetic levels could be significantly different from the alveolar level due to wall absorption loss and gas mixing in the airway. Objective: To assess the transport and absorption of inhaled anesthetics in an anatomically accurate respiratory airway geometry. Specifically aims include understanding the transport of inhaled vapors, quantifying the pulmonary dosage of administered anesthetics, and identifying factors that influence airway absorption losses. Methods: The geometry consisted of a CT-based mouth-throat (MT) model and a tracheobronchial (TB) model which extends to G9 bronchioles and consists of 115 outlets. Vapor transport and absorption were simulated using the Chemical Species model coupled with a user-defined vapor-absorption module. Results: Unlike previously assumed developed flows after G6, features of developing flows are still apparent in the G9 bronchioles in this study. Large variations of bronchiolar vapor concentrations were observed among the five lobes. Under quiet breathing conditions, vapor concentrations at the G9 outlets are 15 - 30% of the inhaled concentration level due to gas mixing and wall absorption. The delivered dose to the pulmonary region varies from 48% to 96%, depending on the vapor diffusivity and solubility. Vapor depletion due to wall absorption is significant (52%) for highly soluble anesthetics and is inconsequential for low solubility ones. Conclusion: A computer model was developed that implemented a wall absorption module in a realistic mouth-lung model extending to G9. This model provides the basis for future quantitative studies of the relationship between administered anesthetics and induced anesthetic level.

패시브환기외피의 통기 및 열성능에 관한 실험적 연구

ABSTRACT:In this study, 5 types of PVS(Passive ventilation system) units are made and expe-rimented its ventilation performance, thermal performance according to open rate and hole diameter of perforated aluminum plane. Results are as follows. 1) The ventilation performance increases approximately 50～70% according by the open rate of PVS increasing. Also, the ventilation performance increases about 2%～12% according by the hole diameter of PVS increasing. 2) In winter temperature/pressure condition(in：20℃, out：-2℃/△P：0.2～5.0Pa) the temperature of inflow air decreases according by the open rate of PVS increasing. Heat gain performance decreases 10.1%, 25.6% when open rate increases 3) In the same condition, Heat gain performance decreases 18.3%, 18.8% according by the hole diameter of PVS increasing.Keywords:Passive ventilation(패시브 환기), Building envelopes(외피), Breathing wall(숨쉬는 벽체), Ventilation performance(통기성능), Thermal performance(열성능), Natural ventilation (자연환기) †Corresponding author Tel.: +82-51-510-2355; fax: +82-51-512-8478 E-mail address: yoon@pusan.ac.kr

Evaluation of thermal conductivity in air permeable concrete for dynamic breathing wall construction

Abstract Air permeable concrete (APC) is potentially useful as a dynamic insulator. The dynamic function is achieved by passing air through the material in the direction of heat flow to facilitate heat recovery. An APC sample of 200 mm length with 60% cement filling of large voids (between 0.5 and 5 mm), was tested between 5 and 10 Pa differential pressures; permeabilities were 0.28–0.32 m2/Pa h, confirming its suitability as a dynamic insulator. To characterise properties it is necessary to determine the static thermal conductivity, i.e., no air flow. A one-dimensional heat flow model for predicting the effective thermal conductivity (λe) of APC is developed using as variables the fractions of voids, aggregate and cement paste comprising the material. Measured values of λe were 0.7–1.4 W/m K. A theoretical model predicts and further improves the performance and formulation of APC. The water/cement ratio (w/c) also controls the λe. Increasing w/c increases the volume of micropores, adding resistance to heat flow.

Modular breathing panels for energy efficient, healthy building construction

The paper presents the state-of-the-art and the science underlying a new generation of modular breathing wall systems, and their implementation in new and refurbishment building projects. Examples of how these new breathing wall systems are being implemented in the UK and in other countries will be briefly outlined.

Breath by breath: An interview with Kate Pullinger about “The Breathing Wall”

Breath by breath: An interview with Kate Pullinger about “The Breathing Wall”

Sound reproduction device working according to the bending wave principle

The invention concerns the embodiment of panel loudspeakers working according to the bending wave principle. Said loudspeakers are generally formed by at least one acoustic panel (11) and at least one driver (12), the driver (12) being connected to the acoustic panel (11). When such acoustic panels (11) are used for reproducing low frequency audio signals, the acoustic panels (11) must be arranged in sufficiently large sound walls in order to exclude the occurrence of an acoustic short circuit between the front part and the back part of the panel. Apart from being costly, only one side of the sound walls is actively used for sound generation as a result of the separation of both acoustic panels (11). Hence, the invention aims at providing a panel loudspeaker (10) that does not require any additional sound walls in order to exclude the occurrence of an acoustic short circuit while at the same time enabling full utilization of the surface of the acoustic panel (11) for sound generation, This is achieved by arranging two of the acoustic panels (11.1, 11.2) at a distance (A) in relation to each other, by providing elements (13) connecting both acoustic panels (11.1, 11.2) and by arranging the drivers (12) on the sides of the acoustic panels (11.1, 11.2) facing each other. Due to the fact that, once connected, both acoustic panels (11.1, 11.2) vibrate in opposite directions, they mimic the principle of a breathing sphere or wall.

炭化ワラ材料を用いた透気性壁体の適用手法に関する研究 : 実験住宅における壁体の熱・湿気特注

A breathing wall using rice straw charcoal was applied to the solar house, which had a floor heating and cooling system using outdoor air. In order to investigate the possibility of practical use of the wall, thermal and moisture characteristics of the wall were experimentally examined using the actual sized walls installed in the solar house, which was situated in suburban Tokyo. As a result of the outdoor measurement, it was found that high humidity condition in the walls did not last longer than a day from winter through summer. Moreover, in spite of high wind velocity condition in summer, the difference of temperature between the walls inflow-surface and the room showed less than 3K.

The pattern of breathing and chest wall movements at different levels of pressure support and PEEP

We previously found that optoelectronic plethysmography can be used to measure the chest wall volume and its compartments: rib cage and abdomen [1]. We evaluated the breathing pattern and the chest wall displacement during pressure support (PSV) in patients with acute respiratory failure. Nine intubated patients (age 57 ± 12 years, BMI 26 ± 5 kg/m2, PaO2/FiO2 293 ± 67) were studied first at four levels of PSV (5, 10, 15, 25 cmH2O) at 10 cmH2O of PEEP and then at three levels of PEEP (5, 10, 15 cmH2O) at 10 of PSV. We measured the breathing pattern, the ribcage contribution to tidal volume (RC/VT) and the inspiratory asynchrony (IA) [2]. IA was calculated as the area enclosed by the inspiratory portion of rib cage abdomen loop and the line connecting the commencement and the terminal of inspiration. Our results suggest that only the level of PSV affects the breathing pattern. Table 1

炭化ワラ材料の透気特性および熱的特性 : 環境調和型建築部材としての炭化ワラ材料を用いた「息をする壁体」の提案 その1

炭化ワラ材料の透気特性および熱的特性 : 環境調和型建築部材としての炭化ワラ材料を用いた「息をする壁体」の提案 その1

PASSIVE VENTILATION SYSTEM THAT INCORPORATES A PITCHED ROOF CONSTRUCTED OF BREATHING WALLS FOR USE IN A PASSIVE SOLAR HOUSE

This paper describes a natural ventilation system that incorporates a pitched roof constructed of Breathing Walls for use in a passive solar house. The Breathing Wall is expected to solve the inherent contradiction that exists for a building that is open to the outside air, in which a balance in the indoor air/moisture conditions is maintained, but energy efficiency is low. In other words, the use of Breathing Walls can provide a healthy and comfortable environment at higher energy efficiency in a passive solar house. In the present study, we experimentally evaluate the effects of roof pitch on the heat recovery capability and the occurrence of internal condensation within the Breathing Wall, using a simulation of the ventilation rate of a natural ventilation system. The effective opening area per unit area required to provide sufficient air change capability, i.e., 0.5 ACH, even for zero wind velocity, was determined to be 10 and 5 cm 2/m 2 for pitches of 26.5° (Pitch 1) and 45° (Pitch 2), respectively. Furthermore, at the maximum predicted wind velocity of 10 m/s for Pitch 1/2, even though the outdoor air temperature is 5°C, the temperature of the indoor-most air reaches 13.2/12.5°C, corresponding to a heat flux of ≈128/158 W/m 2. No internal condensation occurs, even at the maximum pressure differential, which corresponds to a wind velocity of 10 m/s across the wall of the Pitch 1/2 model, when a Breathing Wall having an opening area per unit area of 11.3 cm 2/m 2 was installed in the ventilation system.

The application of dynamic insulation in buildings

Dynamic insulation, a form of ‘Breathing Wall’ construction which allows the movement of air and moisture through the external walls of a building, was seen as one possible method for reducing building envelope heat losses and achieving high indoor air quality. A research investigation was conducted to provide a firm scientific understanding of dynamic insulation. An important outcome of the work will be the development of building envelope designs which effectively and economically employ dynamic insulation in cold climates. This paper presents some general conclusions, confirming that the energy saving produced by dynamic insulation alone is small relative to that obtained in conjunction with conventional air heat recovery methods.