Multi-room Buildings Research Articles

Enhancing energy-efficient building design: a multi-agent-assisted MOEA/D approach for multi-objective optimization

Energy-efficient building design is often challenged by multiple optimization problems due to contradictory objectives that are often hard to balance, so an effective optimization method should be thoroughly considered. Accordingly, a multi-objective evolutionary algorithm is then proposed. Firstly, the multi-agent auxiliary objective evolutionary algorithm for building energy efficiency model is established. According to model result analysis, the proposed algorithm runs fastest for 1640s with the average running time of 1710s in a single-room building, comparing to the least running time of 1680s for the multi-objective particle swarm optimization algorithm. In multi-room buildings, the proposed algorithm runs from 3350s to 3650s, with the average running time of 3500s. In conclusion, the model proposed in this study can comprehensively consider multiple objectives such as energy consumption, cost, comfort, etc. No matter in single-room or multi-room buildings, the model demonstrates superior performance and stability to realize comprehensive optimization of energy conservation design.

The Numerical Simulation Study of Pumping Airflow Driven by Wind Pressure for Single- and Multi-Room Buildings

Pumping airflow occurs in single-sided natural ventilation buildings when the openings are located on the leeward side; the direction of airflow through the building then changes periodicity. In order to propose a calculation method of the ventilation rates for single-room buildings and analyze the pumping ventilation for multi-room buildings, the CFD method with an SST k-ω turbulence model was used to conduct numerical simulation in this study, which is verified by other experimental results. Firstly, the qualitative and quantitative characteristics of pumping ventilation were investigated for a single-room building with two openings. The results show that the steady-state method underestimates the ventilation flow rates, and the unsteady-state method captures the microstructures of the flow better. Secondly, the vortex-shedding and indoor airflow oscillation frequencies were analyzed based on transient simulation for a single-room building. It was found that both of them increase with air speed. Then, the factors affecting ventilation flow rates were analyzed. A calculation method for dimensionless ventilation rates is proposed. Finally, the pumping ventilation for a multi-room building was numerically simulated. The ventilation rate for a middle room is greater than that for a corner room, and the ventilation rate for any room in a multi-room building is greater than the single-room building given the same room size and the same incoming wind speed. The findings of this paper are helpful for the design and evaluation of natural ventilation.

Global Transformer Architecture for Indoor Room Temperature Forecasting

A thorough regulation of building energy systems translates in relevant energy savings and in a better comfort for the occupants. Algorithms to predict the thermal state of a building on a certain time horizon with a good confidence are essential for the implementation of effective control systems. This work presents a global Transformer architecture for indoor temperature forecasting in multi-room buildings, aiming at optimizing energy consumption and reducing greenhouse gas emissions associated with HVAC systems. Recent advancements in deep learning have enabled the development of more sophisticated forecasting models compared to traditional feedback control systems. The proposed global Transformer architecture can be trained on the entire dataset encompassing all rooms, eliminating the need for multiple room-specific models, significantly improving predictive performance, and simplifying deployment and maintenance. Notably, this study is the first to apply a Transformer architecture for indoor temperature forecasting in multi-room buildings. The proposed approach provides a novel solution to enhance the accuracy and efficiency of temperature forecasting, serving as a valuable tool to optimize energy consumption and decrease greenhouse gas emissions in the building sector.

Size dependent infectivity of SARS-CoV-2 via respiratory droplets spread through central ventilation systems

Here we evaluate the transport of respiratory droplets that carry SARS-CoV-2 through central air handling systems in multiroom buildings. Respiratory droplet size modes arise from the bronchioles representing the lungs and lower respiratory tract, the larynx representing the upper respiratory tract including vocal cords, or the oral cavity. The size distribution of each mode remains largely conserved, although the magnitude of each droplet mode changes as infected individuals breathe, speak, sing, laugh, cough, and sneeze. Here we evaluate how each type of respiratory droplet transits through central ventilation systems and the implications thereof for infectivity of COVID-19. We find that while larger oral droplets can transmit through the air handling systems, their size and concentration are greatly reduced with but few oral droplets leaving the source room. In contrast, the smaller droplets that originate from the bronchioles and larynx are much more effective in transiting through the air handling system into connected rooms. This suggests that the ratio of lower respiratory or deep lung infections may increase relative to upper respiratory infections in rooms connected by central air handling systems. Also, increasing the temperature and humidity in the range considered after the droplets have achieved an “equilibrium” size reduces the probability of infection.

Three-Dimensional Object Detection with Deep Neural Networks for Automatic As-Built Reconstruction

AbstractAutomatic three-dimensional (3D) as-built reconstruction for non-Manhattan structures and multiroom buildings remains an industrywide challenge due to complex building environments and high...

Investigation of potential aerosol transmission and infectivity of SARS-CoV-2 through central ventilation systems

The COVID-19 pandemic has raised concern of viral spread within buildings. Although near-field transmission and infectious spread within individual rooms are well studied, the impact of aerosolized spread of SARS-CoV-2 via air handling systems within multiroom buildings remains unexplored. This study evaluates the concentrations and probabilities of infection for both building interior and exterior exposure sources using a well-mixed model in a multiroom building served by a central air handling system (without packaged terminal air conditioning). In particular, we compare the influence of filtration, air change rates, and the fraction of outdoor air. When the air supplied to the rooms comprises both outdoor air and recirculated air, we find filtration lowers the concentration and probability of infection the most in connected rooms. We find that increasing the air change rate removes virus from the source room faster but also increases the rate of exposure in connected rooms. Therefore, slower air change rates reduce infectivity in connected rooms at shorter durations. We further find that increasing the fraction of virus-free outdoor air is helpful, unless outdoor air is infective in which case pathogen exposure inside persists for hours after a short-term release. Increasing the outdoor air to 33% or the filter to MERV-13 decreases the infectivity in the connected rooms by 19% or 93% respectively, relative to a MERV-8 filter with 9% outdoor air based on 100 quanta/h of 5 μm droplets, a breathing rate of 0.48 m3/h, and the building dimensions and air handling system considered.

Experimental study of airflow and pollutant dispersion in cross-ventilated multi-room buildings: Effects of source location and ventilation path

Indoor air quality (IAQ) problem and associated health risks, determined by the indoor air pollutant, are of great concern in modern society. This paper presents a detailed experimental study of pollutant dispersion and airflow characteristics in a multi-room building under cross ventilation condition. A series of experiments were conducted in a scaled multi-room chamber which represents a slap-shaped building. A wind wall system was developed to simulate the cross-ventilated environment. The windows and doors were used as cross ventilation openings, enabling three ventilation path test scenarios. Tracer gas technique was employed to reveal the pollutant dispersion features in the chamber under different conditions. Both the air velocities and tracer gas concentrations at selected key positions in the chamber were measured. The mean concentration values were analyzed to investigate the influence of source location and ventilation path on the pollutant dispersion. This study shows that the pollutant dispersion and airflow characteristics can be strongly influenced by the source location and the ventilation path under approximately the same inflow conditions, and the differences were quantitatively presented. The results give useful insights into the airflow pollutant dispersion process in cross-ventilated multi-room buildings and provide a valuable database for the validation of CFD simulations.

Cluster analysis of microclimate data to optimize the number of sensors for the assessment of indoor environment within museums.

For the first time, the cluster analysis (k-means) has been applied on long time series of temperature and relative humidity measurements to identify the thermo-hygrometric features in a museum. Based on ASHRAE (2011) classification, 84% of time all rooms in the Napoleonic Museum in Rome (case study) were found in the class of control B. This result was obtained by analyzing all recorded data in 10 rooms of the museum as well as using the cluster aggregation. The use of objective-oriented methodology allows to achieve an acceptable knowledge of the microclimate in case of multi-room buildings, reducing computations with large amounts of collected data and time-consuming in redundant elaborations. The cluster analysis enables to reduce the number of the sensors in microclimate monitoring programs within museums, provided that the representativeness of the instrument location is known, and professional conservators have assessed that the artifacts are well preserved.

Modeling and Simulation of Multi-Room Buildings

Buildings are one of the largest energy consumers in the world which accounts for nearly 40% of the total global energy consumption. In the countries where cold climate conditions predominate, space heating is the key contributor to the increased energy consumption. Today there is a growing trend to use Building Energy Management Systems (BEMS) to control the energy consumption of buildings in an ecient manner. BEMS require a good heating model of the building to be integrated for better control purposes. This article refers to the development of dierent types of physics based buillding heating models, regarding single-zone, multi-oor and multi-room buildings. They address the propriety of each model in building heating control concerning the prediction accuracy and the prediction time. These models are veried for a residential building having three oors. According to the results, the multi-oor model is recognized to have the best qualications obliged as a model for control.

Improving Quality of Service of Femto Cell Using Optimum Location Identification

To enhance the throughput and Quality of Service (QoS) of indoor users, Femto cells became the best solution. The placement of a femtocell is always a challenging task due to its interference constraints with other cells. If the base stations has limited number of Femto-cells, then there is need to focus much on interference constraints. In the dense countries like India, there is a need to install more number of Femto-cells to get the proper throughput. But, the limiting factor here is frequency and interference management. This paper explained the interference management issues and hand over issues. This paper proposed method of optimal placement of Femto cell to increase the QoS in dense environment where macro-cell holds many number of Femto cells. This solution made an assumption that the interference effect was considerably strong when compared to Noise. Hence, we have not considered Noise parameter in the analysis. It was shown that the optimal placement has better throughput when compared to blind placement. Two cases were considered as blind placements and their throughput was analyzed with respect to optimal placement. The proposed method was tested in both single and multi-room buildings. Finally, it was observed that the gain of 50% was increased with respect to large buildings with many rooms. Index Terms—Femto cell, Quality of Service, throughput and interference.

Uncertainty of Tenability Times in Multiroom Building Fires

Fire risk for building occupants is determined by the time required for safe egress and the time at which untenable conditions develop in building rooms or on the egress routes. In the present study, the CFAST zone model is applied to the simulation of fire development and smoke propagation in multiroom buildings, with the aim of studying the sensitivity of predicted tenability times and quantification of the uncertainties due to variability of the scenario parameters. The building geometries considered are (i) a single room with a door and a window, (ii) three rooms connected by a long corridor, and (iii) two-level configuration with two rooms on the lower floor connected by a vertical vent to a room on the upper floor. Sensitivity indices of the tenability times due to high temperature and smoke obscuration are analyzed. Distribution functions of the tenability times are presented and compared for different building rooms.

An experimental study of wind-driven cross ventilation in partitioned buildings

This study uses wind tunnel experiments to investigate wind-driven cross ventilation in partitioned buildings. The discharge coefficients of internal opening under various flow conditions were determined by a fan technique. It was found that the internal discharge coefficient is dependent on the internal porosity, but independent of external porosity, and opening location. Based on the experimental results, a predictive model for internal pressure and ventilation rate of multi-room buildings was developed and verified. This model also revealed that the ventilation rate increases as the internal porosity increases, and that the maximum ventilation rate occurs when the windward and leeward opening areas are equal. Because internal partitions reduce the difference between external and internal pressure, the ventilation rate of partitioned buildings is always smaller than that of buildings without partition. Furthermore, this study provides a quantitative scheme to regulate the ventilation rate of partitioned buildings by controlling the opening areas of windward, leeward and internal openings.

Comparison of airflow and particulate matter transport in multi-room buildings for different natural ventilation patterns

This study numerically investigates airflow characteristics and particulate matter (PM) transport in multi-room buildings for different natural ventilation patterns with the same air change rate. Four typical natural ventilation patterns (full-open, pass-through, right short-circuit and left short-circuit), representing the ratios of the outlet-to-inlet opening size ranging from 1.67 to 0.17, are considered to study multi-room airflow characteristics. A measured indoor PM 10 profile in Taipei Metropolis is input into the above four ventilation patterns as the initial condition of the PM size distribution. The time variation of indoor PM 10/PM 2.5/PM 1 concentrations in each room for various ventilation patterns is next investigated. The effect of ventilation pattern on particle removal mechanism is emphasized. The results show that although the air change rate of the building is the same, airflow characteristics and PM transport behaviors are quite different for various ventilation patterns. The removal efficiencies of PM 10 for the four ventilation patterns are all found to be much better than those of PM 2.5 and PM 1. Particle escape is the major mechanism to remove PM for rooms with double-sided ventilation, whereas particle deposition is important for single-sided ventilation rooms.

Numerical investigation of airflow pattern and particulate matter transport in naturally ventilated multi-room buildings

This study reports on a numerical investigation of transport behavior of indoor airflow and size-dependent particulate matter (PM) in multi-room buildings. An indoor size-dependent PM transport approach, combining the Eulerian large-eddy simulation of turbulent flow with the Lagrangian particle trajectory tracking, was developed to investigate indoor airflow pattern and PM1/PM2.5/PM10 removal efficiency in naturally ventilated multi-room buildings. A displacement ventilation with a measured indoor PM10 profile in Taipei Metropolis as the initial condition was carried out to characterize spatial and temporal variations of indoor PM1/PM2.5/PM10 removal behavior. The effects of indoor airflow pattern on particle transport mechanisms, e.g., deposition, suspension, migration and escape, were analyzed. Two comparison scenarios, which considered the effects of no indoor partition and different air change rate, respectively, were also conducted. In comparison with the effectiveness of PM1/PM2.5/PM10 removal, the simulated results showed that coarse particles were easier to be removed out of the building than fine particles. Natural ventilation was not an effective way to remove fine particles such as PM1 and PM2.5 in a multi-room building. Indoor partitions can impede 12% of the mean streamwise velocities and significantly increase 30-50% turbulence intensities. However, indoor partitions increased particle deposition and decreased particle escape. As a result of the two opposite particle removal mechanisms, i.e., deposition and escape, the impact of indoor partitions on PM1/PM2.5/PM10 removal behavior was not as significant as the results of airflow velocities. This work developed a computational fluid dynamics technique to investigate indoor airflow patterns and PM1/PM2.5/PM10 removal ability in ventilated multi-room buildings. The results of this paper can help to identify adequate PM1/PM2.5/PM10 cleaning procedure and provide useful size-dependent PM control strategy in multi-room buildings.

Proposal of a Method to Calculate Room Temperature in Multi-Room Buildings by an Improved Matrix Computing and its Application to Evaluate CO2 Reduction Utilizing High Light-Reflective and High Heat-Emissive Paint

In this paper, we proposed a procedure for calculation of room temperature in multi-room building using the backward-difference method. Based on this procedure and using our simulation program, we evaluated CO2 reduction by installating high light-reflective and high heat-emissive paint in buildings. Heat balance equations on each heat point in each room or wall in the building were deduced from one-dimensional heat-conduction equation and converted to the matrix equation. We improved matrix computing and developed a different procedure from conventional methods. Because this procedure is simple, we consider that this is applicable to estimation of most building’s technologies. As its application, the effects of high light-reflective and high heat-emissive paint was evaluated. Although the paint increases heating load, it can reduce cooling load. We thus conclude that the paint is effective for CO2 reduction.

区画間の火災拡大を考慮した建物燃焼性状予測モデル

A model for predicting buming behavior in multi-room buildings is developed with emphasis on room-to-room fire spread. In the model, building fire is considered as an ensemble of multiple room fires, and a one-zone method is applied to simulate the fire behavior of component rooms. The spread of fire is described as the ignition of combustible due to heat transfer from (1) hot gas of adjacent compartment involved in fire, and (2) external flame ejected from downstairs compartment. A model of bum-through of partitioning walls/doors, which may result the increase in the mass and heat transport, is also introduced. The fire behaviors in a building composed of eleven rooms ale simulated. The results are compared with the full scale experimental data in a literature, showing reasonable agreement after some adjustments of the unknown bum-through temperatures T_<BT>-and bum-through rate coefficientχ_<BT> of wall/door materials.

A Physically-Based Model for Urban Fire Spread

An attempt is made to develop a physically-based model for simulating urban fire spread. In the model, urban fire is regarded as an ensemble of multiple building fires. The model consists of two sub-models, i.e. the model to predict the building fire behavior under the exposure of heating from other building fires and the model to predict the thermal environment caused by building fires. The building fire model is based on single zone method, applying control volumes to compartments in a building. When the external heating, whether it is from the same building or from other buildings, exceeds the critical heat flux, the fire load in the compartment ignites and burns. For the thermal environment model, thermal radiation and fire-induced plume are considered as the factors of building-to-building fire spread. The model is applied to a fictitious urban district where 49 multi-room buildings are arrayed in a simple configuration.

Earthfast (Pieux en Terre) structures at old mobile

Recent investigations at Old Mobile have included excavation of the first earthfast pieux en terre buildings discovered at this early French colonial site. These small one-room structures may have been barracks for soldiers garrisoned at Fort Louis. Previously excavated structures, interpreted as domestic dwellings, are multi-room buildings of poteaux sur sole (post-on-sill), a more substantial construction method. Differences in floor plan, size, construction method, and associated artifact assemblages reflect differences in structure function and occupation.

Strategies for solving the air flow—Thermal problem in multiroom buildings

Iterative and direct methods for solving the coupled problem of heat and mass transfers in buildings are presented and compared. Numerical problems often trouble the resolution of this problem and a choice between different strategies can be a way to overcome instabilities of calculus and runningtime difficulties. The state of the zones of air is represented as a function of temperature and pressure. The iterative method consists of separating the problem into two sub-sets, the first being a function of temperature and the other a function of pressure. The direct method simultaneously carries out the resolution of the original set. Two simulation codes were developed based on the ‘coupling method’, which is a method of solving the thermal problem by splitting it into levels of coupling. The direct option needs more computational effort, but is easier to run by non-experts. In contrast, the iterative method is better adapted to the connection of different programs. Simulation results are presented, and the performances of the two strategies are compared and discussed.

Prediction of the Dynamic Thermal Characteristics of Multi-room Buildings by Applying the Environmental Temperature Concept : Part 1-Improvements of the Accuracy of Numerical Analysis and Modelling the Heat Flow at Internal Surfaces

Prediction of the Dynamic Thermal Characteristics of Multi-room Buildings by Applying the Environmental Temperature Concept : Part 1-Improvements of the Accuracy of Numerical Analysis and Modelling the Heat Flow at Internal Surfaces