bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Metamaterial Inspired 2ndIteration Koch Fractal Antenna for Wi-Fi, WLAN, C band and X band Wireless Communications
Authors: Ramalakshmi Gudla , Mallikarjuna Rao P
Published: December 2021

The rapid advancements in wireless technology desires compact, miniaturized, multiband and ultra wideband antennas. Fractal antennas have been proved as a source for fulfilling these demands. In this paper a 2ndorder Koch fractal antenna of size 29.6 × 35.7mm2designed on FR4-epoxy substrate material of dielectric constant (ɛr) 4.4 with a height of 1.6mm. This antenna is named as ANTENNA-1. To increase this antenna’s performance a meta material unit cell has been placed on the ground plane to serve multi band applications and is named as ANTENNA-2, which is the proposed antenna in this paper. The simulations have been carried out for both the antennas using ANSYS HFSS tool over the frequency sweep of (1-12GHz). The simulation results of proposed antenna producing 7 frequency bands which serves Wi-Fi, WLAN, C-band, and X band wireless communications. The simulation results like return loss, VSWR values have a good matching with the measured return loss, VSWR results of the fabricated antenna
Impact of Hello Intervals in AODV in FANET
Authors: Saini Hemant Kumar , Jain Kusumlata
Published: December 2021

Business and classified activity of UAV is changing various bionetwork. To perceive risky issue and investigate research zones, our precise content assessment suggests the critical issue like protection, reception and sanctuary are progressively supplanted by operational contemplations incorporating connection by and blow on other airspace clients. Ongoing episodes show that unlimited robot use can incur issues on other airspace clients like air terminals and crisis administrations. Our audit of current administrative methodologies shows a requirement for additional approach and oversight answer to both run quick and efficient ova utilization development, and work with advancement (for example intraurban bundle conveyance), with execution of the planned engineering is approved utilizing three boundaries, to be specific throughput, parcel conveyance proportion (PDR in various UAVs. The outcomes are contrasted and existing conventions show the adequacy of the work regarding throughput rate.
Development of Textual Analysis using Machine Learning to Improve the Sentiment Classification
Authors: Rajpoot Abha Kiran , Nand Parma , Abidi Ali Imam
Published: December 2021

Rapid development in Internet and the increase in online information, the technology demanded for intelligently classifying the textual data has become significant role in Information Retrieval Process. Based on given query in the search box, the response from the internet has made open to the public. Thus, the scope of text mining is being explored by several researchers. Sentiment Analysis is one of the most popular process for analysing user opinions and feelings, and since, online communication has become the fast ever growing medium for expressing thoughts, therefore, there have been development in text classification to improve sentiment analysis. In this paper, some of the prior works on sentiment analysis and the advancements in text classification have been discussed.
Design and Development of Pipe-inspection robot with vision 360°
Authors: Karthik CH , Sreedharan Pramod
Published: December 2021

A pipe is a most commonly used product in the daily operations of industrial plants. Boiler pipes and inner ribs reduce pollution, allowing industrial plants to be both environmentally friendly and economically efficient. However, if these pipes are damaged, it will cause a huge problem for humans and ecological imbalances. Therefore, an inside inspection of a pipe is most necessary, regular duty being conducted by a surveyor of the plant. Pipe inspection includes checking for cracks, defects, leaks, corrosion and blockages in a region. However, an individual cannot do this inspection due to life-risk impact, and there is a necessity for human intelligence. This proposed robot design helps inspect a portion of the building in less time than the entire vision. In addition, the view can be recorded and easily the damaged or blocked portions of the pipe.
Effect of di-methyl carbonate as additive and exhaust gas recirculation on the performance and emission parameters of diesel engine using diesel-biodiesel blends as fuel
Authors: Chandravanshi A , Pandey S , Malviya R K , Paikra A S
Published: December 2021

The Current situation of petroleum products pressurizes the world to shift towards green fuels. Dimethyl carbonate (DMC) could be considered as high oxygenated, green additive. Adding DMC in biodiesel increases the quality of combustion, hence reducing emissions with improved thermal efficiency. In the present study, DMC has been blended with biodiesel along with 10% Exhaust Gas Recirculation (EGR) and then performance and emission analysis was done. Results show higher Brake Thermal efficiency with 5% DMC in the biodiesel-diesel blend as compared to biodiesel, but lower than that with diesel. Brake Specific Energy Consumption increases with the increase in DMC in the fuel blend at medium and higher loads, which limits the use of DMC in higher content (10%, 15%). Carbon Mono-oxide and Hydrocarbon emissions reduce with lower content of DMC (5%) at a higher load. There are slight increases in Carbon Di-Oxide at all loads, under the safe limit. The emission of Oxides of Nitrogen (NOx) decreases slightly and this decrease increases with EGR. Higher content of EGR adversely affects the performance and emission characteristics except for NOx and smoke emission. A large decrease in smoke was noted with DMC as an additive in biodiesel due to improved combustion.
Investigation of Efficient Hole Injection Layer for Enhancement of Opto-Electrical Properties of an Organic Light Emitting Diode
Authors: Jain Neha , Singh Vikas , Prajapati Vivek
Published: December 2021

A multilayer Organic Light Emitting Diode (OLED) has been simulated and analysed for the investigation of an efficient Hole Injection Layer (HIL). Study includes the simulation of different devices which comprises of the different materials as HIL. Three devices have been simulated and their characteristics have been extracted to compare the electrical and optical properties of the OLEDs. It has been found that the device with HAT-CN as HIL has achieved the highest value of the current at the mentioned applied voltage and hence the current density. There is drastic enhancement in the current density of the device when an HIL is inserted in comparison to when it is not used in the OLED. Also, there is an approximate enhancement of around 20% in the device performance when HIL is changed from MoO3 to HAT-CN. The device without any HIL included has the highest electric field at the given voltage. Optical characteristics of the device includes Electroluminescence Intensity with respect to the varying wavelength and it has been observed that OLED achieved the maximum light intensity at an approximate wavelength of around 320 nm.
Question Answering Systems for Covid-19
Authors: Gupta Poonam , Garg Ruchi , Kaur Amandeep
Published: December 2021

In the present scenario COVID-19 pandemic has ruined the entire world. This situation motivates the researchers to resolve the query raised by the people around the world in an efficient manner. However, less number of resources available in order to gain the information and knowledge about COVID-19 arises a need to evaluate the existing Question Answering (QA) systems on COVID-19. In this paper, we compare the various QA systems available in order to answer the questions raised by the people like doctors, medical researchers etc. related to corona virus. QA systems process the queries submitted in natural language to find the best relevant answer among all the candidate answers for the COVID-19 related questions. These systems utilize the text mining and information retrieval on COVID-19 literature. This paper describes the survey of QA systems-CovidQA, CAiRE (Center for Artificial Intelligence Research)-COVID system, CO-search semantic search engine, COVIDASK, RECORD (Research Engine for COVID Open Research Dataset) available for COVID-19. All these QA systems are also compared in terms of their significant parameters-like Precision at rank 1 (P@1), Recall at rank 3(R@3), Mean Reciprocal Rank(MRR), F1-Score, Exact Match(EM), Mean Average Precision, Score metric etc.; on which efficiency of these systems relies.
Design and Simulation of Hybrid Solar PV-Fuel-Cell-Battery System to supply in the Nit Kurukshetra Campus and its effect on the Environment using Homer Software
Authors: kumar Alok , Vadhera Shelly
Published: December 2021

The main objective of this paper is to design a hybrid power system for continuous power supply in the institute campus nit Kurukshetra in an economical way to replace the external grid power system. In this paper solar photovoltaic Fuel cell battery hybrid system has been studied. Costing, sizing, optimization, and simulation were done using the software homer pro. The Levelized Cost of electricity (COE) is Rs. 11.12 per KW is obtained and the system is based on renewable energy sources so it sustainably generates electricity.
A simplified SVPWM method for cascaded multilevel inverters
Authors: Matale Nishant , Thakre Mohan , Shriwastava Rakesh
Published: December 2021

A highly popular alternative in medium voltage and high-power applications is multilevel converters because of their superior performance over conventional two-level converters. The most commonly used control methods in the case of multilevel inverters are sine pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. Among these two control strategies, SVPWM has superior performance over SPWM in terms of DC bus voltage utilization along with a reduction in total harmonic distortion (THD) of line voltages. The classical SVPWM method has various drawbacks such as computational complexity for identifying the location of reference voltage vector, sector identification, region identification, memory requirement to store lookup tables for switching vectors. The novel simplified SVPWM technique is presented for cascaded H-Bridge multilevel inverter (CHBMLI) in this paper. This simplified SVPWM method has overcome the drawbacks of the classical SVPWM method. This new technique has been implemented into a five-level CHBMLI to evaluate performance and also to compare with the SPWM method. The simulation has been performed in MATLAB software.
Hygrothermal performance of hemp lime concrete embedded with phase change materials for buildings
Authors: Omeme Ada A.M. , Tran Le A. D. , Toifane H. , Tittelein P. , Zalewski L. , Antczak E. , Douzane O. , Langlet T.
Published: December 2021

The use of biobased materials in building construction allows the reduction of fossil resource use and energy consumption. Among biobased materials, hemp lime concrete has been investigated in many studies highlighting its capacity to regulate interior relative humidity and its high insulation capacity. In order to design high-performance biobased concretes, a new hemp lime concrete combining the hygric regulation capacity of hemp lime concrete with the thermal regulation performance of phase change material was developed. This article focuses on the thermal and hygric performance of the new hemp lime concretes incorporating micro-capsulated phase change material (PCM) (named HL-PCM). Three hemp lime concretes that differ from formulation were developed and investigated. The thermal properties, moisture buffer values and its impact on interior relative humidity variation have been presented. Thanks to experimental works and numerical simulations, the results obtained showed that the thermal conductivity remain low, the heat capacity and thermal inertia increase considerably for hemp concrete with PCM, while the moisture buffering capacity remains excellent. Finally, numerical results showed that the used of hemp lime concrete (with and without PCM) reduce indoor relative humidity variation and improve indoor hygrothermal comfort.
Identifying the critical orientation of wood-frame walls in assessing moisture risks using hygrothermal simulation
Authors: Aggarwal Chetan , Defo Maurice , Ge Hua , Lacasse Michael A
Published: December 2021

Hygrothermal simulations can be used as a reliable tool in analysing moisture performance. For an efficient analysis, it is important to appropriately select the wall orientation in the simulations. ASHRAE 160 recommends to using orientation with highest amount of annual wind-driven rain (WDR) and the orientation with the least annual solar radiation. The objective of this work was to identify the orientation which leads to the worst moisture performance of different wall assemblies under historical climate in different Canadian cities. Four cardinal orientations (North, East, South, and West) and orientation receiving the highest amount of annual WDR (Default) were tested in this study. The simulations were carried out assuming three scenarios of moisture loads for four different wood-frame (2×6 wood stud) wall systems that differ by their claddings: brick, fibreboard, stucco, and vinyl. With an assumption of no WDR, north facing wall always leads to the worst moisture performance. In the presence of WDR, with and without water source, default orientation leads to the worst moisture performance with few exceptions. As default orientation was based on total sum of WDR, it sometimes may not lead to worst performance and hence hourly distribution of WDR should be taken into consideration.
Development of moisture reference years for assessing long-term mould growth risk of wood-frame building envelopes
Authors: Wang Lin , Defo Maurice , Gaur Abhishek , Lacasse Michael A
Published: December 2021

A moisture reference year (MRY) is generally used to assess the durability, or long-term performance of building envelopes within a long climatological time period, e.g. a 31 year timeframe. The intent of this paper is to develop a set of moisture reference years that can be used to assess risk to the formation of mould growth in wood-frame buildings over the long-term. The set of moisture reference years have been developed based on 15 realizations of 31-year climate data. Replicated Latin Hypercube Sampling is applied to select 15 sub-realizations with 7 representative years having different levels of moisture index (MI) from each realization. Thereafter, hygrothermal simulations are performed for a brick veneer clad wood-frame wall assembly using the 15 sub-realizations; that sub-realization which produces the highest value of maximum mould growth index over 7-year period is selected as the MRY. The selection process is then implemented for all 15 realizations of the 31-years of data sets, from which 15 sets of 7-year long MRYs are selected to represent the original 15 realizations. It is shown that the 15 sets of 7-year long MRYs can produce the same value of maximum mould growth index as well as the uncertainty as compared to the original 15 realizations having a 31-year climate data set.
Hygrothermal performance of internally insulated masonry walls with embedded wooden beam heads: a field study on the impact of hydrophobisation
Authors: Vereecken E , Roels S
Published: December 2021

Internal insulation remains often the only option to thermally upgrade massive masonry. Unfortunately, internal insulation can significantly change the wall’s hygrothermal performance, resulting in a higher risk on frost damage, wood rot of embedded beam heads, etc. The application of hydrophobisation is often put forward as a potential measure to avoid moisture problems, though more research on the impact of hydrophobisation is still required. Thereto, the current paper presents the results of a field study on the hygrothermal performance of internally insulated masonry with embedded wooden beam heads, exposed to wind-driven rain. Both a vapour open capillary active and a vapour tight insulation system are studied. Mainly the moisture conditions near the back of the wooden beam head are found to be influenced by hydrophobisation, which lowers the relative humidity. Closer to the masonry’s interior surface, the choice of the insulation system also influences the results. In case of a well-applied hydrophobisation, overall, the vapour tight system shows a better performance than the capillary active vapour open system. An exception to this is found for the first months after applying the hydrophobisation and the insulation system, where a longer drying period is needed in case of the vapour tight system.
Investigation of phase change materials (PCMs) on the heat transfer performance of building systems
Authors: Zhou Hongxia , Fransson Åke , Olofsson Thomas
Published: December 2021

The energy use of building systems contributes to a large percentage of total energy consumption, which requires consideration. Solutions of improvement to save energy are crucial. Phase change materials have been proved to be good candidates to be used in building envelopes for energy save. In this paper, an extended Explicit Finite Element Method (ex-FEM), which has been previously introduced and improved, is taken for simulation of temperatures and heat transfer in simplified multilayer wall constructions, consisting of PCM and insulation. The method has been validated against experimental data measured in a so-called Hot-Box. Temperature data are measured at different positions in a number of simplified multilayer walls. Our results show a reasonable good agreement between the simulations and the experiments, at both heating and cooling considering the temperature hysteresis effect in the PCM. The temperature stabilization ability of the PCM is clear, in both the simulations and the experiments, and particularly in the data when the transition range of the PCM is fully activated and matching the temperature variation in the wall at that particular PCM position. Our ex-FEM tool has here been proved to be able to predict the thermal performance of simplified wall constructions of multiple layers with PCMs incorporated.
Status assessment of buildings using existing data and identifying gaps in data from performance indicators
Authors: Mandinec Jan , Johansson Pär
Published: December 2021

In past decades, several performance indicators have been developed allowing to objectively assess current status or predict failures of material, components and other factors like moisture safety. However, each performance indicator requires its unique sets of data, which are often difficult to obtain. It is therefore of interest whether a combination of several indicators is applicable in older buildings which often lack readily available documentation. The aim of this study is to identify data gaps preventing the use of indicators and to ascertain whether missing data can be filled by combining visual inspections and non-destructive testing. The first part of the paper summarizes known building envelope related indicators and arrange them into three groups: general, hygrothermal and service life performance indicators. The second part is a case study where the applicability of selected performance indicators is tested against an in-house database consisting information about 610 buildings in Gothenburg. It was found that the use of performance indicators is limited as the gaps in the available data are present for all types of performance indicators. The material composition of buildings envelope was identified as the most substantial gap. This limited the use of hygrothermal performance indicators in 58.5% of the buildings.
Determining the impact of sensor orientation on moisture content measurements in eastern white pine
Authors: Daouk B , Baldwin C , Cruickshank C A
Published: December 2021

As buildings become more airtight and insulated, the movement and accumulation of moisture within building envelopes become paramount in determining its resiliency. Current methods for quantifying the moisture content (MC) of wood species involve the measurement of electrical resistance between two installed electrodes and the use of existing empirical correlations to evaluate the MC. However, these correlations do not adequately consider the impact of sensor orientation within wall assemblies. The objective of this paper is to determine the impact of MC readings within a wood sample due to sensor orientation. A total of 126 eastern white pine samples were tested with electrodes placed along the grain of the wood (longitudinal), across the grain of the wood (tangential), and in a diamond pattern, using six different fasteners as electrodes. The samples were placed in a controlled environmental chamber until steady state was achieved at approximately 18% MC. Electrical resistances of the samples were measured in both directions at temperatures ranging from -10°C to 40°C. It was found that the tangential-to-longitudinal resistance ratio is 1.1-1.35 depending on the electrode type.
Stochastic simulation of rain intrusion through small defects due to water rivulet overpressure. Introducing a driving rain leakage potential
Authors: Hagentoft C.-E. , Olsson L.
Published: December 2021

There is a need of upgrading the old building stock with respect to the thermal insulation of the building envelope and specifically the façades. There are several systems on the market, and some are quite new and innovative. To bring down the cost some of the systems many are based on prefabricated moisture tight insulated units. This means that in case there is moisture tight barrier on the interior side, two moisture tight barriers surround the wall structure. The leakage of driving rain into the structure then represents a major threat to the durability of these systems. This paper investigates the pressure build up in water rivulets running down a façade acting together with the wind pressure. A driving rain leakage potential is introduced. Using real weather data years and Monte Carlo Simulations, the mean and standard deviation of the annual leakage through small hole is estimated. The examples show that the leakage can reach a level 0-0.5 liter/year for a hole with a diameter of 1-2 mm, and 0.5-3 liter/year for a diameter of 3-4 mm.
Moisture related challenges in the Greenlandic building sector – results from a survey
Authors: de Place Hansen E J
Published: December 2021

The building industry is booming in the larger cities of Greenland; there is a need for housing, and the building stock is in urgent need of renovation, mainly due to the combination of extreme weather conditions and the lack of tradition to maintain buildings. The harsh climate with short summers and long periods of cold weather combined with occasionally high wind speed and precipitation makes it difficult to prevent moisture during the construction phase, causing high drying costs. These challenges highlight the need for guidelines on how to handle moisture especially in the construction phase, both at renovation or when erecting new buildings. To prepare the guidelines, a survey was carried out aimed at building professionals in Greenland. Focus was on identifying construction work challenged by the conditions in Greenland including geography and seasons. The feedback gave an overview on the main challenges and what kind of solutions that do or do not work, showing that handling of moisture in the construction phase is not the only problem. Further, the survey gave feedback on challenges related to specific technical solutions, e.g. crawl spaces, and what kind of information is missing in relation to moisture-safe construction in Greenland. As key-points, focus should be on project design, improved competences, handling of building materials and components at the building site, and explainable guidelines for specific solutions and building types.
Hygrothermal simulations of timber-framed walls with air leakages
Authors: Laukkarinen A , Jokela T , Moisio T , Vinha J
Published: December 2021

Air leakages can create substantial excess moisture loads into envelope structures and degrade their hygrothermal performance. Multiple previous research projects have studied the behaviour and modelling of air leakages in building physics applications, but it is still quite rare to see air leakages being considered in practical building design simulations. The purpose of this paper is to present the selection of input parameters for air leakage simulations, utilisation of a factorial design to manage simulation cases and the results for a timber-frame wall with and without air leakages. According to the results, the air permeability of mineral wool and the air pressure difference over the envelope were the two most important factors for the dry air mass flow through the structure, as opposed to gap width and leakage route. An ideally airtight structure had a better hygrothermal performance compared to leaky structure. However, when leakages were present, the exact yearly average air flow rate in the range 70…420 dm3/(m2h) did not have a strong correlation to the performance indicators. For the other studied variables, the existence of a 50 mm thick mineral wool insulation on the exterior side of the gypsum board wind barrier and the impacts from climate change had the biggest effect on the moisture performance of the structure.
Numerical And Experimental Study Of A Supply Air Wall Based On Integrated Insulation Clay Hollow Blocks
Authors: Bouvenot JB , Egg M
Published: December 2021

Integrated insulation clay hollow blocks is an interesting constructive system in the context of Near Zero Energy Buildings and building energy efficiency. Their simple modification into supply air wall can increase their thermal performance without great effort. This paper deals with the creation of an original supply air wall or window test bench and with the numerical and experimental study of a supply air wall (or ventilated wall) based on modified modern integrated insulation clay hollow blocks where large cavities (about 4 cm) are filled by mineral wool. In some cavities, mineral wool is removed to create a flow pattern, which aims to recover heat losses from inside and solar energy from outside. At first, a 3D CFD numerical model is presented to assess the energy performance of a 1 m2 sample of ventilated wall. Then, an experimental test bench, based on a modified guarded hot box simulating solar effects and airflows between the two chambers, is carried out to assess the real performances. A comparison between these two studies allows validating the results which show a good correlation in terms of temperature difference gains between outdoor temperature and pre-heated temperature going up to a maximum of 14 K for only 1 m2 of wall and for a volume flow rate of 4 m3/h (4,5 K for 32 m3/h).
A novel concept for energy-efficient floor heating systems with minimal hot water return temperatures
Authors: Smith Kevin Michael , Hu Nan , Østergaard Dorte Skaarup , Svendsen Svend
Published: December 2021

The study proposed and investigated a new concept for hydronic floor heating in dwellings with the aim of reducing hot water temperatures toward a more robust and energy efficient operation. Modern heating systems often rely on low return temperatures to improve operation efficiencies through reduced heat losses from return pipes, greater utilisation of condensation heat from boiler flue gases or from the increased COP of heat pumps. Our study investigated the potential of using an apartment heating substation (or ‘flat station’) to supply space heating through two mixing loops using hot water supply temperatures of 30°C to bathrooms and 24°C to all non-bathrooms. The concept sought to minimise hot water supply temperatures to utilise a self-regulating effect while ensuring low return temperatures. In the first iteration of the concept, the high-temperature return water from the bathrooms was cascaded to the non-bathrooms to heat these rooms and provide further cooling of the hot water. The calculated energy-weighted return temperature under this original concept was 25.6 °C for the example case of a new energy-efficient apartment building. However, there was limited potential to utilise the cascaded coupling, so considering the complexity of its configuration and controls, the authors simplified the proposed concept to two mixing loops without a cascaded coupling. The calculated return temperature with the updated concept was 25.7 °C. The control of the floor heating included some aspect of self-regulation because the heat transfer strongly depended on the indoor temperature. Based on the results of this preliminary investigation, the concept may provide a robust and energy-efficient option for configuring floor-heating systems in situations that rely on low hot-water return temperatures.
A simple method for validating a simulation model of a radiant ceiling panel with thermal energy storage
Authors: Gallardo Andres , Berardi Umberto
Published: December 2021

This paper focuses on validating a simulation model of a radiant ceiling panel (RCP) incorporating phase change materials (PCM) for heating and cooling applications in buildings. The development of an RCP with thermal energy storage capacity aims to encourage high thermal mass radiant systems in existing buildings to replace the traditional all-air HVAC system. First, a heat flow meter (HFM) is used to perform enthalpy measurements at a product scale (macro-encapsulated PCM). Then, a small test chamber is constructed to measure the dynamic thermal performance of an RCP with PCM under well-known and realistic boundary conditions. A known thermal resistance is used to establish a realistic heat transfer coefficient between room air (represented by the temperature of a temperature-controlled metal plate) and ceiling. The results show that HFM enthalpy measurements of products incorporating PCM are within ± 2% of manufacturers’ data. Additionally, results indicate that a test chamber can be used for validating a dynamic simulation model of the RCP with PCM installed in a room. The proposed method can be helpful during the system optimization phase, as many conditions and sample configurations can be tested without spending too much time or money on test rooms or real building monitoring.
Laboratory tests of a prototypical user-centric radiant cooling solution
Authors: Teufl H , Schuss M , Mahdavi A
Published: December 2021

Radiant cooling systems are being increasingly promoted because of their energy efficient operation as well as their potential to improve occupants’ thermal comfort due to a draft-free cooling process. This paper focuses on a specific radiant cooling approach, which was introduced in previous contributions. This approach involves the positioning of relatively small-sized vertical radiant panels in the close proximity to occupants. Furthermore, the panels incorporate drainage systems or collection elements to accommodate, if needed, water vapour condensation. Consequently, the surface temperature of the radiant panels does not need to stay above the dew point temperature. We present the outcome of a preliminary experimental investigation of such a personal radiant cooling system. In this context, prototypical radiant panels were installed in a laboratory and multiple experiments were conducted. The uniformity level of the panels’ surface temperature distribution was documented. Moreover, near-panel air flow velocities were measured at several positions. Likewise, the formation of condensed water on panels was observed for different panel surface temperatures, room temperatures, and room humidity levels. The results of the preliminary laboratory investigation do not point to any risk of draft or turbulence discomfort.
Electrochromic window integration in adaptive building envelopes in different climates: a genetic optimization of switchable glazing parameters to reduce energy consumptions in office buildings
Authors: Carlucci F , Cannavale A , Fiorito F
Published: December 2021

During last decades, many efforts have been made to address challenges regarding building energy consumption. A particularly interesting and effective field of development in the building domain is represented by responsive technologies applied to transparent envelopes. Among these technologies, the electrochromic (EC) glazing is one of the most developed solutions thanks to its capability to dynamically modulate daylight and thermal radiation, simply applying a controlled external voltage. The aim of this study is to provide a methodology to analyse smart responsive technologies and optimize the properties of an ideal switchable glazing to find the best configuration for a medium office in different climatic zones. The genetic optimization considers a 5-elements genome, constituted of the following genes: i) solar heat gain coefficient in bleached (SHGCB) and ii) coloured state (SHGCC), iii) visible light transmittance in bleached (VLTB) and iv) coloured state (VLTC) and v) thermal transmittance (U). Moreover, different European cities were selected as representative of different climatic zones and results obtained give a set of ideal EC glazing configurations in the case of EC window controlled by daylighting sensors.
A multiple Linear Regression Model to predict indoor temperature trend in historic buildings for book conservation: the case study of “Sala del Dottorato” in Palazzo Murena, Italy
Authors: Moretti Elisa , Proietti Maria Giulia , Stamponi Ettore
Published: December 2021

The indoor climate of historic buildings is governed by the desire to preserve them, their interiors and to ensure human comfort. For preservation of cultural heritage and libraries, relative humidity and temperature are very important parameters, including their amplitudes and changes rate in time. In the present study an experimental campaign of thermo-hygrometric parameters inside of “Sala del Dottorato”, located in Palazzo Murena (Perugia), is carried out. In this room a great number of rare and ancient books are preserved. The paper deals with the study and the evaluation of the correlation between outdoor and indoor microclimate conditions in the room, to ensure the proper conservation of the books; it is aimed at understanding how the two parameters follow outdoor variations and how the hygrothermal inertia of the building can mitigate these variations. This is done, specifically for temperature, which is the most critical aspect. Thanks to a continuous monitoring system for indoor and outdoor thermo-hygrometric parameters, a Multiple Linear Regression model is developed in order to predict and analyse the indoor temperature trend. This model allows to estimate a future forecast of this parameter and to predict in advance critical conditions for correct conservation.
Energy demand prediction with machine learning supported by auto-tuning: a case study
Authors: Ozaki Sorana , Ooka Ryozo , Ikeda Shintaro
Published: December 2021

The operational energy of buildings is making up one of the highest proportions of life-cycle carbon emissions. A more efficient operation of facilities would result in significant energy savings but necessitates computational models to predict a building’s future energy demands with high precision. To this end, various machine learning models have been proposed in recent years. These models’ prediction accuracies, however, strongly depend on their internal structure and hyperparameters. The time demand and expertise required for their finetuning call for a more efficient solution. In the context of a case study, this paper describes the relationship between a machine learning model’s prediction accuracy and its hyperparameters. Based on time-stamped recordings of outdoor temperatures and electricity demands of a hospital in Japan, recorded every 30 minutes for more than four years, using a deep neural network (DNN) ensemble model, electricity demands were predicted for sixty time steps to follow. Specifically, we used automatic hyperparameter tuning methods, such as grid search, random search, and Bayesian optimization. A single time step ahead, all tuning methods reduced the RSME to less than 50%, compared to non-optimized tuning. The results attest to machine learning models’ reliance on hyperparameters and the effectiveness of their automatic tuning.
Neural network for indoor airflow prediction with CFD database
Authors: Zhou Q , Ooka R
Published: December 2021

Energy efficiency and indoor thermal comfort are both important in built environment, making it necessary to simultaneously take into consideration of the two aspects, building energy performance and indoor environmental quality, at the design stage. Coupled simulation between building energy simulation (BES) and computational fluid dynamics (CFD) enables providing each other complementary information with regard to building energy performance and detailed indoor environment conditions; however, the main drawback of CFD in computational cost limits its application. Neural networks (NNs) are considered as promising alternatives for CFD due to their advanced modelling abilities and high-speed computational powers. This research aims to confirm the feasibility of NN for indoor airflow prediction, which extends previous studies from two-dimensional to three-dimensional indoor space for more realistic conditions. The NN receives boundary conditions as input and outputs corresponding velocity and temperature distributions. Comparisons were made between NN predictions and CFD simulations regarding accuracy and time consumption on testing cases. The results show that the NN reproduces indoor airflow and thermal distributions with relative errors less than 12%. Time consumption for predicting the testing cases is reduced by 80% with the NN. The feasibility of NN for fast and accurate indoor airflow prediction is confirmed.
Visual performance of home offices: a case study
Authors: Sarikaya C , Berger C , Pont U , Mahdavi A
Published: December 2021

The design of the lighting systems in conventional office environments is typically supported by domain specialists. However, the same is not true of home offices, whose arrangements frequently result from ad hoc and do-it-yourself activities. This circumstance may have ramifications for occupants’ health, comfort, and productivity, given the recent significant increase in home officing prevalence. In this context, the present contribution reports on a detailed case study of lighting conditions in a number of home office settings. Thereby, nine home offices (located in the city of Izmir, Turkey) were investigated. The home offices serve a variety of professionals. The study involved measurements under daylight and electrical light conditions. Moreover, simulations were conducted to explore improvement opportunities. The investigation results point to a highly uneven level of performance across the selected cases. The visual conditions were found to be generally better under daylighting conditions, despite some instances of excessive illuminance. Electrical lighting analysis results reveal in many cases insufficient light levels due, in part, to unsuitable types and positions of the luminaires. Simulation-based optimization exercises suggest that the visual conditions in the studied home offices can be considerably improved via changes in the number and types of the luminaires.
Determining Proper Daylighting Design Solution for Visual Comfort and Lighting Energy Efficiency: A Case Study for High-Rise Residential Building
Authors: Kiliç Z A , Köknel Yener A
Published: December 2021

Promoting the daylight performance that allows to provide visual comfort conditions by minimizing lighting energy consumption is possible with making a balance of window size, glazing type and shading strategy, which are the major design parameters of the daylighting system. Particularly, in high-rise buildings, where large openings enabling higher daylight availability and view out are preferred, the daylighting system becomes a crucial design consideration in terms of ensuring occupants’ visual comfort and improving lighting energy efficiency. This study aims to identify a proper daylighting design solution with regard to window area, glazing type and shading strategy for a high-rise residential building located in Istanbul considering visual comfort and lighting energy efficiency. The dynamic simulations are carried out by DIVA for Rhino version 4.1.0.12. The results are evaluated with the Daylight Autonomy (DA) to detect daylight availability in the space and Daylight Glare Probability (DGP) to describe the visual comfort conditions related to glare. Furthermore, the lighting energy consumption of each alternative is also analysed to determine the proper daylighting solution. The results have revealed that a proper daylighting solution providing visual comfort by improving lighting energy-efficiency can be determined by the evaluation of the daylight performance both qualitatively and quantitatively.
The influence of suspended ceilings on the impact sound insulation of wooden-beamed ceilings in a Wilhelminian style house
Authors: Maximilian Neusser , Paul Wegerer , Thomas Bednar
Published: December 2021

The refurbishment of Wilhelminian style houses, driven by the densification of the living space, is increasingly leading to problems in the field of sound insulation. The high-quality refurbishment of the outer shell of the existing buildings significantly reduces the basic noise level in living rooms. The focus of the project and the work shown is to improve the impact sound insulation of wooden beamed ceilings in Wilhelminian style houses without adding floor height. This ceiling systems show significant differences in its basic constructions compared to the modern wood-beamed ceilings (beam dimensions, spans width, etc.). The work shown examines different suspended ceilings constructions on a wood-beamed ceiling in a Wilhelminian style house. The conclusions are based on the measurement of the impact sound level in different construction phases according to ÖNORM EN ISO 16283-2:2018. An unknown influence are openings, in large numbers, in the suspended ceiling. These are often caused by the installation of lighting or by ventilation systems. The results show that depending on the resulting cross-sectional area of the holes, a reduction in the impact sound insulation is recognizable and should be considered in the planning process.
Indoor environmental quality and global comfort: an in-field study in workspaces
Authors: Puglisi G E , Spigliantini G , Oggiani N , Shtrepi L , Masoero M C , Corgnati S P , Astolfi A
Published: December 2021

The EN 16798-1 specifies the requirements to assess indoor environmental quality (IEQ) considering thermal, air quality, lighting and acoustics domains. A drawback of the standard is that it is based on an objective evaluation approach and does not account for the subjective perception. Also, the standard does not assess global IEQ nor comfort as a single index for the interaction of all the domains. This work tests the metrics proposed in the standard relating them to the occupants’ evaluations. An in-field monitoring campaign was performed in the ARPA headquarter in Aosta (Italy), acquiring quantities to be correlated with the subjective perception of IEQ gained through surveys. An insight on the possible approach to communicate IEQ and comfort feedbacks to the occupants was investigated to promote their awareness. Preliminary results show that the occupants’ perception can be predicted by adopting the approach proposed in EN 16798-1 in the case of thermal comfort, but limitations emerge about air quality, lighting and acoustics. Such result allows investigating how the environmental variables considered by the standard (e.g., the maximum sound pressure level or the maximum CO2 concentration) can be adopted as predictors of comfort, thus how new parameters and assessment methods should be introduced.
Indoor Air Quality and Overheating in UK Classrooms – an Archetype Stock Modelling Approach
Authors: Schwartz Y. , Korolija I. , Symonds P. , Godoy-Shimizu D. , Dong J. , Hong S.M. , Mavrogianni A. , Grassie D. , Mumovic D.
Published: December 2021

Children spend a large part of their waking lives in school buildings. There is substantial evidence that poor indoor air quality (IAQ) and thermal discomfort can have detrimental impacts on the performance, wellbeing and health of schoolchildren and staff. Maintaining good IAQ while avoiding overheating in classrooms is challenging due to the unique occupancy patterns and heat properties of schools. Building stock modelling has been extensively used in recent years to quantify and evaluate performance of large numbers of buildings at various scales. This paper builds on an archetype stock modelling approach which represents the diversity of the school stock in England through an analysis of The Property Data Survey Programme (PDSP) and the Display Energy Certificates (DEC) databases. The model was used for simulating Indoor-to-Outdoor pollution ratios to estimate indoor air pollution levels (NO2, PM2.5 and CO2) and thermal comfort (overheating) in two climate areas in England: London and the West Pennines. analysis highlighted variations in classrooms’ indoor CO2 levels in different seasons and explored the risk of overheating in relation to a classroom’s orientation.
Use of Beta Regression to investigate the link between home air infiltration rate and self-reported health
Authors: Lu S. , Symonds P. , Verschoor N , Chalabi Z. , Taylor J. , Davies M.
Published: December 2021

The UK has introduced ambitious legislation for reaching net zero greenhouse gas (GHG) emissions by 2050. Improving the energy efficiency of homes is a key priority in achieving this target and solutions include minimising unwanted heat losses and decarbonising heating and cooling. Making a dwelling more airtight and applying insulation can result in a lower energy demand by reducing unwanted heat loss through fabric and openings. However, the supply of sufficient outdoor air is required to dilute indoor airborne pollutants. This research investigates the relationship between dwelling air infiltration and self-reported health at population neighbourhood level for Greater London. This paper links data from a variety of sources including Energy Performance Certificates (EPCs), the Greater London Authorities’ Large Super Output Area (LSOA) Atlas and the Access to Healthy Assets and Hazards (AHAH) database at LSOA level. Beta regression has been performed to assess the influence of air infiltration rate on self-reported health, whilst controlling for other socioeconomic factors. All factors have been ranked in order of their association with self-reported health. Findings indicate that air infiltration rate has a positive association with the percentage of people reporting themselves to be in “good or very good” health.
Indoor air quality evaluation in naturally cross-ventilated buildings for education using age of air
Authors: Díaz-Calderón S F , Castillo J A , Huelsz G
Published: December 2021

Natural ventilation (NV) is a strategy of bioclimatic design to promote hygrothermal comfort and indoor air quality (IAQ). Nowadays, COVID-19 pandemic highlights the review of ventilation standards. In Mexico, the IAQ standard states a minimum of 6 ACH for educational buildings. ACH considers NV as an ideal piston flow and does not provide information of indoor airflow distribution. In this work, new age of air associated parameters are proposed, considering the indoor airflow distribution: the air renovation per hour (ARH) and the renovation parameter R. An isolated educational building located in a rural region is studied. Four window configurations of cross-ventilation are considered. All configurations have one windward window located at bottom. The configurations axial and upward have one leeward window at bottom and top, respectively. While, configurations corner and upward corner have one lateral side window at bottom and top, respectively. A CFD model of the educational building is validated with experiments. The axial configuration has the best performance according to ACH, nevertheless has the worst performance according to ARH and R. The results show that NV evaluation using ACH can lead to wrong decisions. An improvement of NV standard with the age of air associated parameters is recommended.