bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of heat pump combined two-stage desiccant wheel fresh air system of residential buildings in mixed climate zone
Authors: Tian Shaochen , Su Xing , Zhang Xu
Published: August 2019

The building requires dehumidification for a long period of time in mixed climate zone of China. As a conventional method for dehumidification, vapor compression systems remove the water vapor by cooling the process air below dew point. This system consumes a lot of energy for reheating the air to meet the requirement of supply air temperature. A heat pump combined with two-stage desiccant wheel (TSDW&HP) is proposed as an air conditioning and dehumidification system in this study. The operation performance of proposed system applied in a hypothetical residence with 3 residents was investigated and simulated by using TRNSYS software. The operation modes of the system are discussed for different scenarios of season and outdoor air humidity ratio. In dehumidification season, fresh air deals with all of the latent load. In air conditioning season, fresh air deals with all of the moisture load with part of the cooling load. When evaporation temperature of HP is reduced and more moisture load is processed by evaporator in air conditioning season, there is a balance point between the performance of DWs and heat pump. The energy consumption of TSDW&HP fresh air system was compared with a conventional fresh air conditioner during dehumidification season and air conditioning season. It was found that the energy-saving potential of this system is 27.3% compared with conventional air conditioner.
Thermal performance characterisation of a reverse-flow energy recovery ventilator for a residential building application
Authors: Hunt David , Mac Suibhne Naoise , Dimache Laurentiu , McHugh David , Lohan John
Published: August 2019

The European Union’s 2020 and 2030 sustainable energy policies seek significant reductions in both energy consumption and carbon emissions. These policies demand a greater use of energy efficient technologies and a transition away from fossil fuels. This paper studies one such technology, an indoor climate control system with a reverse-flow enthalpy recovery ventilator, capable of recovering both sensible and latent heat. The thermal performance characteristics are established using an experimental facility and calculation methods defined by European Standard EN 13141-7:2010. This involves measurement of temperature, humidity, pressure and volumetric air flow rates over a range of operating conditions. Total thermal energy recovery rates ranged from 0.63 kW to 2.2 kW, with energy recovery efficiency of 72.8 % to 88.6 %. The recovery efficiency ratio, which reflects the capacity of the indoor climate control system to recover thermal energy relative to its power consumption ranged between 6.87 to 19.97. Due to the unique reverse-flow defrost function, the system demonstrates operation down to -7 °C without frost formation. These results highlight the potential that this system can make towards the EU goals of reducing energy consumption, operating costs and carbon emissions associated with indoor climate control.
Caloric method for the energetic evaluation of decentralised domestic ventilation devices
Authors: Friebe Christian , Hantsch Andreas , Döge Sabine , Krause Ralph
Published: August 2019

In the context of this article, a caloric method for measuring the performance of alternating home ventilation devices (push-pull units) is presented. The simple and robust method provides both reliable and reproducible characteristic values. Based on this method, a test bench was developed and built. With this test bench the characteristic values (volume flow, heat recovery rate, temperature change rate) of series products can be measured. The aim of the investigation is the determination and evaluation of the possible parameters influencing the measurement. For this purpose, the parameters are illustrated on the basis of measured values from a defined test standard, consisting of a fan and electrical heating in a housing (so-called golden sample), as well as a pair of push-pull devices. As a result, suggestions for improvements to the previous procedure as well as approaches for further development are shown.
The evaluation of energy saving performance for the modular design centrifugal chiller
Authors: Hwang YoonJei , Park HanYoung , Oh SaiKee , Lee HoRim , Park YoungSu , Lee KamGyu
Published: August 2019

The modular concept design and operation of a centrifugal chiller offers the potential of increased cycle efficiency both at full load and off load conditions compared to the single compressor chiller. Modular chiller design is that a smaller, individual chiller can be connected with another, to make a larger capacity system. In the case of a tandem chiller, there would be faced to the higher initial cost or bigger foot print than a single compressor chiller at the same capacity because manufacturing cost, weight and size will be decreased according to increase of the refrigeration capacity. Therefore, it is obvious that a modular chiller have to be improved its efficiency first by both the operation algorithm and major cycle components. Eventually, the efficiency of the modular chiller achieves up to 6% at the full load condition after added series counter flow effect as much as 3% and more 3% added by improved aerodynamic design for impeller. Moreover, maximize off design potential through the capacity combination algorithm as the way of uneven loading makes 24% improved based on AHRI 550/590.
Numerical Investigation of School Stratified Ventilation Systems - A Ventilation Effectiveness Study
Authors: Adili Mohammad Reza , Engstfeld Simon , Stergiaropoulos Konstantinos
Published: August 2019

Good indoor air quality is an essential prerequisite for a healthy learning environment. Scientific research has shown that there is a direct correlation between air quality and pupils’ ability to learn. For the same supply air volume flow, stratified ventilation systems lead to an improved quality of breathing air than mixing ventilation systems. The ventilation systems that work on the stratified ventilation principle are therefore particularly suitable for the ventilation of classrooms. The air flow characteristics of these systems in classrooms are, however, not thoroughly investigated. In the context of this work, the air flow parameters of various school ventilation systems with stratified ventilation for a typical classroom will be investigated by means of Computational Fluid Dynamics (CFD). For this purpose, centralized ventilation systems with different air outlets as well as decentralized systems are examined and compared regarding their ventilation effectiveness and thermal comfort.
Development of HVAC Diffuser Unit for Task and Ambient Air Conditioning Allowing User to Control Built-in Fan — Evaluation of Air Supply Mode by Subjective Experiment and Field Measurement in Office
Authors: Akimoto Takashi , Odagiri Naoya , Nakashima Yoichi , Miyazaki Seiji , Yanai Takashi , Matsumoto Takashi , Yamashina Daiki , Araki Nana
Published: August 2019

HVAC diffusers have been developed that have dual functions for task and ambient air conditioning. In this study, we evaluated comfort according to air supply mode, strong or fluctuation mode, through a subjective experiment. We found that the fluctuation mode maintained greater comfort for longer compared with the strong mode under continuous airflow exposure. Therefore, the fluctuation mode is considered suitable for long-duration use. Moreover, field measurements in an actual office showed that the fluctuation mode was superior in terms of both comfort and energy saving compared with conventional air conditioning.
Model of Thermal Plume above Cooking Gas Stove for Designing Ventilation
Authors: Shimanuki Yuki , Kurabuchi Takashi , Toriumi Yoshihiro , Asawa Yasuhisa
Published: August 2019

A model of the thermal plume above a cooking gas stove using computational fluid dynamics (CFD) analysis was studied to predict the heat and vapor released during cooking. The combustion gas released from the burner installed in the gas stove was considered as air in which thermal energy was adjusted so that the thermal plume above the gas stove could be simulated. Therefore, the model could predict the thermal plume above the gas stove based on the capacity of the burner and pot size. For validating the simulated flow fields, the results of the velocity distributions above the gas stove calculated using CFD analysis models were compared with the results of the velocity distributions measured with particle image velocimetry (PIV). In conclusion, the analysis results were in good agreement with the measurement results. However, the velocity in the vertical direction calculated using CFD above the center of the burner was higher than the velocity measured using PIV along the axis from the center of the burner.
Influence of indoor conditions on microbial diversity and quantity in schools
Authors: Seong Dahae , Norman R. Sean , Hoque Shamia
Published: August 2019

HVAC systems consumes 37 % of the electricity in educational buildings. Energy consumption varies depending on the ventilation strategy. School buildings have a responsibility of ensuring energy performance and maintenance of indoor environmental quality for its occupants. This study assesses the efficiency of the ventilation system in terms of the microbes present in the spaces. Microorganisms and particulate matters were sampled in classrooms, locker rooms, libraries in two high schools and an elementary school. Six bacterial species and seven fungal species were identified. The most abundant microorganisms were Staphylococcus sp., Bacillus sp., and Micrococcus sp. Elementary school, especially kindergarten, showed higher microbial concentration and particulate matter as a result of higher human activity. Microbial concentration was influenced by the types of room in the same building with the same ventilation system. Canonical correspondence plot (CCA) determined that gender and school type have significant effects. The presence of Bacillus sp., Aerococcus sp., Corynebacterium sp., and Penicillium sp. was significantly related to gender, while Staphylococcus sp. and Alternaria sp. were related to type of school. The presence of Aerococcus sp. and Micrococcus sp. depended on the distance from the vent location. Relatively lower number of Aerococcus sp. was detected when the distance between sampling site and vent was less than 2 m. Micrococcus sp. was generally detected when the distance was < 3.5 m. The distance from the door was not significant.
Thermal performance evaluation of a high-density data centre for cooling system under fault conditions
Authors: Cho Jinkyun , Park Beungyong , Jeong Yongdae , Lee Sangmoon
Published: August 2019

In this study, an actual 20 MW data centre project was analysed to evaluate the thermal performance of an IT server room during a cooling system outage under six fault conditions. In addition, a method of organizing and systematically managing operational stability and energy efficiency verification was identified for data centre construction in accordance with the commissioning process. It is essential to understand the operational characteristics of data centres and design optimal cooling systems to ensure the reliability of high-density data centres. In particular, it is necessary to consider these physical results and to perform an integrated review of the time required for emergency cooling equipment to operate as well as the back-up system availability time.
Design of a Small-Scale Experimental Model of the International Space Station Crew Quarters for a PIV Flow Field Study
Authors: Georgescu Matei-Razvan , Nastase Ilinca , Meslem Amina , Sandu Mihnea , Bode Florin
Published: August 2019

An attempt at improving the ventilation solution for the crew quarters aboard the International Space Station requires a thorough understanding of the flow dynamics in a microgravity environment. An experimental study is required in order to validate the numerical models. As part of this process, a small-scale model was proposed for a detailed study of the velocity field. PIV measurements in water offer high quality results and were chosen for the subject. Following certain similitude criteria, an equivalence can be found between the results of these measurements and the real ventilation scenario. This paper describes the development process of this small-scale model as well as its performance in the initial test runs. Details regarding the advantages and weaknesses of this first model are the core of the paper, with the intention of aiding researchers in their design of similar models. The conclusion presents future steps and proposed improvements to the model.
Aircraft passenger comfort evaluation: sitting and standing passengers in commercial cabin
Authors: Moraes Clélia
Published: August 2019

This research investigates the evaluation of passenger comfort during a cruise airplane trip. The flow fields in the comfort design in commercial aircraft create contour conditions for the diffusers, cabinets and geometry cabin, responsible for providing a healthy environment to the passengers. The objective of this work is to characterize the airflow by measuring the velocity field and the air temperature inside the cabin. Based on the actual data, a computational fluid dynamics (CFD) analysis was performed using the Autodesk programming language for the simulations, in order to obtain information about the possible standards of easy and seated comfort for the passengers. The results of particle dispersion in the cockpit showed great influence of the ventilation system and the location in the aircraft where people generate the particles. Based on these results, the internal layout of the BWB2 airplane, also known as “Flying Wing” was projected. The projected cabin furniture features ventilation in order to attend the passenger’s need in flight. It is noted that the incipient individualization of the passenger’s thermal comfort configures one of the biggest problems faced by the airlines. Consequently, It is a possible differential for competition between airlines.
Energy flexibility of office buildings – Potential of different building types
Authors: Liu Mingzhe , Johra Hicham , Heiselberg Per Kvols , Kolev Ivan , Pavlova Kremena
Published: August 2019

The objective of this study is to investigate and assess the energy flexibility performance of typical Danish office buildings constructed at different periods. Four building study cases have been compared with different heating demands, structural thermal masses, envelope insulation levels and infiltration rates. All cases are equipped with the same novel two-pipe heating and cooling system. Each case is divided in four subcases with variations of heat gains: people load, lighting load, equipment load, solar gain. Analyses and comparisons have been performed on different parameters, including power load shifting and grid adjustment, comfort level, and economical benefits. All investigated cases are tested with two control strategies: a normal reference control strategy and an energy flexibility control. The flexible controller adjusts the indoor temperature set points for heating and cooling depending on different energy price levels.
Numerical approach regarding functional and design optimization for a residential building daily hot water system composed by heat pump and auxiliary source
Authors: Talpiga Mugurel Florin , Mandric Eugen , Iordache Florin
Published: August 2019

In this paper is presented the physical model and mathematical approach which describe the equation system used in system calibration and design optimization. The system proposed for study is built from heat pump, for energy demand delivery, together with auxiliary heating source to face in all low temperature days, when heat pump work at maximum load but the required demand for daily hot water by the building inhabitants is higher. The paper present few of the common used systems in market for which the mathematical equation system will be proposed to come in help designers for in simulation and cost optimization. Simulation of proposed design is realized and results are delivered. The system construction, is optimized by comparison study of design and simulation data for each system type proposed. The comparison study is used for cost estimation of system and energy balance.
Numerical approach regarding functional and design optimization for a residential building heating system composed by heat pump and auxiliary
Authors: Talpiga Mugurel Florin , Mandric Eugen , Iordache Florin
Published: August 2019

In this paper is presented the physical model and mathematical approach which describe the equation system used in system calibration and design optimization. The system proposed for study is built from heat pump, for energy demand delivery, together with auxiliary heating source to face in all low temperature days, when heat pump work at maximum load but the required demand by the building is higher. The paper present few of the common used systems in market for which the mathematical equation system will be proposed to come in help designers for in simulation and cost optimization. Simulation of proposed design is realized and results are delivered. The system construction, is optimized by comparison study of design and simulation data for each system type proposed. The comparison study is used for cost estimation of system and energy balance.
Optimising the Number of Pumps and Balancing Valves in Chilled Water Distribution Systems
Authors: Retezan Adrian , Geyer Ehrenberg Szilveszter
Published: August 2019

Everyday life does involve use of cooling systems for different areas and scenarios. We use them to keep our thermal comfort level at optimum, either to get rid of some extra heat from technological systems. From various cooling solutions, one and very common system is the chilled water system, where centralised chiller plants produce the cooling energy and all terminal units do receive cooling energy using a distribution loop. According to statistical data, electrical energy consumption of pumps might be up to 17% of entire electrical use of the cooling plant. When designing our cooling system loads during operation will not be same all the time. Variation must be treated accordingly, therefore to get best efficiency of the system, we must get a good control. Beside shut-off motorised valves our balancing must be considered in different scenarios. The paper looks to summarize the challenges in getting a good balancing and energy efficiency in chilled water distribution system.
Full-scale operation of a novel two-pipe active beam system for simultaneous heating and cooling of office buildings
Authors: Maccarini Alessandro , Hultmark Göran , Bergsøe Niels C. , Afshari Alireza
Published: August 2019

This paper presents an investigation on the operation of a novel active beam system installed in an office building located in Jönköping, Sweden. The system consists of two parts: a dedicated outdoor air system (DOAS) to satisfy latent loads and ventilation requirements, and a water circuit to meet sensible heating and cooling loads. The novelty of the system is in relation to the water circuit, which is able to provide simultaneous heating and cooling through a single water loop that is near the room temperature. The energy performance of the system is currently being monitored through a number of sensors placed along the water circuit. Relevant physical parameters are being measured and data are available through a monitoring system. A preliminary analysis shows that the system is performing as designed. Results are shown for a typical week in winter, spring and summer. In particular, the supply water temperature in the circuit was between 20°C (in summer) and 23.2°C (in winter). The maximum supply/return temperature difference was found in summer and it assumed a value of 1.5 K. It is noticed that in spring supply and return water temperatures almost overlap.
Estimation of load duration curves from general building data in the building stock using dynamic BES-models
Authors: Mahmoud Rana M. , Sharifi Mohsen , Himpe Eline , Delghust Marc , Laverge Jelle
Published: August 2019

Modelling and simulation of building stock is a valuable source of information for investigating the feasibility of implementing new heating and cooling system technologies. Some of these technologies have oversizing problem as the designers rely on their experience and previous knowledge. Building stock modelling can provide a solution for more accurate designing process. However, some of the current building stock modelling methods uses a representative building which can exclude whole ranges of the different combinations of building geometry and physical properties that can be crucial for heating and cooling load estimation. Therefore, we developed a methodology that allows faster and accurate building energy simulation (BES) multizone models from general building information of the whole building stock that is able to estimate load duration. This will help engineers and designers to decide on the system sizing at the early design stages. This paper presents first, the process of generating dynamically heating and cooling load duration curves by using BES-models from general geometrical data of the building stock. Second, we examine the process on a sample of the building stock where geometrical and physical parameters were varied. The workflow of the process has worked successfully, generating heating and cooling duration curves for 14 case studies. We observed that heating and cooling loads are highly influenced by different combinations of parameters. High glazing percentage affects highly the heat losses, thus more heating loads. Besides, for a west oriented building, the high glazing percentage combined with high internal gains can be the reason for significant cooling loads. In next steps, we are going to extend the current methodology to cover different building typologies within different climates across Europe.
The Examination of Air Blowing Method and Thermal Comfort of Variable Air Conditioning System using Coanda Effect
Authors: Sakakibara Hikari , Akimoto Takashi , Igarashi Hitomi , Nakamura Shunsuke , Kimura Madoka
Published: August 2019

The “Strategic Energy Plan” implemented by the Cabinet of Japan in 2014 strives for zero energy building design for typical new construction by 2030. The present study focuses on a ductless and variable air conditioning system, using the Coanda effect, with the aim of reducing fan power, and saving of resources by reducing the space between the ceiling. In this study, we examined the air blowing method and evaluated thermal comfort using computational fluid dynamics as well as subjective perception of coolness in a midsize office. A draft zone was reduced by extending the interval between conditioned air outlets. However, if the extension of throw length was excessive, hot space would be formed near the air outlets, and there would be a risk of impacting thermal comfort. Moreover, we confirmed that the thermal comfort was generally favourable. In particular, perceived thermal comfort was better at the position in the office where the air flow landed on the upper body of the subjects. On the other hand, it decreased when the influence of the air flow was small, and at the point where air flow landed on the lower body of the subjects.
Cooling performance of Ceiling Radiant Textile Air Conditioning System with Ceiling Cassette Unit of Packaged Air Conditioner
Authors: Yamanaka Toshio , Kuranaga Mari , Maeda Tatsunori , Kitakaze Haruto
Published: August 2019

The authors developed a new radiant air conditioning system named ceiling radiant textile air conditioning system with ceiling cassette unit of packaged air conditioner (PAC). The nonflammable textile is stretched under the ceiling with ceiling cassette units of PAC with a distance of around 30 cm. The aim of this study is to investigate the cooling performance of this new radiant system, so the experiments with full scale model were conducted for three system. The first system is “textile only”, the second system is “textile with guide for air return grille” and the third system is “textile with guide and opening for air return grille”. Airflow rate through textile is measured by tracer gas method. In all cases, the vertical temperature distribution is almost uniform, and the cooling effect of “textile with guide and opening for air return grille” is the largest. As for the radiant effect, two systems of “only textile” and “textile with guide for air return grille” are superior to “textile with guide and opening for air return grille”. The airflow rate trough textile is doubled when using guide, and increased by five times if the opening was provided under the guide.
Interaction of GEOTABS and secondary heating and cooling systems in hybridGEOTABS buildings: towards a sizing methodology
Authors: Sharifi Mohsen , Mahmoud Rana , Himpe Eline , Laverge Jelle
Published: August 2019

GEOTABS, a combination of TABS with a geothermal heat pump, is a promising heating and cooling system for decreasing greenhouse gas emissions in the building sector. However, TABS has a time delay when transferring energy from the pipes to the room. So, when the heat demand changes fast, TABS cannot properly compensate the heat demand. In order to solve this problem and maintain thermal comfort in the room, the concept of hybridGEOTABS proposes using a fast secondary system to assist the TABS. Yet, there is no integrated method for sizing both systems in a hybridGEOTABS building, considering the interaction between the secondary system and GEOTABS. This study will provide an integrated sizing methodology for hybridGEOTABS buildings. To that purpose, in this paper the interaction between the secondary system and TABS is investigated for two different scenarios by using a preference factor between the TABS and the secondary system. The methodology starts from heat demand curves, an analytic model for TABS, and optimal control principles for TABS to minimize the total energy use while providing thermal comfort. Finally, the method is used for 4 case studies in different scenarios with different secondary systems. Preliminary results of this research indicate that the secondary system type doesn’t have effect on the strategy of sizing. Therefore, designer can decide about secondary system type with investment and operating cost analysis.
Standardization of building technology on demand via robotic
Authors: Henne Andreas , Kloster Nina
Published: August 2019

Although the basic installation arrangement and sequence within Technical Building Equipment, based on generation, distribution and transfer of energy quantities, has remained virtually unchanged for some time, this essentially grid-connected world of installations could soon change significantly for different reasons. This feasibility study presents an almost disruptive approach, based on mobile multifunctional, chargeable and unchargeable PCM-TGA robot technology, which should be able to perform room conditioning (esp. heating, room air quality) as well as room monitoring in at least two rooms via a mobile module. Charging takes place at a plug and play transfer station, e.g. via a decentralized heat pump system integrated in the brickwork. First, the authors show the transdisciplinary reasons, which are essentially socio-politically evidence-based, for the need for additive technological development. Then, both the overall system that consists of a decentralized plug-and-play heat pump transfer station integrated in the brickwork and a mobile robotized heat distribution system, which is not tied to a pipe system, are explained. Based on an exemplary floor plan, living areas will then be shown that require permanent conditioning as well as those that can have discontinuous conditioning via the robot. Feasibility is demonstrated by means of building simulation of the load profiles, leading to appropriate storage dimensioning using a suitable phase change material. Here the authors refer to their extensive theoretical and experimental knowledge in handling dynamic PCMs when creating a prototype. Finally, the technological approach undergoes a critical assessment.
Impact of Negative Pressure in a Room Due to Increased Airtightness in Residential Apartment Housing
Authors: Toriumi Yoshihiro , Kurabuchi Takashi
Published: August 2019

This study surveyed the impact of a negative pressure in a room in a highly airtight residential apartment with Class 3 ventilation (natural air intake and mechanical exhaust). The results of the study are as follows. 1) A room may reach an excessive level of negative pressure depending on how the ventilation system is used. 2) Noise from the drain pipe of a room air conditioner caused by negative pressure in the room is dependent on how the drain pipe is installed. 3) An experiment was conducted to investigate the mechanism of a seal break in a toilet trap. However, the seal did not break. Thus, seal breaks may be caused by multiple factors.
Investigations on a hybrid element with cellular metallic material for heating, cooling and ventilation
Authors: Schinke Lars , Schlott André , Beyer Maximilian , Seifert Joachim , Fink Marcel
Published: August 2019

Surface heating and cooling systems are gaining more and more importance in building energy technology. In order to implement these systems not only on the floor but also on the ceilings and walls, the thermodynamic requirements are supplemented by constructional requirements. In order to fulfil these requirements, the use of open-cell porous metals for such systems will be investigated in more detail. In addition to the design and manufacturing challenges, a large number of numerical and experimental investigations on test samples are also necessary. These investigations are described and explained in more detail in the following article.
Incorporating cooling and ventilation effects into a single IEQ indicator
Authors: Prek Matjaž , Krese Gorazd , Lampret Žiga
Published: August 2019

The influence of dissimilar cooling and ventilation system combinations on indoor environmental quality (IEQ) has been studied. A comparison of chilled ceiling cooling in combination with displacement ventilation, cooling with fan coil unit, and cooling with flat wall displacement inlets was performed. All observed variations were evaluated based on whole-body and local thermal comfort criteria as well as with regard to ventilation effectiveness. The analysis was made based on results of numerical simulations carried out in two steps. First, DesignBuilder was applied to model the buildings’ thermal performance and to evaluate its interaction with the environment. The latter included the calculation of heat gains as well as the heat loss on the boundary surfaces of the observed air-conditioned room. In the second step, ANSYS Fluent was used to simulate the response of indoor environment by utilizing the simulation results obtained in the first step, in order to evaluate the interaction between building and human. Afterwards, the observed thermal comfort and ventilation criteria were merged into a novel indoor environment indicator, which enables to describe the indoor environment quality with a single value. Among the analysed systems, the ceiling cooling system in combination with displacement ventilation was found to be the most suitable as it offers a high level of thermal comfort with adequate ventilation efficiency. Fan coil cooling was the least favourable option in terms of thermal comfort, while flat wall displacement inlets exhibited the lowest ventilation effectiveness. The performed investigation demonstrated the necessity to assess indoor environment with regard to IEQ in addition to energy consumption.
Influence of installation of displacement ventilation diffusers above occupied zone on the vertical temperature gradient in simulated office rooms
Authors: Mustakallio Panu , Kosonen Risto , Ruponen Mika , Lastovets Natalia
Published: August 2019

Displacement ventilation diffusers are typically installed to the occupied zone, which can limit the utilization of the displacement ventilation. This paper presents the full-scale test results of two simulated office rooms with installation of displacement diffusers near wall, above the occupied zone. Vertical temperature gradients are compared to full-scale tests with installation of displacement diffusers to the occupied zone. The full-scale test setup consisted of two displacement diffusers and ceiling exhaust in wellinsulated room with 20.7 m2 floor area and room heights of 5.1 m and 3.3 m. The internal heat loads simulated situations with 10 occupants (simulated with heated cylinders), fluorescent lighting units, solar load on window surface (heated foils in one wall) without/with direct solar load on floor (heated foil on floor). The installation of displacement ventilation diffusers above occupied zone influenced on the vertical temperature gradient above the occupied zone only slightly. It reduced the vertical temperature gradient in the occupied zone. This confirms the operation of the displacement ventilation with this installation. This can be advantageous due to the smaller temperature stratification in the occupied zone, still the ventilation efficiency can be slightly lower comparing to the typical installation of the displacement diffusers.
Finnish Guidelines of Ventilation Rates for Non-residential Buildings
Authors: Seppänen Olli , Säteri Jorma , Ahola Mervi
Published: August 2019

The new Finnish Decree on the Indoor Climate and Ventilation of New Buildings 1009/2017 [1] is part of the implementation of Energy Performance of Buildings Directive in the EU. The new Decree specifies the minimum design ventilation rate to be 6 dm3/s, person (outdoor air). The Decree also specifies that the ventilation shall be controlled by demand when feasible. These requirements in the Decree were considered to be too plain and inadequate for practical design. FINVAC carried out an investigation [2,3] regarding the experience on the old ventilation regulation [4]. Based on the result of these investigations new guidelines were prepared and published in 2018. Majority of the experts considered 6 dm3/s, person as an appropriate value of the minimum ventilation rate. The investigations revealed that in many cases the old recommended values (dm3/s, m2) were either too high or too low. This has led to poor air quality in some cases and excess energy use in some cases. Too high ventilation rates were used for corridors, restaurants, cafeterias, supermarkets, department stores, shops, hotel rooms, auditoriums, halls, and washing rooms. The total air flow was also too high for day care centres, and for some apartments. Too low ventilation rates were given for elderly homes, classrooms, fitness centres, sports halls, residential kitchen hoods, operation rooms in hospitals, and for some apartments. Detailed guidelines were prepared and structured by building type (offices, schools, hospitals, elderly homes, restaurants, hotels, stores, sports facilities, barracks, theatres, industrial working places, kitchens, spaces for personal hygiene and technical rooms). Separate guidelines were prepared for residential buildings [5]. Both guidelines were published in the beginning of the year 2018.
Studying the influence of moving vehicle on air pollutant dispersion through environmental chamber
Authors: Chow T.T. , Zhang Wenjing , Wang Jinliang
Published: August 2019

The risk of air pollutants like particulate matters on human beings has been widely reported. One main concern is its health impact on people through direct emission or resuspension. In China with the quick growth in private car ownership, the worries about the influence of the moving vehicles on particulate dispersion is growing. In this study, the influence of a moving object on wick formation and particulate dispersion was investigated. An advanced numerical model was developed, in which the unsteady Eulerian RANS model was applied for simulating the airflow, the modified drift-flux model for modelling particulate dispersion, and the dynamic mesh model for mimicking the moving vehicle. The results show that the vehicular movement induces three noticeable vortexes around the moving body, and the faster the running speed, the stronger the secondary airflow generated.
Evaluation of Short-Distance Airborne Infection Risk Using a Cough Generator
Authors: Ling Wei , Ichikawa Maho , Hashimoto Kaho , Ogata Masayuki , Tsutsumi Hitomi , Morimoto Shoichi , Tanabe Shin-ichi , Hori Satoshi
Published: August 2019

Short-distance airborne infections are often thought to occur by large droplets or direct contact. Recent studies have investigated the phenomenon of short-range airborne infection. In this study, the effect of relative humidity and short-distance exposure to cough droplet nuclei were evaluated. The evaluation model for infection risk was designed based on experimental data and previous studies and included sampling efficiency and virus survival rate. As observed in the comparison between short-range exposure and long-range exposure, the short-range exposure to the droplet nuclei by one cough was equivalent to a long-range exposure of several seconds to, depending on the number of ventilations, even for a momentary high-concentration exposure. This suggests the possibility of an infection risk corresponding to the receiving condition. Since short-range exposure and long-range exposure have different factors affecting the risk of infection, it is suggested that effective infection control should be selected for each condition. The risk of infection due to long-range exposure is considered to be sufficiently reduced to that of a single cough if the building meets the necessary number of ventilations. It was suggested that the influence of relative humidity on infection risks is smaller than other factors such as ventilation.
The effect of wall and floor colouring on temperature and draught feeling of primary school children
Authors: Bluyssen Philomena M. , Zhang Dadi , Krooneman Arend-Jan , Freeke Arno
Published: August 2019

To investigate whether different colours of the indoor surfaces could have an effect on thermal comfort of children, 335 primary school children were invited to take part in a series of tests conducted in the thermal test chamber of the SenseLab. A three-way factorial randomized design was used to test the effect of three different colours of walls (white, red and blue) and floor (grey, green and blue) on the temperature and draught feeling in a winter situation (sunlight coming in: heat) and a summer situation (opening window: draught). A statistical relevant relationship between feeling of draught and feeling of temperature was found. Except for a significant difference in temperature feeling for different floor colours when the wall colour was red in the winter situation, no relevant effects (or interaction effects) were found for differences in wall or floor colours on the temperature or draught feeling.
Numerical Investigation of Air Conditioners’ Control Unit Position On Temperature Distribution and Energy Consumptions of a Room
Authors: Mutlu Mustafa , Çalışkan Emre
Published: August 2019

Minimum temperature difference should be achieved in conditioned rooms to meet comfort criteria. It is desired that the temperature set by a user from the control unit, should be the same in the entire room. Therefore, the position of the control unit plays a significant role in order to achieve a homogeneous temperature distribution in the room. In this study, the effect of control unit positioning on temperature and velocity distributions in a room, where a cassette type indoor unit was applied, was numerically investigated. Blowing temperature and speed of the indoor unit has been adjusted by the temperature value that measured by a control unit which was placed at five different locations, in order to examine positioning effects of the control unit. Predicted percentage dissatisfied (PPD) values were calculated, and uncomfortable zones were determined by 2-dimensional analyses. Cooling loads, as well as energy consumptions, were calculated and their variations according to the position of control unit was figured out in steady state conditions. The results showed that control unit positioning not only influences the comfort levels or temperature distributions in a room but also energy consumptions.
Effects of ambient temperature, airspeed, and wind direction on heat transfer coefficient for the human body by means of manikin experiments and CFD analysis
Authors: Gao Shan , Ooka Ryozo , Oh Wonseok
Published: August 2019

The purpose of this study is to confirm the effect of ambient temperature, airspeed, and wind direction on the heat transfer around the human body. A fixed surface temperature (33 °C) thermal manikin (TM) with 16 segments was employed. First, the manikin was placed in a climate chamber with ambient temperatures of 20 °C, 24 °C, and 28 °C, at airspeeds of less than 0.1 m/s to represent calm condition. Higher ambient temperatures led to a decrease in the convective heat transfer coefficient. The convective heat transfer coefficients for the sitting posture were higher than those of the standing posture. The same TM was then put in a wind tunnel with airspeeds ranging from 0.25 m/s to 1.4 m/s to represent forced convection. The TM was set to face upwind, downwind, and perpendicular to the wind (i.e., its right side facing the wind). Regression models for the convective heat transfer coefficient and airspeed for different wind directions and postures were derived. In contrast to the calm condition, the convective heat transfer coefficients for the sitting posture were lower than those for the standing posture. The convective heat transfer coefficients for the standing posture were largest when the TM was facing downwind, and smallest when the right side of the TM was facing the wind. To verify the results of the experiment, computational fluid dynamics (CFD) analysis was performed with conditions matching those of the experiment by using a computational TM with the same shape as that used in the experiment. The boundary conditions of the CFD analysis were set from the experiment. The CFD analysis results were consistent with the experimental data.
Verification of the effect of sleeping environment and humidification on middle-aged people in whole-house air-conditioning ventilation system housing
Authors: Iwaki Akemi , Akimoto Takashi , Misumi Naho , Furuhashi Takuya
Published: August 2019

This study focused on the thermal comfort of air circulation-type whole-house air-conditioning ventilation systems. We studied the influence of 24-h continuous whole-house air-conditioning on the living environment in which the occupant is sleeping. A survey was conducted in the summer of 2016 and winter of 2017 to ascertain the influence on the sleeping environment, skin moisture content, and blood pressure. We then compared the results with those of the sleeping environment of residents in air-conditioned housing surveyed the previous year. The sleeping environment when using a personal humidifier around the occupant’s head was examined during winter when the humidity is low. The results indicated that sleep latency was significantly shortened in the 24-h continuous whole-house air-conditioning ventilation system in both summer and winter because the temperature control of the bedroom before going to bed affects the sleep latency. Subjectively, no participants felt dryer than the values measured in the bedroom environment. The results implied that the comfort of the entire building was improved with continuous air-conditioned housing.
The Influence of textile floor coverings on the indoor air quality
Authors: Vasconcelos Silvia de Lima , Sattler Marcel , Müller Birgit , Plehn Wolfgang , Horn Wolfgang
Published: August 2019

Textile floor coverings are often used in offices and residential buildings. Large areas like meeting rooms, cinemas, theaters and hotels are often equipped with such coverings. They contribute to the comfort of the users as they provide high pedaling comfort and sound absorption. The weakness of these building materials is due to the odor emission that is released from the floor covering, which affects the comfort of the users. A bad air quality and the resulting dissatisfaction can lead to lower employee productivity [1] [2]. The research project of the Hochschule für Technik und Wirtschaft Berlin (HTWBerlin) is promoted by the German Environment Agency (UBA). The project has the following title: Lowemission and low-odor building products for energy-efficient buildings - Development of requirements and concepts for the Blue Angel from a climate protection perspective; investigates the emission and odor behavior of textile floor coverings (Emissions- und geruchsarme Bauprodukte für energieeffiziente Gebäude - Entwicklung von Anforderungen und Konzepten für den Blauen Engel aus Klimaschutzsicht; untersucht das Emissions- und Geruchsverhalten textiler Bodenbeläge). The results of the study are shown in this paper.
On the improvement of thermal comfort in indoor spaces conditioned by split-type systems
Authors: Anastácio da Silva Júnior , Kátia Cordeiro Mendonça , Rogério Vilain , Luiz Pereira Marcelo , Nathan Mendes
Published: August 2019

Conventional on/off-based control split-type appliances are widely used in classrooms and offices, in Brazil and in many other countries, due to their low cost and ease of installation. However, occupants often complain about thermal discomfort depending on their position within the conditioned space, especially in positions that are directly affected by the draft, since those equipment provide high cold air velocities as a result of their high cooling capacity relatively to their air supply area. In order to improve the indoor thermal comfort in spaces conditioned by this kind of system, a simplified empirical model for controlling both the supply airflow and the temperature set-point is proposed in this work. In view of that, the comfort conditions in an occupied classroom were experimentally evaluated according to ISO 7730 Standard, which defines the thermal satisfaction in occupied environments based on the PMV index. Specifically, the speed, temperature and relative humidity of the air and the mean radiant temperature of the room were measured at 8 positions within the air conditioned space, for the three original air flows (high, medium and low) of a 10.5-kW cooling capacity appliance and three set-point temperatures (23, 24 and 25 °C). The simplified model, correlating thermal comfort and the variables that could be directly controlled by the split-type system (airflow rate and temperature), was obtained by adjusting several curves from 72 measuring assemblies (8 measuring points, 3 set-point temperatures and 3 supply airflows). The correlation that best represents the distribution of thermal comfort throughout the conditioned environment was provided by the non-linear regression method of Levenberg-Marquardt.