Room Air Exchange Research Articles

Ventilation and air conditioning design approach based on ASHRAE psychrometric chart and Mollier diagram

Society needs long-term sustainability and healthy building projects, and indoor air quality assurance engineering systems play a pivotal role in the energy performance of buildings. Therefore, when designing heating, ventilation, and air conditioning systems, it is crucial to make the most technically sound decisions in terms of energy consumption and assess their impact on the building’s energy performance. This article delves into the design of ventilation and air conditioning systems, presenting a method for evaluating their performance. The foundation of project development is an agreement on the design criteria, which are developed based on a preliminary analysis of the building concept. This agreement ensures cohesive collaboration among all stakeholders: the client, the architect, the system designer, the contractor, and ultimately the personnel responsible for commissioning, operating, and maintaining the systems post-construction. We suggest conducting a comprehensive analysis of the processes occurring within the space without initially linking them to room air exchange. From this analysis, we derive the angular coefficient for the direction of the air condition change on both a psychrometric chart and a Mollier diagram. The process line on the psychrometric chart provides insights into how the performance factor of the air distribution system will influence the desired supply air parameters. We can then evaluate how significantly the gap between the supply air and the exhaust air parameters expands if the room’s air exchange volume is reduced for budgetary reasons. The article showcases this design methodology using a simplified case study.

Effects of operating room ventilation on particle exposure and removal during general endotracheal anesthesia

The operating room (OR) ventilation system is a primary method for reducing particle exposure in the OR. However, most ventilation studies in operating rooms were conducted using computational fluid dynamics (CFD) models, which may not be able to predict the complexity of real operating conditions. In this study, we recruited 40 patients undergoing general endotracheal anesthesia in a total of 13 operating rooms. We tested the effectiveness of OR ventilation on mitigating patient and nebulizer-generated particles during the preoxygenation, induction, and intubation phases of care. Sampling locations were selected close to the patient's face (reference), physician's head area, and medical assistant's standing location. A total of six sampling sessions characterizing patient and healthcare worker activities were included. We observed a significantly higher number of particles during endotracheal intubation compared to preoxygenation with deep breathing and coughing, suggesting potential disruptive effect of surgical activities (i.e., intubation) on airflow, which affected particle concentration. Particle decay rates measured at all three locations (reference 50 ± 20 h-1; physician 46 ± 22 h-1; medical assistant 33 ± 21 h-1) were considerably higher than the regulated operating room air exchange rate of 20 h-1, indicating highly effective overall ventilation function. Nevertheless, healthcare workers should still be cautious about particle exposure risks in operations that generate large number of particles. Results from this study reflect the effectiveness of OR ventilation on particle mitigation in real-world scenario and may facilitate the validation of future CFD studies as well as the establishment of effective OR regulation guidelines to protect healthcare workers from particle exposures.

Airborne influenza virus shedding by patients in health care units: Removal mechanisms affecting virus transmission.

In this study, we characterize the distribution of airborne viruses (influenza A/B) in hospital rooms of patients with confirmed infections. Concurrently, we monitored fine particulate matter (PM2.5 & PM10) and several physical parameters including the room air exchange rate, temperature, and relative humidity to identify corresponding correlations with virus transport and removal determinants. The results continue to raise concerns about indoor air quality (IAQ) in healthcare facilities and the potential exposure of patients, staff and visitors to aerosolized viruses as well as elevated indoor PM levels caused by outdoor sources and/or re-suspension of settled particles by indoor activities. The influenza A virus was detected in 42% of 33 monitored rooms, with viruses detectible up to 1.5 m away from the infected patient. Active coughing was a statistically significant variable that contributed to a higher positive rate of virus detection in the collected air samples. Viral load across patient rooms ranged between 222 and 5,760 copies/m3, with a mean of 820 copies/m3. Measured PM2.5 and PM10 levels exceeded IAQ daily exposure guidelines in most monitored rooms. Statistical and numerical analyses showed that dispersion was the dominant viral removal pathway followed by settling. Changes in the relative humidity and the room's temperature were had a significant impact on the viral load removal. In closure, we highlight the need for an integrated approach to control determinants of IAQ in patients' rooms.

Ammonia Dispersion in the Closed Space of an Ammonia Engine Room with Forced Ventilation in an Industrial Plant

Air pollution is a global problem that is responsible for more than four million premature deaths each year. Air exchange in ammonia engine rooms is a priority for normal operating conditions, as well as in the event of an emergency release. A numerical approach with the use of computational fluid dynamics techniques can provide detailed data, such as spatial gas dispersion. Therefore, the objective of this study was to prepare a mathematical tool for the assessment of ammonia distribution in an engine room equipped with forced ventilation as a prediction tool for dangerous industrial setup working configurations. This study analyzed the uncontrolled release of ammonia during the production process in an engine room using Ansys Fluent software. It was observed that emergency ammonia leakage of 0.1 kg/s in the assumed air flow poses a great threat to the mechanics. In many simulated scenarios, ammonia spread to the entire building. Moreover, the mass fraction of ammonia was the highest in the gas stream right after its release. After being released, ammonia often accumulated in the ceiling zone, and in inactive exhaust chimneys, air inlets, and doors. It was observed that the effectiveness of the ventilation analyzed depended on the number of active air vents and exhausts, as well as their spatial distribution throughout the building.

Assessment age of air and thermal comfort in a classroom by adopting displacement ventilation with chilled ceiling system

This study aims to investigate the effect of the cooling load ratio covered by the chilled ceiling on the age of air and comfort level in a classroom in a hot and dry climate in Iraq-Hilla city. Air age, air exchange efficiency, and concentrations of pollutants in a classroom are investigated numerically by used AIRPAK software under displacement ventilation combined with a chilled ceiling system. Four cases are studied at different values of the cooling load covered by the chilled ceiling (0%, 25%, 50%, 80%) with respect to total classroom cooling load. Cooling load removes by chilled ceiling varied from (0 to 84.5 W/m2) based on the classroom area, and its temperature varied between (17.5-22.5oC). The displacement ventilation airflow rate was kept at 0.3m3/s, and the air temperature supply varied between (19.5-24.5oC) depend on the amount of cooling load covered by displacement ventilation. The results showed that the mean local air age increasing with height. The room mean air age increase and air exchange efficiency reduce with increasing load portion, which treated by the chilled ceiling. Increasing the portion of the load treated by chilled ceiling tends to improve comfort levels.

Role and responsibility of operating room nurse in preparation operation theatre for HIPEC and cytoreductive surgery in the tertiary health center in north India

Hyperthermic (or Heated) Intraperitoneal Chemotherapy (HIPEC) is a surgical procedure that’s giving new hope to patients with abdominal cancers. Immediately after removing visible tumors through cytoreductive surgery, surgeons give a dose of heated chemotherapy inside a patient’s abdomen. The technique involves macroscopic resection of disease burden and metastases, followed by infusion of chemotherapy heated to 41°C–43°C into the peritoneal cavity through a special device. After 90 minutes of the infusion, the chemo is washed out and incisions are closed. Chemotherapy: -In HIPAC (Intraperitoneal) mitomycin-c is the most common drug administrated and platinum-based drugs, cisplatin, carboplatin, and oxaliplatin which have a synergistic effect with heat, and doxorubicin, paclitaxel, docetaxel, and 5-fluorouracil drugs are commonly less used. The technique of Hyperthermic intraperitoneal chemotherapy Administration: HIPEC is administrated by two classical methods, the open abdomen method, and the closed method. Skin preparation of patient: Skin preparation is from the mid-chest to midthigh with the preparation of the genitalia and catheterization.Safety guidelines for administration of HIPEC: A sign the HIPEC is in progress should be placed at the door and the entry of personnel not involved in the procedure should be restricted. N95 grade mask provides the best protection against surgical smoke produced during the use of electrocautery. Doors should be closed during the operation with pressurized closures. The temperature should be 18–26 degrees Celsius and air humidity 45–60 %. The Association for peri-Operative Registered Nurses (AORN) recommends that operating room air exchanges should be maintained at a minimum of 15 air exchanges per hour. Air inflow volume should be 15 % higher than the outflow, airspeed must be lesser than 0.3 m/s. Appropriate PPE (personal protective equipment) consists of an N95 face mask (a simple surgical mask does not provide adequate protection), gloves, protective gown, and overshoes or laggings to provide adequate protection to all involved team members.Handling of the chemotherapy during HIPEC: it should be prepared in the bio-safety cabinet not in the ward because of the danger from spillage and contamination, while preparing cytotoxic drugs to wear nitrile or neoprene powder-free long cuff gloves and wear a gown non-permeable long sleeve, cuffed and solid fronted and use an aerosol-free mask. Every effort should be taken to avoid any spill. Hospital policies to prevent spills should be adopted by the surgical and operation theatre team members and written procedures must specify the team responsible for spill management. Health care institutions should develop a plan and policy for handling hazardous medications. Collection, labeling, storage, transport, and disposal of contaminated waste should be done as per hospital policy.Cleaning the operating room after HIPEC: Soap water is adequate to clean the operating room after HIPEC three consecutive times. 70% of isopropyl alcohol is also safe and effective.Conclusions: All available studies point out that the correct use of specific protective measures is a key factor to minimize exposure. Emphasis has to be also placed on educating and instructing the involved personnel in the hazards and safe use of chemotherapy, the importance of adherence to safety protocols, and the correct use of the recommended personal protective equipment.

Measuring indoor fine particle concentrations, emission rates, and decay rates from cannabis use in a residence

Fifteen states have legalized the sales of recreational marijuana, and California has the largest sales of any state. Cannabis is most often smoked indoors, but few measurements have been made of fine particle mass concentrations produced by secondhand cannabis smoke in indoor settings. We conducted 60 controlled experiments in a 43 m 3 room of a residence, measuring PM 2.5 concentrations, emission rates, and decay rates using real-time monitors designed to measure PM 2.5 mass concentrations. We also measured the room's air exchange rate. During each experiment, an experienced smoker followed an identical puffing protocol on one of four different methods of consuming marijuana: the pre-rolled marijuana joint (24 experiments), the bong with its bowl containing marijuana buds (9 experiments), the glass pipe containing marijuana buds (9 experiments), and the commercially available electronic vaping pen with a cartridge attached containing cannabis vape liquid (9 experiments). For comparison, we used the same puffing protocol to measure the PM 2.5 emissions from Marlboro cigarettes (9 experiments). The results indicated that cannabis joints produced the highest indoor PM 2.5 concentrations and had the largest emission rates, compared with the other cannabis sources. The average PM 2.5 emission rate of the 24 cannabis joints (7.8 mg/min) was 3.5 times the average emission rate of the Marlboro cigarettes (2.2 mg/min). The average emission rate of the cannabis bong was 67% that of the joint; the glass pipe's emission rate was 54% that of the joint, and the vaping pen's emission rate was 44% that of the joint. The differences compared to the joint were statistically significant. • 60 experiments comparing indoor PM 2.5 from secondhand marijuana & tobacco smoke. • The marijuana joint's emission rate was 3.5 times that of the tobacco cigarette. • All the cannabis sources had PM 2.5 emission rates greater than tobacco cigarettes. • The order of cannabis emission rates was joint, bong, glass pipe, and vaping pen. • The vaping pen's mean decay rate exceeded the other sources' mean decay rates.

МЕСТНАЯ ВЫТЯЖНАЯ ВЕНТИЛЯЦИЯ С ЭЖЕКТИРОВАНИЕМ

Exhaust ventilation systems in industrial enterprises and facilities with the use of harmful substances largely determine the air exchange in the workplace to ensure normalized sanitary and hygienic conditions and operating costs. Local exhaust ventilation of explosive harmful substances is of particular importance for effective air exchange in such rooms, since their localization, suction and transportation are subject to increased requirements. The paper presents the results of analytical and experimental studies of the operation mode of a complex local exhaust device with a gas ejector for extraction explosive harmful chemicals from shelters, ensuring their effective localization, purification and recirculation of air. The boundary conditions and assumptions for calculating the characteristics of the processes of gas flow ejection, purification of technological emissions and recirculation of the purified gas flow, determined on the basis of the analysis of previously performed studies and experimental work, are given. The conditions of rational ratios device settings of extraction of emissions sources of substances that parameters of the ejector and cleaning device emission, which is achieved economic and environmental efficiency of the installation and excludes the volatile situation on the threat of chemical enterprises and objects.

Impact of fan mixing on air pollutant exposure near indoor sources: An analytical model to connect proximity effect with energy

Exposures close to indoor sources are substantially higher than further away. To predict this “proximity effect”, we must determine the human exposure modeling parameter - turbulent diffusion coefficient, and how important room-specific factors such as fan power influence it. We conducted 11 experiments in a residential garage and an office, varying the operating speeds of two household fans at a room corner to create a range of air mixing conditions. In each, SidePak monitors sampled PM2.5 every 10 s over ~2 h at 15–16 points at different horizontal distances and angles from an emitting tracer particle source near the room center. Using an analytical exposure model involving eddy diffusion, the turbulent diffusion coefficient was deduced from the spatial PM2.5 measurements. Values ranged from 0.001 to 0.012 m2/s for power inputs of 0–4 W. By factoring in the room dimensions and air exchange, we found a significant relationship between the turbulent diffusion coefficient and fan power input across the two rooms. The deduced relationship allows assessments of (i) the magnitude of the proximity effect and (ii) the energy budget for reducing exposure via air mixing for a given indoor setting; it can be applied for different air contaminants (e.g., gaseous pollutants) in indoor environments where turbulent mixing dominates over brownian diffusion. For rooms with low air exchange rates, a modest power input from a fan can greatly increase pollutant mixing, reducing proximity exposure with minimal energy consumption.

Nursing care for controlling coronavirus infections in positive cases: a narrative review

ObjetivoEsta revisión tiene como objetivo realizar un mapeado de evidencias científicas en cuidados enfermeros dirigidos a controlar infecciones por coronavirus.MétodoSe llevó a cabo una búsqueda bibliográfica en las bases de datos Medline, CINAHL, Scopus y en la colección principal de la WOS, sin límite de fecha y a través de las palabras clave «transmission», «infection», «contagious», «spreads», «coronavirinae», «coronavirus», «covid 19», «sars cov 2», «nurses» y «nursing». Inicialmente se identificaron 154 estudios y, tras seleccionarlos según criterios de elegibilidad, se incluyeron 16.ResultadosEntre las recomendaciones principales, según la evidencia disponible, se encuentran el intercambio de aire en las habitaciones como medida para reducir el riesgo de contagio entre pacientes; el refuerzo de medidas en unidades de cuidados intensivos; seguimiento de contactos de casos positivos; y una adecuada formación de los profesionales.Discusión y conclusionesLos estudios incluidos en la revisión trataron sobre prácticas de prevención y control de contagios, analizando riesgos asociados a la exposición y enumerando acciones para evitar complicaciones en pacientes críticos. Se identificaron patrones de transmisión de casos, contactos y factores asociados. También se estudiaron los conocimientos y actitudes profesionales, mostrando la importancia de una buena formación para el control de infecciones, y de disponer de equipos suficientes y adecuadas infraestructuras.Las enfermeras son vectores importantes de propagación. A pesar de que la evidencia disponible sobre la efectividad de cuidados para evitar el contagio por SARS-CoV-2 es escasa, los estudios publicados sobre la prevención y control ante brotes anteriores por coronavirus son de considerable utilidad.

Study of aerodynamics of stream flow in server rooms using numerical modeling

This paper analyzes various schemes of air exchange in server rooms. Top-down and down-top vertical cooling schemes for small server rooms using local AC systems were analyzed. Numerical models were developed for the study of heat and mass transfer and server aerodynamics, which make it possible to evaluate the cooling efficiency of electronic equipment when placed in an arbitrary configuration. To study the thermal and velocity fields, numerical simulation of the stream flow processes was performed using the FlowVision software. This paper shows the advantage of the selected air-conditioning scheme compared to the existing ventilation system. Modeling results may be used for designing small server rooms.

Analytical description of the expansion of wall jets of different curvature

The work is devoted to an analytical study of the expansion of wall jets on a convex and concave surfaces (curved semi-limited jets). Such jets have different characteristics depending on the curvature of the surface - from long-range to fast-decay. This makes them one of the most promising areas of increasing the efficiency of air exchange in rooms for various purposes. However, today they have not widespread introduction, which is because of the instability of the development of the jets. The problem is eliminated by using the correct shape of the air outlet duct. To determine the expansion of the jet, an approach has been developed to the analytical description of curved wall jets using the geometric analysis of their turbulent macrostructure. This structure is represented in the form of a sheetof tangent large-scale vortices (puffs). To effectively solve the obtained equations, the Anderson-Björk method was improved. The results show a slight expansion of concave jets and much faster for convex ones. Calculations showed the presence of a critical section with the rapid expansion of a convex jet and the subsequent increased rate of its expansion. Also, a cross section for separation of the jet is obtained. If the slot width is less than 0.15 ... 0.2 of the radius of the wall, then the angle of passage of the jet is significantly reduced, which reduces the expansion of the jet and complicates the design of the multi-slot air distributors developed at the Department of Heat and Gas Supply and Ventilation of Kiev National University of Construction and Architecture.

Ensuring Room Air Exchange for Exercises

This paper presents the documentary part of the study of the effect of human physical activity on the microclimate of the premises. In gyms, ventilation requirements are higher than in conventional living quarters. Today, a lot of attention is paid to a healthy lifestyle. In cities where the environment is polluted with exhaust gases of vehicles, it is not recommended to go in for sports in urban parks. For this reason, a variety of simulators, including cycling, are used. When using simulators, indoor air quality deteriorates. The purpose of the study is to determine the amount of pollutants released in the room by means of experimental measurements and calculations, as well as determination of the required air exchange on the basis of the determined quantities. Such low quality of the internal environment can cause a decrease in human productivity, drowsiness, fatigue, and may also be the cause of various diseases. In this paper, an experimental measurement is documented, during which various motor activities of one person took place – sedentary administrative activity and exercise bike. Experimental measurements took place in two stages in winter. On the basis of the measured internal air parameters, the required airflow is calculated for both cases. Measured indoor air parameters (temperature, relative humidity and carbon dioxide concentration) are documented in figure. Estimates can be used to select equipment for conditioning in gyms. On the basis of experimental measurements, we argue that the CO2 concentration increases by 3.2 times in the case of a stationary exercise bike compared to sitting work. However, atmospheric air (m3 / year) – 5 times more.

The use of slotted – displacement ceiling diffuser in rooms with stationary workplaces with computer equipment

This paper presents a specification of premises with a stationary workstations. An analysis of thermal loads occurring in a public utility rooms equipped with a computer, electronic and multimedia equipment was carried out. Attention was drawn to an annual occurrence of a positive heat balances in an occupied workstations and heat losses in winter time in unoccupied premises. For an air distribution a slotted displacement ceiling diffuser was proposed, used for mixing ventilation (MV) in up-up type of air exchange in room. The results of measurements in the form of air flows in the area of its operation are provided. The graphs show the graphical distribution of air velocities and temperatures in the vertical plane passing through the transverse axis of the air diffuser. The study focused on one of the representative airflow of supply air and the behaviour of the air stream during heating and cooling was presented.

Inhalation Exposure and Respiratory Protection of Home Healthcare Workers Administering Aerosolized Medications (Simulation Study)

ABSTRACT There is little information regarding aerosol exposure from using medical nebulizers and the factors affecting the risk of exposure, especially for treatments performed in a patient’s home environment. Home healthcare workers (HHWs) are a rapidly growing work population often exposed to aerosol hazards. Thus, we designed a simulated environment to measure the aerosol inhalation exposure of an HHW administering pressure-nebulized medications. We determined the relative contributions of different factors to aerosol reduction, namely, the room air exchange rate, proximity to the patient, and patient breathing rate, in an exposure chamber simulating a patient’s bedroom. Additionally, the performance of respiratory protective devices worn by an HHW, a surgical mask and N95 filtering facepiece respirator (FFR), was evaluated using NaCl as a well-established surrogate. The particle concentration in the breathing zone of an unprotected worker ranged from 7,118 to 284,600 cm–3. The proximity to the aerosol source affected the aerosol concentration, but the influence of this factor diminished when the distance increased beyond 24 inches. For an unprotected HHW, ventilation was the most effective way to reduce exposure to nebulizer-produced medical aerosols. An increase in the air exchange rate from 0 to 5 h–1 significantly reduced the exposure; however, a further increase (to 17 h–1) produced only a small reduction in the particle concentration. Therefore, no evidence suggests that patient homes require extremely efficient ventilation to mitigate HHWs’ exposure to nebulizer-produced medications. Increasing the patient’s breathing flow rate reduced the aerosol inhalation exposure; however, this factor cannot be controlled, which weakens its practical viability. Wearing respiratory protection devices was found to be the most efficient way to reduce aerosol exposure (within the set of tested variables). As expected, an N95 FFR with a proper seal was about 20-fold more efficient than a surgical mask.

Introduction of Norms for Air Exchange in Rooms and Energy Efficiency of Residential Buildings

Energy saving policy conducted all over the world and in Belarus, particularly, leads to revision of technical standard and legal acts on thermal protection of buildings. Gradual increase of resistance to heat transfer of enclosing structures reduces transmission heat losses however expenses on infiltration air heating remain unchangeable. Due to this their portion in overall heat balance of residential buildings is gradually increasing: up to thermal rehabilitation of a building the portion constitutes 30 %, after this process the portion is equal to 53 %. In order to find methods for reduction of heat losses the paper considers an origin of the current standard for inlet air which is equal to 3 m³/h per 1 m² of residential area. It has been shown that the given value has been determined on the assumption of air exchange which is required for assimilation of carbon dioxide and residential area standard per one person. The required air exchange can be reduced up to 1.5 m³/(h×m²) due to improvement of population living conditions and increase in provision of residential area. Calculations have also shown that the given reduction makes it possible to enhance energy efficiency class of a building and decrease portion of heat losses on heating inlet air in overall heat balance. The paper has also revealed that rational light location on both sides permits to reduce a specific index of heat energy consumption for heating and ventilation of a residential building. Determination of outlet air consumption for kitchens has been considered simultaneously with determination of inlet air consumption. It has been ascertained that in order to support combustion process and removal of combustion products consumption of outlet air must constitute 10–20 m³/h according to type of gas stove. Due to the fact that windows can not support the proposed and existing air exchanges they must be completed with plenum valves.

The slotted – displacement ceiling diffuser as an alternative to the organization of down – up air exchange in rooms with computer equipment

The article analyses heat loads occurring in public utility rooms with computer or multimedia equipment. Attention has been paid to the possibility of using down – up type (displacement ventilation, DV) and up – up type (mixing ventilation, MV) of air exchange. The design of the slotted – displacement ceiling diffuser is presented. The results of measurements in non-isothermal conditions in the form of air flows in the area of its operation are provided. The graphs show the graphical distribution of velocities and air temperatures in the vertical plane passing through the transverse axis of the special diffuser. The study of the behavior of the stream flowing out of the diffuser was only in the scope of work. The velocity and air temperature distribution over the heat sources, which were located away from the diffuser, next to the external walls, was not studied. The focus was on three representative airflows of supply air and the behaviour of the air stream during cooling was presented.

On some aspects of modernisation of a wooden house with special cultural value

This paper presents specification of the scope of modernization of a wooden house built in 1950 in the village of Nowoberezowo in the Podlaskie voivodship (eastern Poland). It was constructed in traditional technology that is specific for this area and which dates back to the 19th century. It was considered that due to special cultural values it is necessary to preserve the exterior appearance of the building. For this reason, the idea of insulating its external walls from the outside was abandoned. In connection with planned interior remodelling and the selected variant of insulation of external walls from the inside, a hydrothermal analysis was carried out. On this basis, the maximum acceptable thickness of the thermal insulation layer was determined given the need to protect wood against degradation resulting from long-lasting moisture. The necessity to ensure adequate air exchange in rooms was emphasized and a mechanical ventilation system was proposed. Next, the impact of the proposed treatments on the change of energy performance was evaluated. An economic assessment was also made and a simple payback time was determined.

Impact of Outdoor Air Exchange Rates on Sleep Quality and the Next-Day Performance with Application of Energy Recovery Ventilator

Sleep quality can affect human health and the next-day performance. High indoor CO2 concentration levels due to insufficient supplied air ventilation could cause poor sleep quality. Bedrooms in condominium in Thailand commonly use a wall mounted split type system without supplied outdoor air ventilation. The rooms are typically constructed having airtight envelope which have air infiltration rates ranging 0.4-0.64 ACH. This study aims to evaluate the impact of increased ventilation rates on sleep quality and the next-day performance, which the surveys were collected from two occupants living in a one bedroom condominium. The field measurement and survey were conducted for twenty days with supplied outdoor airflow rates at 0, 40, and 60 m3 hr-1 through an energy recovery ventilator (ERV). The room air exchange rates were calculated from a linear regression method obtained from a decay tracer gas technique using indoor carbon dioxide generated by occupants. To overcome the maximum limit of CO2 concentration level specified in the standard health guidelines, the ERV unit has to supply outdoor air ventilation rate at 60 m3 hr-1. Overall, the increase of outdoor air ventilation rates can improve sleep quality by 2-13 percent and occupants have better work performance in the next day by 2-20 percent. The increase of outdoor air ventilation through the ERV unit does not affect indoor relative humidity.

Lagrangian Coherent Structures for Design Analysis of Revolving Doors.

Room air flow and air exchange are important aspects for the design of energy-efficient buildings. As a result, simulations are increasingly used prior to construction to achieve an energy-efficient design. We present a visual analysis of air flow generated at building entrances, which uses a combination of revolving doors and air curtains. The resulting flow pattern is challenging because of two interacting flow patterns: On the one hand, the revolving door acts as a pump, on the other hand, the air curtain creates a layer of uniformly moving warm air between the interior of the building and the revolving door. Lagrangian coherent structures (LCS), which by definition are flow barriers, are the method of choice for visualizing the separation and recirculation behavior of warm and cold air flow. The extraction of LCS is based on the finite-time Lyapunov exponent (FTLE) and makes use of a ridge definition which is consistent with the concept of weak LCS. Both FTLE computation and ridge extraction are done in a robust and efficient way by making use of the fast Fourier transform for computing scale-space derivatives.