Air Infiltration Research Articles

Experimental study on energy consumption and thermal environment of radiant ceiling heating system for different types of rooms

This paper investigates energy consumption and thermal environment performance of a radiant ceiling heating system serving different types of rooms in the same building. Four types of rooms with different functions, namely restaurant, office, flight control room, and conference room, were chosen in this study. Energy consumption and thermal environment parameters were measured in different rooms, including the heating energy consumption intensity, indoor air temperature, surface temperature of the building envelope, air temperature stratification, and vertical temperature gradient. The results show that the heating energy consumption intensity is about 19.63 W/m2, which is about 30% lower than the heating index recommended in the regional standard. The heating indexes per unit area of the restaurant, office, flight control room, and conference room are 33.41, 17.36, 18.91, and 20.32 W/m2, respectively. The unit volume heating energy consumption of the flight control room, which is a large space, is significantly lower than that of the office, which is a small space. Moreover, there are also differences regarding the indoor thermal environment of the different types of rooms. Factors such as solar radiation, outdoor cold air infiltration, and indoor occupancy rate are the main factors that influence the indoor thermal environment. In general, the energy consumption level of radiant ceiling heating systems for larger spaces is lower, and the indoor thermal environment is better. Therefore, radiant ceiling heating systems are more suitable for larger rooms.

Impact of atmospherical stability and intra-hour variation of meteorological data in the variability of building air change rates

In contrast with structural engineering, where the focus for design is on extreme values, for the proper assessment and modelling of air change rates in natural ventilation and infiltration, one must use the full range of input variables. Most of the modelling in infiltration research relies on hourly datasets for air infiltration balance. This consideration overlooks the intra-hour variability on meteorological variables. Additionally, it is customary to assume unchanging neutral atmospheric conditions when modelling, which affects the calculated airflows. This work intends to detail and quantify these effects in a case study representative of an average single-family dwelling in a Southern European climate setup. By comparing four setups with an increasing degree of complexity, a median of 0.04 h−1 of the hourly standard deviations in air change rates (ACH) is attributed to the time step effect. Approximately 43% of the occurrences experienced non-neutral atmospheric stability, skewing for stable conditions. This effect contributed to differences in the ACHs ranging from −0.202 to 0.131 h−1 at the 5% and 95% quantiles. Overall, by using hourly uniform distributions and smart sampling of meteorological variables, one ensures that the values in between and others potentially occurring around the boundaries are being considered for air change rates calculation, and therefore providing a more detailed picture of actual conditions.

The retrofit of ‘70s office buildings curtain walls in London

The built environment accounts for 44% of UK emissions, of which 18% are from non-domestic buildings. Considering that a façade's performance accounts for more than 50% of the energy consumption of a building, the retrofit of a ‘70s curtain wall system is analysed along with common issues such as poor insulation, fire risk, air infiltration and absence of natural ventilation, all of which are known to affect both occupants’ comfort and energy demand negatively. The methodology includes thermal and energy analysis of the Euston tower, results from which are used to inform an analytical model representing a more extensive building stock. Orientation, occupation, window to wall ratio and floor heights are examined as the main factors influencing heat gains, and different passive design solutions are tested to reduce them. Combining these passive design strategies shows a reduction of cooling demand by up to 91% and overheating hours down to 0% from base case to best case, demonstrating how the retrofit of curtain walls in office buildings is essential to cut emissions, reducing energy demand and improving comfort and productivity.

Use of Beta Regression to investigate the link between home air infiltration rate and self-reported health

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.

Application of dehumidification as anti-corrosion technology on suspension bridges: A review

• Dehumidification is a proactive corrosion protection for suspension bridges’ main cable. • A review on different dehumidification systems on suspension bridges. • Discussion on limitations and adaptations for main cable anti-corrosion application. • Identifying future scenarios and challenges of dehumidification on suspension bridges. The moisture from residual droplets during construction and infiltration of wet air during operation can cause metal corrosion of main cables on suspension bridges. Main cable dehumidification, emerged as a prospective corrosion protection approach, which provides an internal environment of relative humidity below 60%, would significantly mitigate the corrosion. This paper presents a state-of-the-art listicle review of existing dehumidification systems implemented on 47 suspension bridges (e.g., the Akashi Kaikyo Bridge, the Runyang Yangtze River Bridge). Dehumidification methods adopted in suspension bridges, including solid desiccant dehumidification, condensing dehumidification and integrated dehumidification, are elaborated. Based on that, crucial limitations and adaptations of various systems for main cable applications are discussed. Then, technical suggestions concerning the moisture load matching, sensor configurations, full-bridge sealings, dehumidification equipment placement and system division, are given to realize system sustainability and energy efficiency. Finally, this paper examined one potential development of a multi-stage dehumidification system that uses condensing dehumidification and solid desiccant dehumidification, which facilitates cascade utilization of the waste energy and enhances the system efficiency.

Evaluating methods for estimating whole house air infiltration rates in summer: implications for overheating and indoor air quality

PurposeAccurate values for infiltration rate are important to reliably estimate heat losses from buildings. Infiltration rate is rarely measured directly, and instead is usually estimated using algorithms or data from fan pressurisation tests. However, there is growing evidence that the commonly used methods for estimating infiltration rate are inaccurate in UK dwellings. Furthermore, most prior research was conducted during the winter season or relies on single measurements in each dwelling. Infiltration rates also affect the likelihood and severity of summertime overheating. The purpose of this work is to measure infiltration rates in summer, to compare this to different infiltration estimation methods, and to quantify the differences.Design/methodology/approachFifteen whole house tracer gas tests were undertaken in the same test house during spring and summer to measure the whole building infiltration rate. Eleven infiltration estimation methods were used to predict infiltration rate, and these were compared to the measured values. Most, but not all, infiltration estimation methods relied on data from fan pressurisation (blower door) tests. A further four tracer gas tests were also done with trickle vents open to allow for comment on indoor air quality, but not compared to infiltration estimation methods.FindingsThe eleven estimation methods predicted infiltration rates between 64 and 208% higher than measured. The ASHRAE Enhanced derived infiltration rate (0.41 ach) was closest to the measured value of 0.25 ach, but still significantly different. The infiltration rate predicted by the “divide-by-20” rule of thumb, which is commonly used in the UK, was second furthest from the measured value at 0.73 ach. Indoor air quality is likely to be unsatisfactory in summer when windows are closed, even if trickle vents are open.Practical implicationsThe findings have implications for those using dynamic thermal modelling to predict summertime overheating who, in the absence of a directly measured value for infiltration rate (i.e. by tracer gas), currently commonly use infiltration estimation methods such as the “divide-by-20” rule. Therefore, infiltration may be overestimated resulting in overheating risk and indoor air quality being incorrectly predicted.Originality/valueDirect measurement of air infiltration rate is rare, especially multiple tests in a single home. Past measurements have invariably focused on the winter heating season. This work is original in that the tracer gas technique used to measure infiltration rate many times in a single dwelling during the summer. This work is also original in that it quantifies both the infiltration rate and its variability, and compares these to values produced by eleven infiltration estimation methods.

REDUCTION OF UNPRODUCTIVE HEAT CONSUMPTIONS OF PASSENGER ROLLING STOCK IN THE HEATING PERIOD

Passenger rolling stock is an important component of passenger transportation services, which should ensure not only traffic safety, but also comfortable transportation conditions. Studies on the energy saving of railway rolling stock have revealed shortcomings in the operating documentation that increase the unproductive consumption of thermal energy by passenger cars during the operation of a heating system with a combined electric-coal boiler in electric heating mode. Experimental measurements confirmed the presence of unproductive losses of thermal energy through the intake blinds of the ventilation system due to the infiltration of outside air during downtime at the points of formation and turnover of passenger cars. Also, experimental measurements showed that there is a leak of warm air through the deflectors to remove exhaust air from the car into the environment. This is their regular mode of operation, but as highlighted in the author's early publications there are two zones of temperature fields in the body of the passenger car with different temperature regimes, which are separated by a decorative ceiling. The results show that the leakage of warm air through the deflectors occurs from the temperature field zone with a higher temperature, which increases the unproductive consumption of thermal energy. Thus, by making appropriate changes to the operating documentation based on the study, the energy efficiency of passenger rolling stock will be greatly improved in its further operation. In particular, it is established that the proposed modernization in order to increase the energy efficiency of the heating system can be carried out at relatively low cost, in modern car repair depots during overhauls, and also needs to be considered when designing new passenger cars.

Design of drain tube with movable shutter in household refrigerators

• Infiltration of warm and humid air to the freezer results in frost accumulation. • For reduction of inflow, drain tube with a high hydraulic resistance is proposed. • Negative pressure is formed by air shrinkage after door opening and closing. • To release the negative pressure, the proposed drain tube has a movable shutter. • Movable shutter can control air vents depending on the pressure condition. The infiltration of warm and humid air from the outside into a freezer results in frost accumulation around the evaporator in household refrigerators. This can significantly reduce the cooling capacity of refrigerators. In this study, the pressure, temperature, and frost around a proposed drain tube were monitored through in-situ measurements until the first defrost process (about 54 h). The proposed drain tube has 220 times higher hydraulic resistance and shows 55 times lower inflow in computational fluid dynamics (CFD) analysis. Once the door of the freezer compartment is opened and closed, external warm air replaces the cold air in the freezer. Negative pressure is produced by the shrinkage of this external air under low-temperature conditions. The other role of the drain tube is to vent air between the outside and inside of the refrigerator under negative pressure. To release the negative pressure, the proposed drain tube has a movable shutter. In the CFD results, the secondary inlet increases the inflow by 3.2 times compared to the inflow in an I-type tube. To determine the design, the weight and inner diameter of the drain tube were changed. The performance of the proposed tube was validated by the lack of blockage of discharge until the first defrost process. The movable shutter did not allow the negative pressure to exceed -100 Pa by facilitating air venting after opening the door for 10 seconds and then closing it.

DEBILITATING SUBCUTANEOUS EMPHYSEMA IN THE SETTING OF RESOLVING SECONDARY PNEUMOTHORAX

TOPIC: Disorders of the Pleura TYPE: Medical Student/Resident Case Reports INTRODUCTION: Subcutaneous emphysema (SE) is defined as the presence of air under subcutaneous tissues manifesting as swelling and crepitus. This typically benign self-limiting condition can rapidly deteriorate if left unchecked. We present a case of debilitating SE in the setting of pneumothorax management. CASE PRESENTATION: A 72-year-old man with severe chronic obstructive pulmonary disease presented with an iatrogenic small right-sided pneumothorax immediately after CT-guided biopsy of a pulmonary nodule. He improved after right thoracostomy tube insertion. Twenty-four hours after removal of the tube, he experienced dyspnea and chest pain. Physical exam was pertinent for absent breath sounds on the right hemithorax. A new moderately sized right sided lateral pneumothorax was noted on emergent chest x-ray. Due to worsening respiratory failure, he underwent intubation prior to being transferred to the intensive care unit. Upon chest tube placement, he was noted to have extensive crepitus on the bilateral neck, right hemithorax, abdomen, and pelvis. He was successfully extubated and repeat imaging confirmed resolution of pneumothorax with complete lung re-expansion, thus the chest tube was shifted from suction to water seal. Five minutes after, the subcutaneous emphysema rapidly progressed to involve the entire face as evidenced by worsening bilateral periorbital edema, closure of palpebral fissures, and high patient distress. Infraclavicular blowhole incisions were then placed and the chest tube was placed back on 20 mmHg suction. He was continued on suction for three more days until eventual resolution of the subcutaneous emphysema. DISCUSSION: SE is defined as de novo infiltration of air in the subcutaneous layers of the skin. Potential causes include surgeries, trauma, infections, and idiopathic etiology, with an incidence of 0.43% to 2.34%. Complications of extensive SE include dysphagia and compression of the airway, barotrauma, expanding pneumothorax, reduced cardiac preload, skin necrosis, amongst others. Debilitating features include anxiety, dysphagia, dysphonia, and significant respiratory or circulatory compromise. Our patient had a higher risk for SE due to the timing of the thoracotomy tube insertion while the patient was exposed to positive pressure. Worsening of the SE was due to premature discontinuation of chest tube suction. Although the pneumothorax has already resolved, it is prudent to delay transitioning the suction to water seal until the SE has stabilized. Infraclavicular blow-hole incisions, subcutaneous drains, fenestrated angiocatheters, vacuum assisted dressings and increasing suction on a pre-existing chest tube have also been described to expedite the time to recovery from debilitating SE CONCLUSIONS: Early identification and management are essential to decrease SE-related complications and mortality. More studies are needed to explore ideal management options. REFERENCE #1: Aghajanzadeh M, Dehnadi A, Ebrahimi H, Fallah Karkan M, Khajeh Jahromi S, Amir Maafi A, Aghajanzadeh G. Classification and Management of Subcutaneous Emphysema: a 10-Year Experience. Indian J Surg. 2015 Dec;77(Suppl 2):673-7 REFERENCE #2: Maunder RJ, Pierson DJ, Hudson LD. Subcutaneous and mediastinal emphysema. Pathophysiology, diagnosis, and management. Arch Intern Med. 1984 Jul;144(7):1447-53 REFERENCE #3: Jones P, Hewer R, Wolfenden Het al. Subcutaneous emphysema associated with chest tube drainage. Respirology 2001; 6(2): 87–89 DISCLOSURES: No relevant relationships by Gustavo Avila, source=Web Response No relevant relationships by Jessica Baek, source=Web Response No relevant relationships by Renuka Reddy, source=Web Response No relevant relationships by Jodi Renner, source=Web Response No relevant relationships by Larnelle Simms, source=Web Response No relevant relationships by Laura Suzanne Suarez, source=Web Response No relevant relationships by Claudia Tejera Quesada, source=Web Response

Experimental analysis and quantification of air infiltration into a passenger car cabin

Nowadays, air quality in closed environments is of major interest, particularly in very small volumes such as car cabins. In typical driving conditions, ambient air enters by infiltration as the vehicle speed increases. In order to satisfy more ambitious requirements on air quality and energy savings, it is necessary to evaluate the infiltration risk. At first, an experimental method is created to identify the infiltration path in the cabin of a moving car. On a modern electric vehicle, the privileged path is observed at the front of the cabin near the feet of the front passengers. A second experimental campaign is performed to quantify the infiltration flow rate. Results show that the flow rate is not negligible as it can reach several dozen kilograms per hour. The ventilation settings (blower speed and recirculation ratio) can be managed to reduce or even completely remove infiltration in some cases.

Study on pressure control and energy saving of cleanroom in purification air conditioning system

Pressure control for cleanrooms in the pharmaceutical industry is a necessary means to avoid the cross-contamination. The pressure control of traditional air conditioning can only handle the working stage. In the non-working stage, the system cannot reduce the air change rate per hour (ACH) in order to alleviate the problem of high energy consumption. This paper proposes an improved air conditioning system, which focuses on the ability to control pressure gradient of the system in working and non-working mode. By theoretical derivation of the combined fan frequency conversion, when the impedance and volume of the infiltration air satisfy SiGZ,i=SjGZ,j=SkGZ,k=constant, the pressure gradient in multi-zone cleanrooms can remain stable. A mathematical model of the system has been established, which includes five modules: air pipe network, fan characteristic curve, fan operating point solution, variable volume damper characteristic curve and multi-zone network pressure gradient solution. The correctness of the model is verified by field measurements. Taking a clean workshop as case study, the room pressure can be stabilized in the range of ± 3 Pa by switching the working and non-working mode, which can save 39.8% of the energy consumption in non-working mode, while ensuring cleanliness. This paper demonstrates the process of the air pipe network’s influence on cleanrooms pressure and proves the effectiveness of improved purification air conditioning system in pressure gradient control and energy saving potential.

An inquiry into the use of indoor CO2 and humidity ratio trend data with inverse modelling to estimate air infiltration

Air infiltration has a significant impact on building energy performance and the indoor environment. An accurate estimate of air infiltration rate informs envelope retrofit decisions to improve airtightness. However, air mobility and other environmental factors, such as wind or indoor-outdoor temperature differences, often make the accurate measurement of air infiltration challenging. Further, conventional air infiltration testing approaches such as fan pressurization and tracer gas tests possess certain drawbacks limiting their applicability in commercial buildings. To address the limitations of air infiltration tests, this study proposes a low-cost inverse model-based approach for estimating air infiltration rates by extracting the naturally occurring indoor CO2 and relative humidity (RH) data from a building automation system (BAS). These data were used to develop a linear regression model, and a tracer gas experiment was also used to verify the applicability of the proposed approach. The results indicated that the proposed method could conveniently lend itself to estimate air infiltration rates at a reasonable accuracy using existing CO2 data; however, humidity ratio data (converted from RH and temperature sensor measurements) may only help to track building infiltration characteristics over time due to inaccuracies caused by adsorptive and desorptive properties of various building materials.

Coupling effect of building design variables on building energy performance

In this paper, the coupling effect of building design variables on building energy performance was studied by taking office in hot summer and cold winter zone as an example. The Latin hypercube method was introduced to sample the architectural design features under different combinations of 10 variables, and simultaneously, the simulations on energy consumption were conducted through Energyplus. The potential interaction effect between design variables were analysed by using treed Gaussian process. Meanwhile, the coupling effect of these variables was further analysed quantitatively by using interaction in linear regression. The study showed that the coupling effect of the design variables and their impact on energy consumption trends could not be revealed by ordinary linear regression. Besides, the influence of interactions between design variables on energy consumption needs to be taken into account. The coupling relationships were found amongst the windows' heat transfer coefficient, the window-to-wall ratio, and the air infiltration. Therefore, these parameters should be selected properly based on the features of energy consumption and coupling variables. Furthermore, it was recommended to consider summer heat insulation/dissipation when the window-to-wall ratio is large in this district, instead of strengthening heat preservation.

Energy & Thermal Comfort Performance using EnergyPlus® for a Single-Family Residency located in Foz do Iguaçu, Climatic Zone 3A-Brazil

Energy performance and thermal comfort through EnergyPlus®, for a prototype of a single-family residence located in Foz do Iguaçu,climate zone 3A-Brazil. Using the estimated thermal sensation inside the house, natural ventilation was analyzed, where a system was compared considering the air infiltrations of the construction model with another of programmed selective ventilation; and two heating,ventilation, and air conditioning (HVAC) systems were proposed, being a Split system and a variable refrigerant gas flow (VRF) system.The results showed that, although the cases of natural ventilation influenced internal temperature and humidity, thermal comfort in the region is not feasible without the use of artificial mechanisms. The VRF system showed annual energy saving to the air conditioning of 14.76% and saving in the total annual energy consumption of 10.11% about the Split system, in addition to more economic profitability.

Comparative Modelling Analysis of Air Pollutants, PM2.5 and Energy Efficiency Using Three Ventilation Strategies in a High-Rise Building: A Case Study in Suzhou, China

This study investigated the ventilation efficiency and energy performance of three ventilation strategies—an all-air system (AAS), a radiant panel system with a displacement ventilation system (DPS), and a radiant panel system with a decentralized ventilation system (DVS). The research analyzed the indoor air quality (IAQ) in a high-rise building based on the building’s height, the air handling unit (AHU) location, air infiltration rate, outdoor air pollution rate, seasonal change, and air filter efficiency. The results indicated that the AAS had the best performance in terms of IAQ in the high-rise building in winter; however, the AAS also had the highest annual energy demand. For the same conditions, the DVS consumed less energy but had the worst performance in maintaining a satisfactory IAQ. Considering energy consumption, it is worth developing the DVS further to improve ventilation performance. By applying a double-filter system on the lower floors in a high-rise building, the DVS’s ventilation performance was dramatically improved while at the same time consuming less energy than the original DPS and AAS. The application of DVS can also minimize the negative effect of the infiltration rate on indoor air quality (IAQ) in a building, which means that the DVS can better maintain IAQ within a healthy range for a more extended period. Moreover, it was found that the DVS still had a substantial potential for saving energy during the season when the outdoor air was relatively clean. Hence, it is highly recommended that the DVS is used in high-rise buildings.

Revised Zero-Dimensional Model for a Solid Oxide Fuel Cell with Mo-Doped Ceria Anode Using Syngas as Fuel

A zero-dimensional model was implemented to simulate the performance of a solid oxide fuel cell (SOFC) with Mo-doped ceria (CMO) anode using humidified (3%v/v water) hydrogen or syngas (50%v/v H2 – 50%v/v CO) as fuel. The model was validated preliminarily through experimental data generated at 800ºC using a SOFC with coated electrodes supported in the electrolyte (a 20 mm diameter yttria-stabilized zirconia, YSZ, disc) with a 14 mm diameter CMO|CMO-YSZ anode and a 14 mm diameter LSM-YSZ|LSM (lanthanum strontium manganite) cathode. Polarization (cell voltage vs current density, ΔEcell vs j) and power density (power density vs current density, Pelec vs j) curves were generated via linear sweep voltammetry connecting the SOFC to a Gamry Reference 3000 potentiostat/galvanostat/ZRA using platinum mesh and wires.The open circuit voltage (OCV) of the SOFC operating with humidified hydrogen was modelled directly using Nernst equations for the electrochemical hydrogen oxidation and oxygen reduction reactions. For the case of the SOFC operating with humidified syngas, the electrochemical hydrogen and carbon monoxide oxidation reactions occur simultaneously at the anode. Hence, the Nernst equation was corrected by each anodic reaction selectivity determined solving mass balances coupled to an electrochemical kinetics model.Figure 1.a shows the fitted polarization and power density curves. Maximum SOFC power densities of ca. 1295 W m-2 (at 0.53 V and 2434 A m-2) and ca. 1084 W m-2 (at 0.52 V and 2106 A m-2) are predicted for the cell operating with humidified hydrogen and humidified syngas as fuel, respectively. These values are 2 and 5% lower than the experimental values. The OCVs calculated are ca. 1.10 V and 1.01 V, respectively, which are 5 and 8% higher/lower than the experimental values. The differences observed are attributed to the non-ideality of the gases due to their interaction with the electrode surfaces, and the possible infiltration of air into the anodic chamber [1,2].The SOFC ohmic losses calculated represent ca. 72% of the total voltage losses when operating at the maximum power density, which are attributed to the low electrical conductivities of the CMO|CMO-YSZ anode (CMO electrical conductivity is ca. 0.501 S m-1 at 800ºC [3]) and the thick electrolyte (ca. 2.203 S m-1 at 800ºC [4]). Improvements are being introduced to the anode material by including nickel, which will contribute to increase the hydrogen oxidation kinetics while CMO protects the electrode from carbon deposition when syngas is used as fuel. Presently, activation losses represent ca. 28% of the total voltage losses at the maximum power density. It has been reported that for SOFCs using syngas as fuel, the anode active sites are more occupied by carbon monoxide molecules due to their slower oxidation kinetics in comparison with hydrogen. Nevertheless, carbon monoxide is also susceptible to undergo a surface reforming process via the water-gas shift reaction. Such phenomenon becomes more relevant at high carbon monoxide concentrations, which was the case in this study (50% v/v CO), thus favoring the electricity generation through hydrogen oxidation at the anode surface [2].For the SOFC using humidified syngas as fuel, the model assumes that the desorption equilibrium pressure of hydrogen (pH2 *) on the surface of molybdenum in the CMO|CMO-YSZ anode is equal to that reported for humidified hydrogen on the surface of nickel in Ni-YSZ anodes (0.09 atm) [5]. Figure 1.b shows the results obtained for the sensitivity analysis of the model as a function of pH2 *, which indicates that unless its value is increased by ca. 220% over 0.09 atm the exchange current density for carbon monoxide oxidation (j0,CO) does not go below its lower confidence limit. It is unlikely that this parameter reaches such level of discrepancy because it implies that hydrogen adsorption at the anode surface is strongly diminished, thus electrochemical oxidation kinetics decrease considerably which is not consistent with the experimental observations.Future work includes the analysis of the kinetic parameters dependence on the temperature and the fuels partial pressures.

KEANEKARAGAMAN DAN KEGUNAAN TUMBUHAN BAWAH PADA BEBERAPA TEGAKAN DI ARBORETUM BALAI PENELITIAN DAN PENGEMBANGAN TEKNOLOGI SERAT TANAMAN HUTAN (BP2TSTH) KUOK

Underground plants have an important role in soil and air conservation efforts, namely as a source of organic matter, preventing erosion, a source of germplasm and increasing air infiltration into the soil. This study aims to identify the types, diversity and use of understorey under stands of meranti, gaharu and mixed stands in the arboretum of the Kuok Forest Plant Fiber Technology Research and Development Institute (BP2TSTH). The data collection method used systematic sampling with a random start, with a sampling intensity of 5%. The number of plots observed for meranti, gaharu and mixed stands were 50, 25 and 25, respectively, with a plot size of 2 x 2 (m). In the stands were found 17 families of undergrowth consisting of 23 species and 10,338 individuals. In the agarwood stands there are 10 families of undergrowth consisting of 13 species and 9,696 individuals. In the agarwood stands there are 11 families with a diversity of 13 species and 10,328 individuals. Diversity Index and Evenness Index in meranti, gaharu and mixed stands respectively; 1.25 and 0.4; 0.72 and 0.28; 0.72 and 0.28. Paspalum conjugatum is a understorey species with the highest Importance Value Index (IVI) in the three stands.

Effect of Roof Cooling and Air Curtain Gates on Thermal and Wind Conditions in Stadiums for Hot Climates

To host the 2022 FIFA World Cup, Qatar is facing the greatest challenge in balancing the energy consumptions for cooling the stadiums and the thermal comfort for both players and spectators. Previous studies have not considered using a combined configuration of air curtain and roof cooling supply slot in stadiums to prevent the infiltration of outside hot air and reduce the cooling system’s energy consumption. This paper presents a Computational Fluid Dynamics (CFD) study of thermal and wind modeling around a baseline stadium and simulates the cooling scenarios of air curtains and roof cooling along with the energy consumption estimations for the World Cup matches using Building Energy Simulation (BES). Sensitivity analysis of different supply speeds and supply temperatures of air curtain gates and roof cooling was carried out, and the results showed that scenario six, which provides supply air of 25 m/s and 20 m/s at the roof and air curtain gates with a supply temperature of 10 °C, demonstrates optimal thermal performances on both the spectator tiers and the pitch. Compared with the baseline stadium performance, the average reductions in temperature on the pitch and spectator tiers under scenario six could reach 15 °C and 14.6 °C. The reductions in the Predicted Percentage of Dissatisfied values for the upper and lower tiers as well as the pitch were 63%, 74%, and 78%. In terms of the estimated energy consumptions, scenario six would consume electric energy per match at a rate of 25.5 MWh compared with 22.8 MWh for one of the stadiums in the 2010 South Africa World Cup and 42.0 MWh for the 2006 Germany World Cup. Future research is recommended to explore the influence of supply angle on air curtain gates and roof cooling supply slots’ performances.

Protective Environment for Hematopoietic Cell Transplant (HSCT) Recipients: The Infectious Diseases Working Party EBMT Analysis of Global Recommendations on Health-Care Facilities

▪BACKGROUND: An international global perspective for guidelines for health-care facilities in which HSCT recipients are treated was announced in 2009 by Center for International Blood & Marrow Transplant Research, National Marrow Donor Program, European Society for Blood and Marrow Transplantation (EBMT), American Society for Blood and Marrow Transplantation, Canadian Blood and Marrow Transplant Group, Infectious Diseases Society of America, Society for Healthcare Epidemiology of America, Association of Medical Microbiology and Infectious Disease, and Centers for Disease Control. With respect to guidelines on hospital room design and ventilation for HSCT setting, a set of 10 recommendations were presented (Tomblyn et al, 2009).OBJECTIVE: Since the issue is clearly of practical importance to world-wide transplant community, the IDWP-EBMT created a survey in order to present the current status on protective environment for recipients of HSCT, and to analyze the trends and needs in hospital transplant room design and ventilation.METHODS: The questionnaire consisted of 37 questions in all and was divided into 6 sections that included the contact information and details of the protective isolation facility including air filtration, air changes, maintenance, combination of isolation, protective environment room/unit and floor.RESULTS: In all, 177 centres from 36 countries responded to the survey, with average 33% country response rate. Physicians completed 62%, nurses 19% and support staff 19% of the surveys. A total number of 71% of answers were provided to all questions. The total number of unanswered questions was lowest among physicians (23% vs 49%; p<0.001). (A) Among all HSCT centers, in 99.4% patient rooms are equipped with HEPA filters, with central or point-in-use room system in 45.8% and 48%, respectively. The use of HEPA filters with 99.97% efficiency for removing particles ≤0.3µm in diameter, and room ventilation with the rate of at least 12 air changes per hour were confirmed by 70.1% and 71.2% of centers, respectively. Only 29.4% center staff were aware of and could confirm regular replacement of filters based on manufacturers' recommendations, while 53.7% centers have a written procedure for regular filter maintenance and removal and to monitor filtration efficiency in order to best determine appropriate time for replacement, especially in case of ongoing construction. (B) In 59.3% centers, the airflow is directed so that air intake occurs at one side of the room while the air exhaust occurs at the opposite side. Consistent positive air pressure differential between the patient's room and the hallway ≥2.5 Pa (i.e., 0.01 inches by water gauge) was reported by 38.4% centers having a permanently installed device/mechanism to constantly monitor the differential air pressure between the room and the corridor, while the pressure in the anteroom is positive in 19.2% centers, and an air pressure monitoring device/mechanism in the anteroom in addition to the patient room is present in 17.5% of centers. Well-sealed rooms are used in order to prevent infiltration of air from outside the room that could allow entry of spores and hinder maintenance of proper pressure differential, with respect to: windows (in 70.6%), monolithic ceilings (in 35%), and all plumbing pipes in the room (in 51.4% of centers). In order to guarantee the continuous positive pressure, a monitoring system that will set off an alarm when the pressure differential between any protective environment room and adjacent hallway or anteroom falls to less than 2.5 Pa to alert staff to possible engineering failures is installed in 33.9% of centers, and self-closing doors to maintain constant pressure differentials are present in 37.3% of centers. (C) The sensor monitor in the patient room used to determine when the HEPA filters require changing is installed in 18.1% of centers. The nursing staff is able to observe the HSCT recipient by the windows that are installed in the door/wall of the HSCT recipient's room or by the monitoring system in 61.6% of centers.CONCLUSIONS: Knowledge about the maintenance of protective environments in the HSCT setting was inadequate, reflecting a lacking information between health personnel working in the ward and hospital offices. Only 6 centers were able to meet all 10 recommendations listed by Tomblyn et al and few centers were able to meet all the relevant technical requirements. DisclosuresNo relevant conflicts of interest to declare.

Impact of Air Infiltration on IAQ and Ventilation Efficiency in Higher Educational Classrooms in Spain

Indoor air quality (IAQ) in educational buildings is a key element of the students’ well-being and academic performance. Window-opening behavior and air infiltration, generally used as the sole ventilation sources in existing educational buildings, often lead to unhealthy levels of indoor pollutants and energy waste. This paper evaluates the conditions of natural ventilation in classrooms in order to study how climate conditions affect energy waste. For that purpose, the impact of the air infiltration both on the IAQ and on the efficiency of the ventilation was evaluated in two university classrooms with natural ventilation in the Continental area of Spain. The research methodology was based on site sensors to analyze IAQ parameters such as CO2, Total Volatile Organic Compounds (TVOC), Particulate Matter (PM), and other climate parameters for a week during the cold season. Airtightness was then assessed within the classrooms and the close built environment by means of pressurization tests, and infiltration rates were estimated. The obtained results were used to set up a Computational Fluid Dynamics (CFD) model to evaluate the age of the local air and the ventilation efficiency value. The results revealed that ventilation cannot rely only on air infiltration, and, therefore, specific controlled ventilation strategies should be implemented to improve IAQ and to avoid excessive energy loss.