Impact on power quality due to large-scale adoption of compact fluorescent lamps – a review

The demand of electrical energy has grown tremendously in the last couple of decades across the globe. The energy conservation and management has attracted the attention of stake holders for efficient utilisation of the resources. One of the major steps taken by the authorities towards conservation of electrical energy is replacement of incandescent lamps (ILs) by compact fluorescent lamps (CFLs). CFL uses electronic circuit for its ignition, making them a non-linear load on utility grid. Large-scale replacement of ILs has enormous effects on utility grid in terms of power quality. This paper reviews the work conducted by several researchers investigating the effect of using CFLs on power quality. Basic terminologies related to power quality is defined. The experimental results elaborate the pollution on the grid in the term of total harmonic distortion in current due to adoption of CFLs. The methodologies of harmonic measurement system are reviewed. Different software used for the analysis is presented. The paper will help the researchers to receive a comprehensive overview of power-quality issues.     

Investigation into ultraviolet radiations from modern electric light sources

Due to concerns of increasing electrical energy demand and government regulations, traditional incandescent lamps are being replaced by energy-efficient lamps, such as compact fluorescent lamps (CFLs) and light emitting diodes (LEDs). The widespread adoption of new solid-state light sources requires investigation into several effects associated with these alternative light sources. One of the important concerns is ultraviolet (UV) radiations coming out of these new light sources. This brief report presents the experimental data obtained on UV radiations from CFLs and LEDs.     

An evaluation of residential CFL hours-of-use methodologies and estimates: Recommendations for evaluators and program managers

This paper presents a review of methodologies and results of evaluations examining hours-of-use in compact fluorescent lamps (CFLs). Hours-of-use is a crucial variable in determining the cost-effectiveness of lighting programs, and there is extensive variation in hours-of-use estimates across methodologies and within a particular methodology. Given the different sources of variation, one must be careful in comparing the results from different studies. However, we are able to recommend a robust methodology that should be used by evaluators of lighting programs, regardless of geography or program delivery type.     

Microbial contamination of indoor air due to leakages from crawl space: a field study

Mechanical exhaust ventilation system is typical in apartment buildings in Finland. In most buildings the base floor between the first floor apartments and crawl space is not air tight. As the apartments have lower pressure than the crawl space due to ventilation, contaminated air may flow from the crawl space to the apartments. The object of this study was to find out whether a potential air flow from crawl space has an influence on the indoor air quality. The results show that in most cases the concentration of fungal spores was clearly higher in the crawl space than inside the building. The size distribution of fungal spores depended on the fungal species. Correlation between the fungal spores in the crawl space and indoors varied with microbial species. Some species have sources inside the building, which confounds the possible relation between crawl pace and indoor concentrations. Some species, such as Acremonium, do not normally have a source indoors, but its concentration in the crawl space was elevated; our measurements showed also elevated concentrations of Acremonium in the air of the apartments. This consistent finding shows a clear linkage between fungal spores in the indoor air and crawl space. We conclude that a building with a crawl space and pressure difference over the base floor could be a potential risk for indoor air quality in the first floor apartments.     

Mercury vapor in residential building common areas in communities where mercury is used for cultural purposes versus a reference community

BACKGROUND: Exposure to elemental mercury (Hg0) in residential buildings can occur from accidental spills, broken objects (thermometers, fluorescent fixtures, thermostats), and deliberate introduction, one mode of which involves cultural practices by individuals who believe dispersal of mercury in a residence will bring luck, enhance health or ward off harm. OBJECTIVES: To determine whether mercury vapor levels in common areas of residential buildings is higher in a community where cultural uses are likely (study areas S1, S2) than in a reference community (C1) where cultural use is unlikely, and whether levels can serve as a signal of significant cultural mercury use. METHODS: We monitored Hg0 vapor with a portable spectrophotometer in the three communities. We randomly selected sites in S1 and C1 community, and also include sites in S2 specified by local health officials who suspected cultural mercury use. We evaluated 122 multifamily buildings and 116 outdoor locations. FINDINGS: We found >25 ng/m3 Hg0 in 14% of buildings in study areas compared to only one reference building. In the latter we identified an accidental mercury spill from a bottle that had been brought into the building. Both the mean and maximum indoor mercury vapor levels were greater in the study communities than in the reference community. In all communities, we observed mean indoor Hg0 vapor concentration greater than outdoors, although in two-thirds of buildings, indoor levels did not exceed the area-specific outdoor upper-limit concentration. CONCLUSION: After controlling for factors that might influence Hg0 vapor levels, the most plausible explanation for greater Hg0 levels in the study area is a relationship to cultural use of mercury. None of the measured levels exceeded the ATSDR minimum risk level for residences of 200 ng/m3 Hg0 although levels in living quarters might be greater than those in the common areas.     

Performance of three air distribution systems in VOC removal from an area source

Building-related health complaints and symptoms represent a significant occupational health problem. Elevated concentrations of various types of indoor pollutants, frequently associated with inadequate ventilation, have been implicated as a potential cause. The objective of this research is to model and evaluate the performance of several ventilation methods in pollutant removal from indoor environments. Pollutant sources are assumed to be at the floor level, one with a constant emission rate and the other a fast decaying source (volatile organic compound emissions from a wood stain). Three ventilation methods, namely displacement ventilation and two mixing systems using a side grille and ceiling square diffuser respectively are studied. A computer model has been applied to simulate the distributions and the time history of the pollutant concentrations in a mockup office. Experimental data of velocity, temperature, and tracer gas concentration distributions in the chamber with the displacement diffuser are obtained to validate the airflow model. Simulation results show that different ventilation methods affect the pollutant distributions within the room. When the pollutant sources are distributed on the floor and not associated with a heat source or initial momentum, displacement ventilation behaves no worse than perfect mixing ventilation at the breathing zone. Conventional “mixing” diffusers, on the other hand, could perform better or worse than a perfect mixing system. The computer model could be used for selecting appropriate ventilation systems to maximize indoor air quality for occupants.     

Fine particle number and mass concentration measurements in urban Indian households

Fine particle number concentration (D(p)>10 nm, cm(-3)), mass concentrations (approximation of PM(2.5), microg m(-3)) and indoor/outdoor number concentration ratio (I/O) measurements have been conducted for the first time in 11 urban households in India, 2002. The results indicate remarkable high indoor number and mass concentrations and I/O number concentration ratios caused by cooking. Besides cooking stoves that used liquefied petroleum gas (LPG) or kerosene as the main fuel, high indoor concentrations can be explained by poor ventilation systems. Particle number concentrations of more than 300,000 cm(-3) and mass concentrations of more than 1000 microg m(-3) were detected in some cases. When the number and mass concentrations during cooking times were statistically compared, a correlation coefficient r>0.50 was observed in 63% of the households. Some households used other fuels like wood and dung cakes along with the main fuel, but also other living activities influenced the concentrations. In some areas, outdoor combustion processes had a negative impact on indoor air quality. The maximum concentrations observed in most cases were due to indoor combustion sources. Reduction of exposure risk and health effects caused by poor indoor air in urban Indian households is possible by improving indoor ventilation and reducing penetration of outdoor particles.     

Financial and energy impacts of compact fluorescent light bulbs in a rural setting

Within the context of a national campaign to replace GLS with CFLs, a pilot study was undertaken in Niha, Lebanon to replace around 1000 light bulbs. This paper reports on the detailed savings actually obtained by this project. Energy savings were found to be 8.3%. The obtained savings were lower than the theoretical savings expected mainly due to apparent lower time of use than expected prompting a more moderate advertised yearly savings. The beneficiaries’ attitude towards CFLs was assessed and the results indicate a general satisfaction and willingness to purchase CFLs. One major drawback has been the dissatisfaction with light intensity. The impact of the campaign on other village residents was assessed and the campaign was successful in convincing one third of the population to install CFLs and two thirds said that they intend to buy CFLs in the future. A new approach in the campaign for CFL promotion is suggested.     

Annual characteristics of ventilation and indoor air quality in detached houses using a simulation method with Japanese daily schedule model

This paper presents the results of investigations that were made on a simulation program, which calculates the temperature, the heat loads, the ventilation rates and the indoor air quality considering the Japanese daily schedule and the dweller's behaviour toward keeping comfortable indoor climate, in order to explain the effect of ventilation systems. In the investigation, the concentrations of carbon dioxide, carbon monoxide and formaldehyde are regarded as indicators of indoor air quality. Firstly, three types of systems were designed in a house model; that is a basic passive ventilation system, a passive stack ventilation system and a mechanical ventilation system. Next, the simulation was performed using the standard weather data on three cities in Japan; and the simulation made clear the annual characteristics of ventilation and indoor air quality. The results show that in a house with a passive ventilation system, there is much risk of indoor air pollution in spring, autumn and when air conditioned, and that indoor air quality in the rooms on the first floor differs from that on the second floor. Lastly, the performance of the ventilation systems and the solution methods of realizing these ventilation systems were discussed on the basis of the results of the simulation.     

Optimization of cooling load for a lecture theatre in a composite climate in India

A lecture theatre with dimension 16 m × 8.4 m × 3.6 m located at Roorkee (28.58°N, 77.20°E) in the northern region of India, is selected to calculate the monthly and annual cooling load (kWh) and cooling capacity of air conditioning system by a computer simulation. The paper also presents the results of a study investigating the effect of different glazing systems on windows and the reduction in building cooling load. DesignBuilder software has been used for the computer simulation for calculating the cooling load. The paper aims to investigate the reduction in thermal gains and cooling load requirements by varying the U-values of different glazing types, insulating the ceiling, providing cool roofs, interior and exterior insulation on walls, and replacing the conventional fluorescent tube lamp (FTL) by energy efficient compact fluorescent lamp (CFL). Installation of false ceiling, wall insulation, different glazing types and lighting systems are cost effective with normalized annual saving ranging from 17% to 19.8% from this retrofitting project. Furthermore, the study also highlights the potential of reducing the emission of CO₂ and equivalent carbon credit. Retrofitting techniques strongly influence the level of energy saving, although the payback period is generally quite long of order 8 years.     

Estimating the effects of ambient conditions on the performance of UVGI air cleaners

Ultraviolet germicidal irradiation (UVGI) uses UVC radiation produced by low pressure mercury vapor lamps to control biological air contaminants. Ambient air velocity and temperature have a strong effect on lamp output by influencing the lamp surface cold spot temperature. In-duct UVGI systems are particularly susceptible to ambient effects due to the range of velocity and temperature conditions they may experience. An analytical model of the effect of ambient conditions on lamp surface temperature was developed for three common lamp types in cross flow from a convective–radiative energy balance assuming constant surface temperature. For one lamp type, a single tube standard output lamp, UVC output and cold spot temperature data were obtained under typical in-duct operating conditions. Over an ambient temperature range of 10–32.2 °C and an air velocity range of 0–3.25 m/s, measured cold spot temperature varied from 12.7 to 41.9 °C and measured lamp output varied by 68% of maximum. Surface temperatures predicted by the heat transfer model were 6–17 °C higher than corresponding measured cold spot temperatures, but were found to correlate well with cold spot temperature via a two-variable linear regression. When corrected using this relationship, the simple model predicted the cold spot temperature within 1 °C and lamp UVC output within ±5%. To illustrate its practical use, the calibrated lamp model was employed in a simulation of the control of a contaminant in a single-zone ventilation system by an in-duct UVGI device. In this example, failure to account for the impact of ambient condition effects resulted in under-prediction of average space concentration by approximately 20% relative to a constant output system operating at maximum UVC output.     

上海大学生宿舍夏季室内热环境实测和调查

本文采用实测和调查的方法对松江大学城二期的寝室楼典型房间夏季室内气温进行了实测,并发放了热感觉调查问卷。对实测数据和调查结果的分析表明:在亚热带季风型气候的上海,寝室的朝向对于温度有着较大的影响,同时,楼层的高度和室内的通风情况都对楼内温度起到一定的影响,随着楼层的上升,整体温度降低同时通风更加顺畅。在另一方面,问卷的统计结果显示寝室内部整体的舒适性很难达到令人满意的程度,温度和湿度均在相当程度上令人感到不适。     

Measurements of mercury in the near-surface layer of the atmosphere of the Russian Arctic

A series of measurements of gaseous elemental mercury concentrations in near-surface air of the Russian Arctic Region were carried out from 1994 to 1997. The measurements were conducted in Murmansk at a stationary site in April-May 1994, on a cruise in Motovsky Bay and Kola Bay during May-June 1996, and along the Russian Northern Sea Route in April-May 1997 on board the nuclear icebreaker 'Soviet Union'. Silver absorption was used for trapping of mercury and the mass of mercury was determined by cold vapour atomic absorption spectrophotometery. Detection limits were approximately 0.3 ng/m(3) (+/- error 46%). Sixty samples were selected and analysed. Sample volumes were 2.2 m(3) ashore, and up to 6.6 m(3) over water. The meteorological conditions, including a wind speed and direction, during the sampling period were typical of the spring-summer period of year, and therefore the concentrations of atmospheric mercury are regarded as representative for this season. The mean concentrations of mercury ranged from 2.2 ng/m(3) for Murmansk city, 1.7 ng/m(3) for Kola Bay, 1.6 ng/m(3) for Motovsky Bay, 1.1 ng/m(3) for the eastern part of the Barents Sea and 0.7 ng/m(3) for the western part of the Kara Sea. The levels of mercury in Murmansk, and over Kola and Motovsky Bays were associated with a primary direction of a near-surface wind from the nearest sources of mercury emission located in the Russian North region. These are the non-ferrous metallurgical plants in Nickel in the case of Motovsky Bay and Murmansk garbage-disposal plant, for sampling points in Murmansk and over Kola Bay. These concentrations of mercury, measured in the spring-summer season, in near-surface air of the Russian North, are more than two-fold lower than the concentrations that are typical of continental background regions in western Russia, and are comparable to the concentrations measured in the Arctic regions of other countries.     

地板辐射与置换通风空调系统运行参数

建立了基于EnergyPlus的地板辐射供冷加置换通风空调系统模型,模拟得到的室内温度和辐射地板所承担冷量与实验结果的误差小于±7%。在此模型基础上,改变送风参数和供水参数,得到置换通风供冷量、辐射地板供冷量、地板表面温度、室内空气平均温度、AUST温度等参数的变化规律。结合热舒适性模型,得到满足室内热舒适性(-0.5≤PMV≤0.5)条件下,置换通风的送风参数和辐射地板的供水参数范围,为复合系统设计和应用提供依据。     

下送上回通风方式供冷与供暖运行性能比较

下送上回通风方式目前得到了广泛的研究应用,其供冷运行时就是置换通风,但同样一套通风系统在一些地区的寒冷季节则有可能需要作供暖运行.为了获得下送上回通风系统在分别作供冷与供暖运行时的具体性能参数,本文应用实验测试与计算流体力学(CFD)模拟的方法研究了置于环境实验室内的某办公环境.研究中分析比较了该办公环境内的空气速度、温度以及追踪气体污染物的浓度分布.研究结果表明,下送上回通风方式作供冷运行时空气温度及污染物浓度分层现象明显,空气处于半混合状态,置换效果较好;作供暖运行时,温度及污染物浓度趋于均匀,通风系统性能接近于混合送风系统,不具备良好的抑制交叉污染的能力.     

Indoor air quality in the university libraries of Modena (Italy)

We carried out a survey in 16 libraries of the University of Modena, Northern Italy, to assess the indoor exposure to volatile organic compounds (VOCs), including formaldehyde, and total dusts. Data were collected on the main structural characteristics of the buildings; indoor microclimate parameters, such as temperature, relative humidity and ventilation rate were measured and air samples taken inside and outside the libraries. The mean value of total dusts was 190 +/- 130 microg/m3 with a wide range of values. Formaldehyde was found in only ten out of 16 libraries and the indoor concentrations ranged from 1.70 to 67.8 microg/m3 with an average value of 32.7 +/- 23.9 microg/m3. On the whole, VOCs were present in all the libraries investigated with an average value was 433 +/- 267 microg/m3 (range 102-936 microg/m3). No correlation was found among VOCs, formaldehyde and total dusts nor was a significant association observed with microclimatic parameters or the structural characteristics of the buildings. The general situation found in this study suggests no major problems related to indoor pollution. However, some of the pollutants investigated such as total dust and total VOCs deserve further investigation. It is important to identify the possible sources of contaminants and to define the relationship between indoor and outdoor levels of pollutants more accurately, taking into account the effects of air recycling due to natural ventilation systems.     

Modeling ventilation and radon in new Dutch dwellings

Indoor radon concentrations were estimated for various ventilation conditions, the differences being mainly related to the airtightness of the dwelling and the ventilation behavior of its occupants. The estimations were aimed at describing the variation in air change rates and radon concentrations to be expected in the representative newly built Dutch dwellings and identifying the most important parameters determining air change rate and indoor radon concentration. The model estimations were compared with measurements. Most of the air was predicted to enter the model dwelling through leaks in the building shell, independent of the ventilation conditions of the dwelling. Opening the air inlets was shown to be an efficient way to increase infiltration and thus to decrease radon concentration. The effect of increasing the mechanical ventilation rate was considerably less than opening the air inlets. The mechanical ventilation sets the lower limit to the air change rate of the dwelling, and is effective in reducing the radon concentration when natural infiltration is low. Opening inside doors proved to be effective in preventing peak concentrations in poorly ventilated rooms. As the airtightness of newly built dwellings is still being improved, higher radon concentrations are to be expected in the near future and the effect of occupant behavior on indoor radon concentrations is likely to increase. According to the model estimations soil-borne radon played a moderate role, which is in line with measurements.     

A note on elevated total gaseous mercury concentrations downwind from an agriculture field during tilling

Elevated mercury concentrations were measured at the University of Connecticut's mercury forest flux tower during spring agricultural field operations on an adjacent corn field. Concentrations at the tower were elevated, a peak of 7.03 ng m(-3) over the background concentration of 1.74+/-0.26 ng m(-3), during times when the prevailing wind was from the direction of the corn field and during periods when the soil was disturbed by tilling. Strong deposition to the forest was recorded at the point of measurement when atmospheric mercury concentrations were elevated. The strongest deposition rate was a 1 hour maximum of -4011 ng m(-2) h(-1) following the initial peak in atmospheric concentrations, Analyses of the meteorological conditions and mercury content in agricultural soil, manure and the diesel consumed in the tilling operation indicate that the source of the mercury was from the agricultural tilling operations and it was advected over the tower enriching the atmospheric concentrations above the forest canopy leading to deposition. These results indicate that agriculture operations resulting in a disturbed soil surface may be a source of atmospheric mercury originating from the pool of mercury bound in the soil. This represents a previously undocumented source of mercury emissions resulting from anthropogenic activities.     

Exhaust ventilation in attached garages improves residential indoor air quality

Previous research has shown that indoor benzene levels in homes with attached garages are higher than homes without attached garages. Exhaust ventilation in attached garages is one possible intervention to reduce these concentrations. To evaluate the effectiveness of this intervention, a randomized crossover study was conducted in 33 Ottawa homes in winter 2014. VOCs including benzene, toluene, ethylbenzene, and xylenes, nitrogen dioxide, carbon monoxide, and air exchange rates were measured over four 48‐hour periods when a garage exhaust fan was turned on or off. A blower door test conducted in each garage was used to determine the required exhaust fan flow rate to provide a depressurization of 5 Pa in each garage relative to the home. When corrected for ambient concentrations, the fan decreased geometric mean indoor benzene concentrations from 1.04 to 0.40 μg/m³, or by 62% (P<.05). The garage exhaust fan also significantly reduced outdoor‐corrected geometric mean indoor concentrations of other pollutants, including toluene (53%), ethylbenzene (47%), m,p‐xylene (45%), o‐xylene (43%), and carbon monoxide (23%) (P<.05) while having no impact on the home air exchange rate. This study provides evidence that mechanical exhaust ventilation in attached garages can reduce indoor concentrations of pollutants originating from within attached garages.     

地板辐射与置换通风组合空调系统的模拟

探讨了地板辐射供暖、供冷系统与置换通风系统的组合空调系统的流程,对组合空调系统进行了数值模拟。地板辐射供暖、供冷系统与置换通风系统相结合获得了良好的室内温度场和速度场,提高了空气品质,改善了室内的热舒适性。