Characterization of minienvironments in a clean room: Design characteristics and environmental performance

A minienvironment is normally used to maintain a level of stringent cleanliness through controlling particle concentrations within a tightened volume of clean spaces. Because minienvironments are expected to locally achieve a higher level of cleanliness than their adjacent clean room, it is important to understand the characteristics of their design and operation and effectiveness in environmental control. This paper presents findings from an in-situ study on a group of minienvironments, with the focus on characterizing and evaluating environmental performance of the minienvironments as part of a large-scale of in-situ investigation into the total performance of the minienvironments operating in a clean room. In particular, this paper summarizes design and operating characteristics and presents measured environmental performance of five minienvironments and the clean room that housed them. The study discovers that pressure differentials as low as under 0.2 Pa can be sufficient for achieving a high level of air cleanliness to meet environmental control expectation and requirements. Comparisons with relevant industry standards show that existing standards or guidelines may have been suggesting thresholds that are higher than necessary at least in some minienvironment applications. The paper suggests potential benefits from identifying and optimizing the required range of pressure differentials, and likely opportunities and challenges in improving the system's total performance through further studies and refining relevant standards.     

Performance of large fan-filter units for cleanroom applications

Fan-filter units (FFUs) are widely used in clean space to re-circulate and remove particles out of the airflows directed to cleanrooms or minienvironments. Energy and aerodynamic performance of FFUs may largely influence both energy efficiency and effectiveness in contamination control in the cleanroom design, qualifications, and operation. This article presents laboratory-measured performance of seven relatively new and large FFUs, with a section size of 122-cm×122-cm, or 4-ft×4-ft. In addition, this article includes a comparison of the performance of these large FFUs with that of smaller, 122-cm×61-cm (or 4-ft×2-ft) FFUs that were previously tested. The comparison was based upon a set of performance metrics such as total pressure efficiency (TPE) and energy performance index (EPI). This article found that there were wide variations in the energy performance of FFUs, and that using a consistent evaluation method can generate comparable FFU performance information. When operating at the maximal setting of speed control dials used to control their respective fan-wheel speeds, the larger units in this study tended to be more energy efficient than their smaller counterparts. The energy efficiency level of the same unit may vary considerably, depending on actual operating conditions such as airflow speeds and pressure rise across the units. Furthermore, this article provides recommendations for further investigations to improve energy efficiency of FFU applications.     

Study on contamination control in a minienvironment inside clean room for yield enhancement based on particle concentration measurement and airflow CFD simulation

A study was carried out to look for the source of contamination and examine the route of contaminant transfer in the minienvironment applied in LCD process clean room of Korea. As the minienvironment model, one of the clean room with much large space and low particle concentration was selected to investigate. Firstly, the particle concentrations were measured without any information on the source and the route of contaminants transfer. Through considering the results of particle measurements and CFD simulations simultaneously, however, it was revealed that the critical contamination source was the stocker and the contaminants were transferred by the airflow pattern in this study. As an improvement action, reducing the airflow rate of exhaust fans and installing additional fan filter units (FFUs) were carried out. As a result, the velocity distribution was improved and the particle concentration was reduced in the target minievironment. Also, the defect rate related to this minienvironment decreased. With the help of the experimental and the numerical tools, the effective method for contamination control was developed. Furthermore, this article provides recommendation for future work to improve the yield and save the energy consumption simultaneously.     

Assessing energy performance in the latest versions of Hong Kong Building Environmental Assessment Method (HK-BEAM)

The latest (4/04 and 5/04) versions of the Hong Kong Building Environmental Assessment Method (HK-BEAM), one covering new buildings and the other existing buildings, have been formally launched in 2005. The paper describes the building energy performance assessment method in these latest HK-BEAM versions. With the use of the energy budget approach, the assessment framework is applicable to a wide range of buildings that may comprise different mixes of premises types. The new scheme provides bonus credits for provisions that allow utilization of renewable energy sources. For existing buildings, it makes allowances for plant performance degradation and constraints to implementation of improvement measures in existing buildings. So far, the new assessment method has been applied to six building developments, including commercial complexes and residential developments. The assessment results are presented and discussed in the paper.     

Efficiency of energy recovery ventilator with various weathers and its energy saving performance in a residential apartment

The energy recovery ventilator (ERV) is an effective method, which can transfer heat and moisture from the exhaust air into the outdoor fresh air to save energy in buildings. Nowadays, ERV has been widely used in the commercial, industrial and residential buildings in China. Its energy saving performance depends on a lot of factors, such as the outdoor environmental conditions, the enthalpy efficiency of the exchanger, and so on. Based on the relationship among sensible heat, latent heat and enthalpy efficiency, we analyzed the weighted coefficient equations for describing the performance of ERV in different climatic zones in China. According to China weather data, enthalpy efficiency of the exchanger mainly depends on sensible heat efficiency in winter and latent heat efficiency in summer. The energy simulations of a sample apartment in a residential building were made under different operation conditions to study the performance of ERV. The energy saving performances of the ERV were studied with five different outdoor climatic conditions, the enthalpy efficiency, fan power consumption of ERV and fresh air change rate. To improve energy saving performance, better efficient enthalpy exchange material and higher effiencient fans must be explored, while reasonable fresh air change rate as well as proper operation period according to local climate should also be carefully considered.     

Climatic zoning and its application to Spanish building energy performance regulations

The main requirements of European Directive 2002/91/EC on the energy performance of buildings (EPBD) are the application of minimum energy performance requirements for new buildings and certification of the energy performance of buildings. Its transposition into the national law of member states of the European Union has signified the appearance of new and more onerous requirements in terms of construction quality from the point of view of energy performance, and in terms of the procedure for certification of the energy performance of buildings. In both cases, the levels required tend to be based on climatic conditions, fundamentally in countries such as Spain, where the climatic variability is very pronounced. This paper presents a methodology developed for the climatic zoning of the localities not included in the above-mentioned regulations in order to facilitate their application. By way of example, the method is shown which was used to generate the climatic files and carry out the subsequent climatic zoning of all the municipalities of the region of Andalusia in southern Spain.     

Investigation of energy performance of newly built low-energy buildings in Sweden

Energy use in the built environment represents a large part of total energy use in Sweden and is one important sector where energy conservation needs to be significantly improved in order to meet the national implementation of the European goals. One key question that needs to be investigated in relation to these goals is the performance and implementation of passive or low-energy houses. This paper presents results and an evaluation of a newly built house in an area with passive houses in Linköping, Sweden. Nine passive houses were built with the aim to be energy efficient, with an annual space heating demand of 21 kWh/m², and at the same time to have the same visual appearance as any other building in the surrounding area.This study evaluates the energy performance of a residential area with low-energy buildings based on Building Energy Simulation (BES) (IDA ICE 4), and measurements from the real object. Both annual and hourly validation is performed using room by room modeling and internal heat gains. A novel approach to internal heat gain modeling is presented using time-use data (TUD). The results show possible improvements in the design, the building envelope and in the heating control.     

Assessing the performance of sustainable technologies: a framework and its application

A recently developed framework to provide a logical structure for the a priori assessment of a particular technology with regard to sustainability concepts, performance, and relevancy to a project's construction process and operation is introduced. The framework is designed to assist project stakeholders and policy-makers in systematically identifying and evaluating the implications and relative merits of a range of alternative sustainable technologies. Building professionals were consulted throughout the development of the framework: to test the completeness of the framework; to capture the value systems of various industry participants in order to reflect them in the framework; and to gather information on the advantages and disadvantages of the green roof technology. The framework is applied to the example of the green roof technology, and the order-of-magnitude estimates are developed for performance measures identified as important from the perspective of industry professionals. The technology is evaluated for different configurations of the same building type to demonstrate the effect of building context on performance. The framework can be used to assist in the assessment of the positive and negative implications of a particular technology with respect to value systems and context, and, therefore, may be used to explain market behaviour, assist policy-makers in developing meaningful regulations and incentives, and provide feedback regarding a new technology in an objective manner.

L'auteur présente un cadre qui a été récemment développé pour offrir une structure logique destinée à l'évaluation a priori d'une technologie particulière en ce qui concerne les concepts de durabilité, les performances et la pertinence eu égard au processus de construction et à l'exploitation d'un projet. Ce cadre est conçu pour aider les acteurs d'un projet et les décideurs à identifier et évaluer de manière systématique les implications et les avantages relatifs d'une panoplie de technologies durables alternatives. Durant toute la période de développement du cadre, on a consulté des professionnels de la construction; l'objectif était de tester l'aspect complet du cadre, de capturer les systèmes de valeur des divers participants industriels pour qu'ils soient présents dans le cadre et de collecter des informations sur les avantages et les inconvénients de la technologie des terrasses végétalisées. Ce cadre s'applique à la technologie des terrasses végétalisées et les estimations de l'ordre de grandeur sont calculées pour des mesures de performances importantes aux yeux des professionnels de cette industrie. Cette technologie est évaluée pour différentes configurations d'un même type de bâtiment afin de démontrer les effets du contexte du bâtiment sur les performances. Le cadre peut servir à aider à évaluer les implications positives et négatives d'une technologie donnée par rapport aux systèmes de valeur et au contexte et peut donc être utilisé pour expliquer le comportement du marché, pour aider les décideurs à formuler des règlementations et des incitations significatives et pour fournir de manière objective un retour d'information sur une nouvelles technologie.

Mots clés: terrasses végétalisées, mesures de performances, gestion des risques, implication des intervenants, développement durable, technologie durable évaluation de la technologie     

Evaluation of energy performance indicators and financial aspects of energy saving techniques in residential real estate

The energy consumption in the existing residential building stock accounts for about 40% of the total energy consumption in the built environment. Different types of energy performance indicators to assess the energy consumption of buildings were and still are internationally under development. In this paper we compare the methodologies and accuracies of three Dutch energy performance indicators by applying them to eight houses. This application shows that the actual domestic energy use is linearly correlated with the estimated energy consumption given by the energy performance indicators, but 7-25% lower.Based on the energy performance indicators and actual energy use, we offer a methodology to incorporate additional revenues within the financial analysis of energy saving techniques. These revenues are related to the value of the dwelling in which the techniques are installed. We use the same houses to analyse the financial returns on energy saving investments. By assigning the value increase of real estate to two popular specific energy saving techniques, namely wall and roof insulation, it is found that the payback period could be 40-50% shorter than when it is solely based on investment costs and energy prices.     

Investigation of air management and energy performance in a data center in Finland: Case study

This is the first research paper on data center from Finland. The objectives of this study are to evaluate air management and energy performance of cooling system and investigate the possibilities of energy saving and reuse in the data center. Field measurements, particularly for long term's IT and facility powers, were conducted. Different performance metrics for the cooling system and power consumption were examined and analysed. Key problem areas and energy saving opportunities were identified. The electrical end use breakdown was estimated. Results show that IT equipment intake conditions were within the recommended or allowable ranges from ASHRAE. The Power Usage Effectiveness (PUE) value for a typical year was about 1.33. Noticeable recirculation of hot air was not observed, but extreme bypass air was found. The air change rate was set much bigger than the recommended ASHRAE's value. There was no heat recovery system. The air management and heat recovery issues therefore need to be addressed. Fan speeds (Computer Room Air-Conditioning Unit) should be reduced and the ventilation rate should be minimized. Further, a simulated heat recovery system was presented demonstrating that the data center could potentially provide yearly space and hot water heating for 30,916 m² non-domestic building.     

A systematic methodology for optimising the energy performance of buildings in Bahrain

Today, a great deal of effort is ongoing all over the world to find methods for optimising the energy performance of buildings. Such efforts can be seen in the European Energy Performance of Building Directive (EPBD). This directive aims to ensure energy saving and CO₂ emission reduction without compromising the local conditions and people's comfort. In the Gulf States, however, there is a need for such methods due to their economic and environmental benefits. This study introduces a simple but reliable methodology for optimising building energy performance in Bahrain. The methodology is based on building management systems (monitoring, analysing and targeting future performance), simulation tools and other technologies. This methodology was implemented using Visual DOE and was directly related to collectively gathered data gained form experimental works and practical applications. By means of the introduced methodology, energy consumption was obtained together with energy cost and CO₂ emissions. The applicability of this methodology was demonstrated through optimising a case office building in Bahrain.     

Development of energy performance benchmarks and building energy ratings for non-domestic buildings: An example for Irish primary schools

The EU Member States are in the process of implementing energy rating procedures for buildings. For non-domestic buildings in particular, devising a robust and cost effective energy rating method is not a simple task. The situation becomes more complicated where countries do not have a tradition of performing energy calculations or undertaking energy measurements in buildings.     

Eawag Forum Chriesbach—Simulation and measurement of energy performance and comfort in a sustainable office building

The Eawag's new headquarters “Forum Chriesbach” is an exemplary illustration of a ‘sustainable’ construction design for office buildings. With a unique combination of architectural and technical elements the building reaches a very low 88 kWh/m² overall primary energy consumption, which is significantly lower than the Swiss Passive House standard, Minergie-P. A monitoring and evaluation project shows that the building is heated mainly by using the sun and internal heat gains from lighting, electrical appliances and occupants, resulting in an extremely low space heating demand. Cooling is provided by natural night time ventilation and the earth-coupled air intake, which pre-cools supply air and provides free cooling for computer servers. However, values for embodied energy and electricity consumption remain significant, even with partial on-site electricity production using photovoltaics. TRNSYS computer simulations show the contributions of individual building services to the overall energy balance and indicate that the building is resilient towards changes in parameters such as climate or occupancy density. Measurements confirm comfortable room temperatures below 26 °C, even during an extremely hot summer period, and 20-23 °C in the winter season. An economic analysis reveals additional costs of only 5% compared to a conventionally constructed building and a payback-time of 13 years.     

Comparison between measured and calculated energy performance for dwellings in a summer dominant environment

The objective of this study is to present a comparison between the measured and the calculated energy performance of dwellings. For this purpose, the energy consumption of ten dwellings is measured for one year. The added value of this work is that it is performed in a summer dominant environment. The energy needs of the same dwellings are also calculated by means of the methodology based on European Standards described in the CEN/TR 15615:2008 technical report. According to the findings of this study, a large gap exists between the calculated and the measured energy consumption of the examined dwellings. In order to evaluate the reasons for this deviation, a detailed analysis of the heating and cooling loads of the dwellings is performed. The intermittent heating of the building is found to be simulated accurately by the employed methodology, whereas the comparison between the calculated and the measured cooling loads reveals a large deviation of about 150%. Based on the findings of this study, a factor of 0.6 should be adopted in the case of cooling schedule, compared to the heating operation of the building.     

A study of energy performance and efficiency improvement procedures of Government Offices in Hong Kong Special Administrative Region

A study of energy performance in 19 Government Offices in Hong Kong has been carried out. The characteristics of Government Offices, difficulties and results in assessing their building energy performance are discussed and reported. An average Energy Use Index based on unit floor area has been derived for the Government Offices using energy consumption data in the past three years. A number of factors that are likely affect the energy use in buildings, such as year of construction and total gross floor area are reviewed. Energy management opportunities are identified and proposed after carrying out energy audit to the Government Offices. Operational practices to improve energy performance are also recommended.     

Control tuning of a simplified VAV system: Methodology and impact on energy consumption and IAQ

Nowadays, with the improvement of living standards, air-conditioning systems have been widely used causing more health problems linked to air-conditioning systems and indoor air quality. When an air handling unit is designed for a conference room, its variable use demands an outdoor air rate control in particular to optimize energy consumption of the new air heating/cooling. Based on an experimental site, the present work shows how to combine air quality and the improvement of energy consumption thanks to a way to define a control strategy. The control problem considered here is the management of air quality associated to a control of the outdoor air rates. A review of classical tuning methods is led in order to select suitable ones. Thus, a linearization of the phenomena must be done to border the system expression in tuning methods. Several classical methods are studied and the family model is chosen: monovariable and multivariable applications are brought to fruition. Simulations and applications permit to enhance energy consumption through the choice of a strict way to tune such control equipments.