Master of Science in Building Services Engineering
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- item: Thesis-Full-textFeasibility study on tubular skylights to be used in Sri Lankan office buildingsKumara, BYBCP; Rodrigo, ATubular Daylight Guidance technology can deliver natural light in to a space in a building where daylight is limited with an internally mirrored pipe system using the phenomena called total internal reflection. This research has been conducted to identify the potential and feasibility of applying Tubular skylights in a Sri Lankan office building. The research has focused on the existing technologies and evaluated three models of Tubular skylights designed to be used in office applications. Computer simulations have been carried out to evaluate the light out puts of different lighting arrangements made with Tubular skylights. Energy evaluations have been carried out for the cases require artificial lighting to keep constant illuminance levels. Economic evaluations have been carried out with life cycle cost calculations to evaluate the economic feasibility.
- item: Thesis-Full-textStrategic guidelines for selection of best energy efficient air conditioning system/equipment for commercial buildings in Sri Lanka(2015-10-15) Perera, KAK; Attalage, RAAir conditioning was considered a luxury in earlier days and now it becomes a general requirement due to urbanization, new constructions, modern architecture, regulations and standards etc. In early days there were no limitations on space and also there were lot of greenery which supports concepts such as natural ventilation. Therefore importance of establishing proper procedure for AC system development is great and this study aims at developing a systematic procedure for selection of efficient AC system/equipment for different type of commercial buildings. Literature review discuss broadly on technologies, standards and regulations, energy efficiency, Calculation techniques and tools, Building envelope improvements which is the flat form for development of a methodology to achieve research objective. Methodology developed consist of three phases namely Design, Testing and Commissioning, Operation and Maintenance. In Sri Lanka focus is mainly given for design phase and neglect T & C, O & M phases which is so critical for success of the project. Once methodology established guidelines have been developed for easy reference so that even layman can understand approach required for development of efficient AC system for his new building. Real time case study presented for better understanding of proposed methodology and further improvement on the study can be done by monitoring applications. Finally recommendations were given based on research study outcome for real time applications.
- item: Thesis-AbstractOptimum pre-cooling guidelines: applicable to commercial buildings in Sri Lanka(2015-10-15) Narangoda, NAPSK; Attalage, RHVAC plants in buildings are generally started earlier than the building operation start time. That is to absorb the stored thermal energy in the building and reach the set indoor thermal condition by the time which the building operation is started. Cooling energy required during this period is called Pre-cooling energy and the early plant running time is called Pre- cooling time of the building. Thermal energy in buildings depends on pre-defined factors and predicted factors. Pre-defined factors include building envelope, envelope materials, type of HVAC system installed, Building interior, lighting, other internal heat gain factors, building operation pattern etc. Predicted factors include climatic condition in the region throughout the year. Due to the fact that precooling time is determined by both pre-defined and predicted factors, a thermal modeling study is more appropriate and recommended to assess the “pre-cooling demand and time” of buildings. The focus on this research study is to prepare an optimum “pre-cooling guidelines” for commercial buildings in Sri Lanka taking climatic variations also into account. World Trade center, Colombo, the largest commercial building in Sri Lanka was modeled in e-QUEST and results were analyzed with Colombo climatic data throughout the year to study the pre-cooling requirements (demand & time) and hence to derive a set of general pre-cooling guidelines applicable to any commercial building in Colombo.
- item: Thesis-AbstractPotential of cool thermal storage for an air conditioning system in a records repository building(2015-02-07) Seneviratne, LJ; Attalage, RIn Heating, Ventilation and Air Conditioning (HVAC), Cool Thermal Storage (CTS), is a popular demand side management technology for shifting electrical demand for cooling from peak time to off peak time periods in most of the countries in the world. However this technique is so far not successfully implemented for building air conditioning systems in Sri Lanka. This research study shows how CTS is used to reduce life cycle cost of air conditioning system for Record Repository Building (RRB) in Sri Lanka using CTS under “General Purpose Tariff” applicable for commercial buildings and “Industrial time of day tariff” applicable for industries and hotels in Sri Lanka. TRACE 700 software[3] is used to carry out a computer simulation for modeling of the air conditioning system of RRB for CTS for different scenarios such as partial storage, full storage etc against the base case of air conditioning system without CTS under “General Purpose Tariff” and “Industrial time of day Tariff”. It has been found that incorporation of partial ice thermal storage for air conditioning system of RRB the cooling capacity of chiller plants for the building can be reduced by 25% and thereby initial cost of air conditioning equipment including ice storage tanks could be reduce by 11% and maintenance cost including ice storage tanks by 8%. Further it has been found that the annual operating cost of air conditioning system incorporated with both partial and full CTS for RRB will be lesser than the annual operating cost of air conditioning system without CTS under General Purpose Tariff (Rate G.P-2) [16&17] as well as Industrial Time of Day Tariff (Two Part)- (Rate I-2 (T.D.2)) [16&17]. The life cycle cost for 20 years of both partial and full CTS for RRB will also be lesser than the operating cost of air conditioning system without CTS under General Purpose Tariff (Rate G.P- 2) [16&17] as well as Industrial Time of Day Tariff (Two Part)- (Rate I-2 (T.D.2)) [16&17]. The payback period for air conditioning system incorporated with full CTS for RRB is 8 to 9 years under General Purpose Tariff (Rate G.P-2) [16&17] and 3 to 4 years under Industrial Time of Day Tariff (Two Part) - (Rate I-2 (T.D.2)).[16&17] Key Words: Cool Thermal Storage (CTS), Record Repository Building (RRB), General Purpose Tariff (Rate G.P-2) [16&17] Industrial Time of Day Tariff (Two Part) - (Rate I-2 (T.D.2)) [16&17].
- item: Thesis-AbstractFeasibility of a cogeneration system in a medium size hotel in Sri Lanka(2015-02-07) Riyaaz, MH; Attalage, RBy cogeneration, electricity and thermal energy can be produced by one prime energy source simultaneously. Using cogeneration systems to provide electricity, hot water and chilled water for hotels and hospital buildings seems to be a perfectly logical solution. The principle of cogeneration systems is simple and the technology is both well known and reliable. It helps to reduce energy costs, better fuel utilization, improve plant energy efficiency, reduce electricity consumption due to absorption chilling and as a whole reduce greenhouse gas emission. In Sri Lanka, huge quantity of money is expended to import petroleum fuels for transportation, industrial, etc., and power generation purposes. Last year in Sri Lanka thermal power generation was recorded more than 60% of total power generations. However in thermal power generation, efficiency is normally less than 35%. Since cogeneration systems could produce electricity, hot water & chilled water, the overall efficiency could be more than 80%. To implement a cogeneration system in three star class hotels in this study, information and data was collected from several hotels in relation to the monthly total power consumption, annual occupancy and number of guest rooms. All of these hotels operate alike and are similar to the three star class hotel operations. Based on the collected data and information three different scenarios for the proper analysis have been considered. As a result of this cogeneration system, hotel saves 2,078 kWh electricity units per day and capital cost increased 25.7 million rupees, which can be recovered in less than the three years’ time. Further to that annually it saves 10 to 11 million rupees from the operational and maintenance costs when considering the scenario 2. In Sri Lanka 15% losses indicate for electricity transmission and distribution system. Subsequent to that, because of this system it is expected to saves 2,445 kWh per day and more than 800,000 kWh per year in this project. When considering the environmental aspect reduction of 400 tons per year of CO2 to the atmosphere.
- item: Thesis-AbstractA Study on factors affecting stress and its level of manageability among construction project managers in Northen and Eastern provinces(2014-07-03) Rajagopalasingam, V; Senaratne, SAlthough a number of studies of stress in occupational settings have been conducted over the past decades, there are relatively few studies relating to stress of construction project management. The present study examines to identify the critical stressors causing stress, to assess the level of stress and to explore the impact of stress on performance of construction project managers (CPMs). Primary data was collected through use of a written questionnaire distributed by postal mailing and hand delivered to 155 samples of CPMs who work in a variety of construction entities (sector wise) using stratified simple random sampling.115 questionnaires were returned in a usable form giving an overall response rate of 74%. An analysis of the data collection for this study was determined in three ways. As a first step Relative Important Indices and mean score were generated to identify the sources of stress. Besides, factor analysis has been conducted including reliability analysis to confirm the sources of stress. Next, Descriptive statistics of scoring mean and standard deviation were generated for required variables to assess the level of stress and then correlation calculation was generated to assess the impact of stress on performance of CPMs. Finally Chi Square tests were conducted to test the significance of these correlations. Four kinds of stressors (Task stressors, organizational stressors, physical stressors and personal stressors) and seven sources of stresses including work overload, poor role congruence, poor organizational structure, career development environment, poor work environment, work group cooperation and type A behavior of personality were identified among CPMs. Four types of stress were identified in this research: objective stress, subjective stress, burn out and physiological stress. From the analysis, low level of objective stress, moderate level of subjective stress, high level of burnout and moderate level of physiological stress were found among the CPMs. This study confirms the impacts of four types of stress on performance (task, interpersonal & organizational) of CPMs. Limitation and implication of these research findings were also discussed in this study. Finally it is recommended to hold stress management workshops for the CPMs to relax their stresses and employers are recommended to keep reviewing and monitoring the abilities of the CPMs and allocate the responsibilities and work load accordingly. Direction for further studies is also suggested.