Master of Science in Building Services Engineering
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Browsing Master of Science in Building Services Engineering by Subject "BUILDING SERVICES ENGINEERING-Dissertations"
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- item: Thesis-Full-textAnalysis for optimization of energy efficiency in office buildings in Sri Lanka(2020) Dilhan MKT; Perera KKCKEnergy consumed in the building sector consists of residential and commercial end users and it accounts for 20.1% of the total delivered energy consumed worldwide [22].Global primary energy demand is projected to increase by annual rate of 1.6% between 2004 and 2030[23]. There are building codes, Standards, Guidelines etc. to regulate and promote energy efficiency in building sector [page 33]. Sri Lanka also had focused on minimising these increasing trends during the past decade. “Code of Practice for Energy Efficient Buildings in Sri Lanka 2008” was introduced as an initiative. Sri Lankan government is carrying out various programmes, seminars and activities to encourage building owners, developers, designers to implement energy saving measures. In this research three commercial buildings in Colombo region having 8, 8 & 10 floors and total floor areas of around 35 000 ft2, 60 000 ft2 & 90 000 ft2 and monthly average energy consumption around 50 000 kWh, 70 000 kWh & 100 000 kWh were selected. The study and analysis were done to find out whether there are none-compliances of the selected buildings with ASHERAE 92.1-2007 standard and Code of Practice for Energy Efficient Buildings in Sri Lanka-2008 which are used by professionals in the subject and to find out whether there are opportunities to improve energy efficiency of already constructed buildings further by modelling those buildings in Trace 700 software by simulating various possible options. None of the three selected buildings fully complied with the standards considered. Major weak points were poor building envelope sealing, insufficiency of usage of automatic controls, improper balancing of systems, poor lighting system efficiency , higher lighting power density and higher Solar Heat Gain Coefficient of vertical glazing. Though Building Automation Systems (BAS) are installed, it was revealed that by adding/upgrading some new features/options to BAS and by eliminating the weaknesses found, there are still more opportunities to increase energy efficiency further significantly.
- item: Thesis-Full-textCritical evaluation on waterproofing practices in the industry(2020) Bandara IKA; Ekanayake LLWaterproofing is the process of rendering an object or surface resistant to water. Importance of waterproofing in construction cannot be overstated. It is essential for durability, hygiene and also for a pleasant appearance. Water tanks, reservoirs, ponds, planter boxes, sewerage plants, water treatment plants, swimming pools, basements, roofs, bathrooms, kitchens, floors, balconies, tunnels, silos, parking decks, bridge decks, ducts, parapet walls and foundations all require waterproofing to last longer and to secure its aesthetic appearance. Also, there are several factors to be taken into consideration when selecting the most suitable waterproofing system for the required structure. The selected waterproofing system should be non-toxic, economical, permanent, easily applied, highly resistant to water, stable at a range of temperatures, compatible, resistant to bacterial & other growth and also provide a good texture. There is a proper procedure to be followed before applying any waterproofing system on the surface. First of all, inspect the area and get accurate information about the site. Then measure the right area and calculate the correct material requirements. Next prepare the substrate effectively. Weak areas such as cracks, honeycombs and joints, etc. have to be repaired. Then seal around the pipes/protrusions. Lay a sloping screed (if required) and fillets at right angled edges. Now apply the waterproofing system strictly conforming to the manufacturer’s specifications. Cure the waterproofing system as specified. Various reasons may lead to failures in waterproofing. Some of them are application of an unsuitable waterproofing system, using incorrect application tools, incorrect mixing proportions, poor storage of waterproofing materials, poor substrate or surface preparation, bad maintenance practices, application under direct sunlight or during rain and failure to protect application from other sources.
- item: Thesis-Full-textTechnological potential of small scale Ice thermal storage based air conditioning system in the generation phase for hotel & entertainment industry of Sri Lanka(2020) Godamunne RWSMS; Attalage RDemand for electricity during a day, varies with the time due to various factors. Electricity demand of Sri Lanka for a typical day could easily be divided into three main categories. One segment characterizes a very high sudden demand increase during later in the evening, and sharp decrease of the demand during the mid night until the next day early morning time and average daily demand during the day time. As a remedial action in facing this change of demand, electricity service providers generally encourage users to reduce the demand through different measures and also shift their consumption during the high demand period to the low demand period. This is achieved by introducing different electricity tariffs based on the time of the day. As Air Conditioning systems demand considerable percentage of building electricity consumption, Cold Thermal Storage technologies is an ideal candidate for electrical load shifting applications of buildings. This study explores the technological feasibilities and also reviews the engineering economics of building small scale Ice Thermal Storage based air conditioning system in the generation phase which has average capacity of 32 Ton Hours. The development of small scale thermal storage based air conditioning system is progressed through a detailed research work and final design was reviewed of its economic feasibility to be used for hotel rooms & 100 capacity movie theaters under Hotel & General electricity tariff structures respectively. This study further investigates in particular the ice building process in a water filled, limited length horizontal rectangular enclosure with the constant temperature glycol circulation system at the top & bottom surfaces. The rates of ice building on top and bottom surfaces were mathematically modeled based on the equations published by Et al. P. Bhargavi & Et al. Liang Yong. The dimensionless equations were then converted to dimensional and set of equations were derived to find the ice thickness Vs time, temperature profile along ice thickness at a given time and several other associated parameters necessary to calculate the heat transfer during water freezing. The goal was to find the maximum achievable ice thickness during 6.5 hours period and total energy extracted by the glycol circuit. Three glycol temperatures of -12C, -6C and -3C were considered and 3 data sets were built. By considering a given glycol temperature, the built ice thickness was calculated and tabulated for 6.5 hours period at 20 minutes intervals. Thereafter the temperature profile along the ice thickness was tabulated during the end of each 60 minutes (1 hour) up to 6 hours and final data set was tabulated at the end of 6.5 hours. Here the temperature profile was estimated at every 2.5 mm distance along the built ice thickness. The width & length of water filled rectangle enclosure was selected as 10 cm & 110 cm respectively and this unit is called Primary Ice Making Chamber. The height was selected based on the final built ice thickness which was decided based on temperature v of glycol circuit. Finally relevant total energy extracted and final ice volumes were calculated for 3 different glycol circuit temperatures. In order to achieve the uniform ice thickness inside the Primary Ice Making Chamber, counter flow arrangement was introduced to glycol circuits placed at top & bottom surfaces of it. Still there is a drop of final ice volume. The volume reduction was calculated and relevant total energy removed by the glycol circuit was calculated. This was repeated for 3 different glycol temperatures. The glycol circuits were designed and relevant flow rates were calculated to maintain the heat transfers for 3 designs scenarios. Finally 3 ice thermal storage designs were evaluated. The cost of manufacturing was calculated for all three designs. The operational cost was calculated for all three cases under hotel tariff for using at hotels and under general tariff for using at Movie Theaters. It was revealed that the price of chiller contributes to more than 50% of the cost of manufacturing for all 3 designs. The payback period for the use case of hotel rooms under hotel tariff was found to be 4.3 years. The use case of Movie Theater has a 3.4 years payback period. This clearly indicates the further possibility of reducing the payback period under both cases used by cutting down the capital cost of chillers. When these units are manufactured on an industrial scale, it would further reduce the cost of chillers by volume discounts. This study makes a clear indication that small scale ice thermal storage systems are economically feasible.