Master of Science in Building Services Engineering

Permanent URI for this collectionhttp://192.248.9.226/handle/123/12432

Browse

Now showing 1 - 19 of 19

item: Thesis-Abstract
Energy saving potential of ceiling fan-assisted air conditioning in tropical climates
(2024) Tennakoon, IE; Ranasinghe, RACP
The cost of air conditioning in tropical climates makes the biggest contribution to the energy bill in most domestic, commercial, and industrial settings. Improving the air circulation and thereby enhancing the thermal comfort of occupants pave the way to running the air conditioners (AC) at a higher temperature setting, which leads to lower power consumption. Accordingly, this research examines whether ceiling fan-assisted air conditioning systems can reduce the energy required for cooling in tropical environments. The research is primarily based on field studies and was conducted in a typical office space in Kankesanturei, Sri Lanka, which has a year-round tropical climate with high temperatures and high levels of humidity. The office room is air-conditioned with a window-type AC, and air circulation is provided by a ceiling fan. 50 participants with almost identical clothing were selected. Testing was conducted for different AC temperature settings and different speed settings of the ceiling fan. Wind speed, temperature profiles within the room, and corresponding energy consumptions were recorded. Thermal sensation feedback from participants was also obtained via a questionnaire for each operating condition. Measurements and participant feedback were analyzed, using established ASHRAE standards to rate the thermal comfort level. According to the findings, utilizing ceiling fan-assisted AC can result in a reduction in energy usage of up to 40% (depending on the AC type, temperature setting, and the nature of the occupants). As a result of the improved airflow generated by the ceiling fans, the hybrid system provides superior thermal comfort at moderate fan speeds. This is because the increased air movement improves air circulation and reduces temperature stratification within the room. Accordingly, this research highlights the potential benefits of adding this combined system to building design and HVAC system selection, providing significant information for building designers. Keywords: Fan assisted AC, Thermal Comfort, Air Conditioner, Ceiling Fan, Office buildings.
item: Thesis-Abstract
Development of an integrated intelligent building control system through an automated scenario based approach
(2024) Senarath, NDGD; Rodrigo, AS
Integrated Building Control Systems (IBCS) may consist of public address and pipe music systems (PAPMS), elevator management systems, fire/life protection and detection systems, CCTV systems, access control systems, and building energy management systems (IBCS). So, the Integrated Intelligent Building control system has a major influence on energy efficiency, indoor environmental variables/parameters, analysis & survey, health and safety. It is well acknowledged that an Integrated Intelligent Building control system may improve a building's environmental and economic performance. Basically, automated high-rise buildings can regulate /control its inside environment parameters using a computer in view of improved cost effective energy usage, building users satisfaction, safety, and productivity. Energy, Safety and comfort management, as the principal function of a high rice defence building control system, seeks to resolve the tension between increasing user wellbeing including safety and lowering building operating costs. This thesis presents a novel method for Intelligent Building Control systems that use an intelligent facility manager to autonomously regulate the building environment. This thesis discusses the present problems facing when constructing the Integrated Building Control System and further explains available and required facilities and the importance of acquiring information from sensors through common architecture with a common protocol (Communication language). Further, this describes how Building Control System architecture (including all required facilities) utilizes its sensory data to understand and identify exciting/ real time situations from the behaviour /scenario of persons and systems whilst always providing a fast, safe response to any situation. Finally, this report shows how deep can utilize this system for early warning and firefighting of high-rise defense building Keywords: Building Automation, Facility Management, Defence Building
item: Thesis-Abstract
Benchmarking water demand of low-income housing apartment complexes in Colombo, Sri Lanka
(2024) Gallage, SL; Ranasinghe, C; Jayasundara, R; Wijewardane, A
Along the main roads, Sri Lanka's coastline regions are fast urbanizing and expanding. The progress of these development works increased the population inside the urban areas, which created new social and economic issues. The high-density apartment complexes as high-rise apartment buildings are introduced to mitigate these social and economic issues. To maintain sustainable development in these urban areas, providing essential facilities for these apartment buildings is important. 70,000 low-cost housing units were scheduled for construction as part of the Urban Regeneration program and Sri Lanka's National Physical Plan (2011-2030). These plan to relocate the people currently residing in underserved areas of Colombo city. Providing the essential facilities for these apartments does not assure the sustainability of the development. Overuse and waste are also required to be minimized, and optimum usage of these facilities is also to be assured. As a result, efficient buildings that preserve the environment are necessary for sustainable development, and these services need to be standardized. There are building rating systems like LEED, BREEAM, and Green Star that are well recognized in this context. In Sri Lanka, the Green Building Rating system, UDA Green, is recognized to describe a building's efficiency. Energy efficiency is what these rating systems are primarily concerned with. Concerns about water efficiency are also significant in this context because Sri Lankan water demand benchmarks are not established, which makes it difficult for construction designers to create effective solutions for these structures and monitor the efficiency of the existing apartment buildings. The study of establishing a benchmark for the water demand of low-income housing apartments requires studying of socio-economic behaviour of this community. A survey questionnaire was used to collect the information required for this study from 500 randomly chosen sample residents spread over 18 low-income apartment complexes in the Colombo area. A benchmark for the water demand in apartment buildings for low-income housing was developed after the survey's results were analysed. The benchmark water demand values for low-income housing are 170.16 litres per person per day and 850 litres per apartment per day. Keywords: Water demand benchmarking, Low-Income housing apartments, socio-economic behaviour, Survey questionnaire
item: Thesis-Abstract
Potential energy saving with high at chilled water designs compared to the conventional low at design for office buildings
(2023) Joseph, AI; Wijewardane, A; Lekamwasam, S
This thesis investigates the potential energy saving benefits associated with high delta T chilled water designs compared to conventional low delta T designs in office buildings. This high delta T requirement specified in the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 90.1: 2016 under subsection 6.5.4.: “Chilled Water coil selection and theoretical background of temperature difference towards energy efficiency”. The aim of the study is to evaluate the capital cost reduction and annual energy savings achievable through the implementation of high delta T configurations and finally identify the applicability in tropical countries. The study followed a comprehensive research methodology that involved analysing 03 chilled water delta T options and assessing their impact on capital costs and energy consumption. The findings of the study demonstrate a significant cost savings and energy efficiencies associated with high ΔT chilled water designs. A total capital cost reduction of 2.8% for the ΔT=7°C system and 3.6% for the ΔT=8.3°C system was observed compared to the conventional ΔT=5°C system. Additionally, the annual energy analysis revealed a 0.97% reduction in energy costs for the ΔT=7°C system and a higher energy cost saving of 1.93% for the ΔT=8.3°C system compared to the ΔT=5°C system. These findings highlight the potential benefits of adopting high delta T chilled water designs in office buildings. The results not only demonstrate cost-effectiveness but also underscore the importance of energy efficiency and sustainability in building design and operation. The outcomes of this study contribute to the existing body of knowledge in the field and provide valuable insights for building professionals and stakeholders seeking optimal cooling system solutions. By embracing high delta T designs, practitioners can achieve tangible benefits in terms of reduced capital expenditures and ongoing energy consumption, leading to a more sustainable and economically viable built environment. Keywords: Energy efficiency, high delta T, chilled water, office building, tropical country
item: Thesis-Abstract
Condensate recovery from air handling units and fan coil units to reduce the water consumption by the air conditioning systems
(2023) Ragulakeethan, S; Wijewardane, MA; Lekamwasam, S
This study investigates the potential for reduction of makeup water consumption by recovering condensate captured from Air Handling Units (AHUs) and Fan Coil Units (FCUs) of central chilled water system in hot and humid climatic conditions. In conventional air conditioning systems, significant amounts of condensate is generated at different components and typically discharged as waste. The cooling towers are used to enhance the heat rejection efficiency of the condenser of the chilled water systems. Usually, it requires a significant amount of makeup water (2% of nominal flow rate) to replenish the regular water losses, mainly due to the evaporation. Therefore, the condensate collected from the AHUs and FCUs can be routed through the cooling tower, resulting in the reduction of potable water usage and to improve the quality of the cooling tower water. This paper presents a method to collect the condensate water and store it in a holding tank for later use in offsetting the cooling tower makeup water requirement. The analysis was performed by collecting the condensate from AHUs/FCUs of five different types of buildings in three different weather zones in Sri Lanka with varying climatic conditions. The findings demonstrate that condensate recovery can be an effective strategy to reduce the water consumption in central air conditioning systems, especially in regions facing water scarcity or high-water costs. The potential benefits of this approach include decreased water consumption, lower water bills, and a reduced environmental impact and eventually the overall energy consumption of the system. Keywords: Water conservation, Hot and humid climate, Condensate recovery, Makeup water, Central air conditioning system
item: Thesis-Abstract
Comparative study on chiller configurations in an efficient chilled water system in a tropical high-rise building
(2023) Iddagoda, PK; Wijewardena, MA
Energy-efficiency concerns have changed several design trends, and chilled water systems are now designed for different delta T values. The delta T affects the coil sizes of Air Handling Unit (AHU) and Fan Coil Unit (FCU), pumping power and pipe sizes of the chilled water distribution system and capacity of the chiller. Designing a chilled-water system for a higher delt T (ΔT), reduce the initial costs due to smaller valves, piping, pumps and also reduce the operating cost due to low chilled water flow rates. However, this topic is accompanied by a multitude of arguments and contradictions. This research was based on the comparative study of parallel flow and series counter flow (SCF) chiller arrangement for different ΔT values and finding the best chiller configuration and ΔT value with higher Coefficient of Performance (COP). For this comparative study, a high-rise commercial building was selected, and the chilled water system was designed by conducting cooling load calculations and appropriately selecting chillers and pumps. For two chillers with the same capacity configured in parallel and SCF arrangement, chilled water flow rate, chiller lift, and COP values were calculated for various ΔT values. Additionally, a comparative study was also done for the chilled water pump power and distribution system piping sizes for different flow rates. The CoolPack software was used for the calculation of COP values. Based on the study, it was observed that there was a decrease in chilled water flow rate as the ΔT increases. The analysis also revealed that compared to parallel flow chillers, SCF chillers have chiller lift reduction and higher COP for both conventional and high ΔT system. It also found that chiller lift does not depend on ΔT value and it only depends on chilled water supply temperature. The maximum COP was attained at a chilled water supply temperature of 9.0 0C which was the maximum supply temperature selected with 100C ΔT (beyond the 8.30C ΔT recommended by ASHRAE), resulting in a COP value of 6.60. There was an improvement in the COP value of 1.36 for 10 0C ΔT with a temperature range of 9-19 0C using the SCF arrangement compared to the conventional 50C ΔT with temperature range of 7-12 0C with parallel configuration. iii A reduction of about 50% in flow rate and pump power were observed for a 100C ΔT compared to conventional 50C ΔT. In this building, the percentage reduction in pipe sizes within the chilled water distribution system remains constant at 29.29 of % for a 100C ΔT compared to a 50C ΔT. The research concludes that utilizing design strategies such as higher temperature differences, elevated supply chilled water temperatures, and SCF chiller configurations can enhance the chiller efficiency, reduce pumping energy use, and piping installation costs, leading to overall cost savings for chiller system. Keywords: Conventional ΔT, High ΔT, Series Counter Flow Chillers, Parallel Chillers, COP, Chiller lift
item: Thesis-Abstract
Laboratory wastewater treatment using clay biochar composites in bio-geo filters
(2021) Pathinayaka, V; Bandunee, A; Manthilake, MMI
Laboratory waste is overlooked because of its low flow rate, despite the fact that it has a negative influence on the human and environmental systems. As a result, the focus of this research is on using clay biochar composites in horizontal flow bio geo filters to treat university laboratory wastewater in an environmentally acceptable manner. The composite was made with a 1:5, 1:3, 1:1, 3:1, and 5:1 mass ratio of Cinnamon biochar and Neem biomass to clay from Giant tank, Murunkan, Mannar for laboratory research experiments, and then treated with slow pyrolysis at 400°C. To determine the hydraulic retention period, adsorption kinetic studies and isotherms were performed, followed by the m/v ratio and COD test. For both Neem and Cinnamon, the Clay: Biochar mass ratios, 1:1 ratio composite exhibits superior efficacy in COD elimination. To ensure the presence of Montmonolite, clay samples were analyzed by Laser diffraction particle size analysis. As a result, clay samples taken from the Giant tank contain 3.42% and 4.99% nano clay, respectively. The existence of MMT in Murunkan clay is confirmed by FTIR readings of clay samples from Murunkan, which reveal a distinct and strong band at 998.03 cm-1 and 3620 cm-1. XRF analysis was used to assess the chemical composition of biochar samples. The use of biochar with a greater K content supports heavy metal sorption and phosphors retention. H/C ratios of Cinnamon and Neem biochars were 0.06 and 0.02 respectively, according to CHN analyses. BET study revealed that the specific surface area (SSA) of gasified Cinnamon Biochar was 563m2/g. As a result, it has a higher adsorption affinity. Kinetic model parameters for COD adsorption onto Neem - BC and Cinnamon - BC composites were determined using the most commonly utilized adsorption kinetic mathematical models. The removal effectiveness of adsorbent constructed of Neem biochar composite is better than that of Cinnamon biochar composite. The Bio Geo Filter was created using Subsurface Flow Constructed Wetlands design principles. For the treatment system, a composite sample of on-site stored wastewater was diluted to 1:100. The system is based on a mix of physical, chemical, and biological processes that occur naturally in wetlands and are linked to vegetation, sediments, and the microbial populations that live there. The removal effectiveness of the system for heavy metals (Cd, Cr, Hg, and Mn) was investigated, and all heavy metal concentrations in effluent were much lower than in influent. The effluent quality was assessed and compared to CEA criteria for inland surface discharge. When water travels through the systems and into the tanks, only phosphate levels increase. As a result, methods for using this by-product (Phosphate) as fertilizer must be developed. As a result, our newly designed cost-effective bio-geo filter treatment system is highly recommended for laboratory wastewater purification. Keywords: Laboratory wastewater, Murunkan Clay, Biochar, Constructed wetland, Bio-geo composite, Kinetic models & Isotherms
item: Thesis-Abstract
Investigating the factors affecting indoor air quality of office buildings in Colombo city_a case study
(2022) Lankanath EGG; Manthilake I
The wellbeing, comfort, and satisfaction of office occupants are all influenced by the indoor air quality (IAQ). As such, it is important to maintain good IAQ in offices. However, several studies say that Sri Lankans have a limited understanding of IAQ. As a result, the aim of this research is to identify the factors that influence IAQ. Through this study, it is also expected to gain a better understanding of indoor air pollutants, recognize issues related to low IAQ, and determine ways to improve IAQ based on in situ levels of indoor air pollutants. Following a walk through inspection, in situ measurements of IAQ were carried out in selected office spaces in Colombo, Sri Lanka, based on the findings of the literature review. Temperature (T), Relative Humidity (RH), Particulate Matters (PM2.5 and PM10), Carbon Monoxide (CO), Carbon Dioxide (CO2) and Total Volatile Organic Compound (TVOC) were selected as the IAQ parameters. In addition, an experiment was conducted in a real office environment to measure TVOC concentrations in the presence of air fresheners and incense smoke. Due to inadequate ventilation, the worst case of IAQ was found in office spaces which have no proper ventilation system. As a result, mechanical ventilation is appropriate to improve the IAQ of office spaces when natural ventilation is not possible. The key factors affecting IAQ in the selected office buildings of this study were identified as the location of the building, occupancy related activities, office equipment, and ventilation and air-conditioning system. To improve and maintain good IAQ levels in a country, it is essential to have IAQ guidelines. However, it has been found that IAQ guidelines are not available in Sri Lanka. Conducting research on IAQ is essential for developing the country's IAQ guidelines
item: Thesis-Abstract
A Case based approach to benchmark the energy and water consumption of supermarkets in Sri Lanka
(2022) Senanayake SMCP; Manthilake I; Wijewardane A
Buildings are responsible for about 40% of global energy consumption, 42% of global CO2 emissions and about 30% of global fresh water consumption. Therefore, the importance of energy and water consumption benchmarking in buildings has become a major objective for governments and relevant authorities. Since energy and water consumption patterns depend upon various factors such as climate conditions, personal habits, hygiene practices and economic factors, it is most suitable to develop local benchmarks for countries/regions instead of using global benchmarks to compare the performance of the buildings. The main intention of this research is to analyse the major research gaps in energy and water benchmarking in Sri Lankan buildings, and to develop water and energy benchmarks to bridge those gaps. Energy consumption benchmarks in Sri Lankan context are available for commercial sector, hospitality industry, apparel industry and tea processing industry, which are established by Sri Lanka Sustainable Energy Authority (SLSEA). However, energy benchmarks are not available in local context for retail (supermarkets), educational, healthcare and residential building sectors. Moreover, it is identified that, water consumption benchmarking is a major research gap in Sri Lanka, as the water consumption benchmarks have been developed only for hospitality sector. The focus of this study is to establish the energy and water benchmarks for retail sector (supermarkets) in Sri Lanka. During the study, electricity consumption data from 2008 to 2020, and water consumption data from 2018 to 2020 were collected from 101 supermarkets across the country. Annual electricity consumption, annual electricity cost and annual water consumption of these 101 supermarkets were analysed against the sales floor areas and total floor areas of the relevant supermarkets. According to the analysis, electricity consumption benchmarks for Sri Lankan supermarkets was estimated as 780 kWh/year/m2 per sales floor area and 465 kWh/year/m2 per total floor area. Moreover, the water consumption benchmarks was estimated for the Sri Lankan supermarkets as 247 L/year/ m2 per sales floor area and 137 L/year/ m2 per total floor area.
item: Thesis-Abstract
Effect of daylight harvesting on building lighting energy consumption
(2022) Ariyaratne LI; Rodrigo A
In the beginning, humans used architecture to protect their selves from nature and unsteady environmental conditions. However, with time, modern buildings become more complex, which need to fulfil the different types of functions [1]. So, humans started to concern more about the visual and thermal comfort and energy efficiency of modern buildings. Daylight is the perfect source of light that human has adapted with respect to evolution. So, daylight harvesting is highly concerned in modern building designs in order to enhance occupants’ visual and thermal comfort and reduce artificial lightings costs. Although this should be wisely done since entering direct sunlight to the building envelope could cause visual and thermal discomfort, increasing heat load which causes additional air conditioning costs. The effect of daylight harvesting depends on many parameters. Building location, building orientation, building geometry, seasonal variation of the sun, window to wall ratio, window glazing parameters, Solar heat gain coefficient, Window height, Building interior parameters, shading devices, and solar control mechanisms are a few major parameters, which affect the outcome of daylight harvesting. This research discusses the effect of Seasonal variations, building geometry, window to wall ratio and window orientation for a typical office building situated in tropical countries on daylight harvesting.
item: Thesis-Abstract
Effective septic management for condominiums and apartments in Sri Lanka
(2022) Samarakoon CM; Manthilake I
Sri Lanka is a developing country, where wastewater and septic disposal are not managed at its optimum level. 76% percent of the households equip with their own water sealed latrines for sanitation facilities and discharged septic mixture is collected to a septic tank. Periodical septic removal from the household storages are required at a cost. Limited space availability in urban dwellings, apartments and condominiums caused practical issues to the current practice of the septate removal. Management of variated amounts of septate is a challenging function because the capacities of the offsite treatment plants are inadequate in highly populated urban areas, effectiveness of the treatment facilities is not consistent due to lack of technical knowledge and improper maintenance. Poor handling of human waste is caused by contamination of faecal sludge in water reservoirs, disposal of human excreta and urine without converting them into usable or commercialized end products and huge burden to municipalities to handle septic in terms of economical and practical. Currently effective human waste management becomes a national level discussion. It is planned to conduct national level survey and review the techniques and technological status locally, regionally and globally and make recommendations for practical technology transfer. Other than that enhance the quality of the composting can be obtained from the human excreta to a fertilizer through nutrient addition and facilitate the adoption of new composting technologies to enhance the yield and quality and implement household and institutional level conversion of septic into compost are key concerns. As per the world health organization prevention of spreading of water borne diseases such as typhoid or cholera is difficult due to the faecal contamination of drinking water sources. More than two million of child deaths annually occur due to the pneumonia and diarrhoea globally. Most of the children living in poor or remote communities are facing this risk and to the facts that preventable diseases are not mitigated by effective interventions which are not provided equally to all communities. Managing human septic from domestic and commercial sources and urban run-off is largely a matter of proper treatment and disposal. In Sri Lanka 97% of the community is relying on water sealed latrines and septic tanks for sanitation while about 3% use sewerage connection. Large part of the country does not have treatment plants to disposal of faecal sludge safely. Further treatment processes to sanitized night soil is required before disposal or delivering as a fertilizer. Local authorities are simply collecting the content in the septic tanks and dump it into the available treatment plants where poor end product management. Current situation with septic disposal is grown adversely with the increasing the number of multi-storey buildings in the urban areas due to 90% of urban dwellers equip with onsite sanitation systems with water sealed latrines directed to the septic collection tanks or cesspits. This thesis conducted to find out ancient and latest techniques and technologies of septic management applicable to current practice in the Sri Lankan context. Data were collected from three distinct multi-storey buildings located within the Colombo municipal council and analysed the discharged volumes of the septic and way of disposal. Possibility of adaptation or implementation of ancient and latest technologies are discussed extensively based on the results on the results of the analysis. Properly treated faecal sludge with organic fractions of municipal solid waste has higher possibility to be used as an agricultural resource for farmers in the country. Currently use of faecal sludge as fertilizers and possibility of replacing the mineral fertilizers are not popular in Sri Lanka. Sustainable and appealing solutions are required to dispose human waste with the increasing population country. Research works and experiments in the relevant areas are required to extend and develop further to ensure the sustainable management of faecal sludge.
item: Thesis-Abstract
Investigation of factors affecting solar photovoltaic power generation in Sri Lankan context
(2021) Ariyadasa LPNI; Rodrigo A
Due to the fossil fuel prices and depleting storage capacity, as well as growing concerns about global climate change, the use of renewable energy (RE) on a national scale has become essential for any country in the world. Within the Portfolio of Renewable Energy, Solar energy generation become a most popular in small, medium and large-Scale installation. Presently, In Sri Lanka there are many solar PV installation program has announced to encourage both individual and nation scale consumers. Under the Ministry of Power “Soorya Bala Sangramaya” or Battle for Solar Energy was launched in 2016 to increase small scale solar PV installation capacity up to 1000MW in 2025. The ultimate target of Sri Lankan government is to set 100% renewable energy in 2050 as per report published in 2017 under Asian Development Bank, and United Nations Development Program. Accordingly, in 2050, Sri Lanka total PV installation capacity is expected to increase up to 16,000MW. The aim of this study is to look into the role of solar energy in building electrification and evaluate the key factors affecting for solar PV generation and study their energy optimization and efficiency improving method. This will help general publics who are wish to install solar PV plant or already installed in their premises to acknowledge and improve their solar power energy generation units without expanding their current system or planned solar power plant. Moreover, this will not only help domestic level solar PV plant installer but also industrial or utility scale plant. The research's findings provide valuable and useful knowledge for policy makers, solar PV consumers and utilities as Solar PV become most important part of Sri Lanka Energy generation Mix in present and future.
item: Thesis-Full-text
Analysis for optimization of energy efficiency in office buildings in Sri Lanka
(2020) Dilhan MKT; Perera KKCK
Energy 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-text
Critical evaluation on waterproofing practices in the industry
(2020) Bandara IKA; Ekanayake LL
Waterproofing 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-text
Technological 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 R
Demand 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.
item: Thesis-Full-text
Analysis of cooling tower performance of world trade center in Colombo
(2020) Wickramasinghe W.A.D.P.; Perera KKCK; Manthilaka MMID
Energy crisis first experienced in the world during 1975, since then it is ever rising phenomenon felt by every human being on earth. This is due to accelerated industrialization of the world and rapid growth of standard of living of people. Therefore, global Energy requirement is increased day by day deficit between energy available is increasing. It is felt that energy preservation is much more important than searching for New Sources. Sustainability has been introduced to building services to reduce waste of energy and provide for future. Green building concept is increasingly popular in terms of reducing fossil fuel usage and introducing alternative energy utilization. Reducing Carbon foot print of a building is the responsibility of the engineer in modern times to support the sustainability goals. Heating, Ventilating & Air conditioning (HVAC) systems in Commercial buildings accounts for 60% to 70% of their total power consumption. This thesis explores the possibilities of improving the configuration of cooling tower and optimization of the chiller plant. A central chiller plant for tall-building was analyzed for the effect of improving efficiency to enhance energy saving with varying cooling tower combinations and fan speed regulation. It was revealed that increasing the combination of cooling towers has a limitation of efficiency rise. However, reducing fan speed with increasing chiller combination prove to be success in the increasing efficiency of the chiller plant.
item: Thesis-Full-text
Potential of using variable air volume systems against constant air volume systems for medium size office buildings
Herath, HMSC; Attalage, R
It is a popular fact among HVAC designers that variable air volume (VAV) systems are energy efficient than more common constant air volume systems. Despite that information, when comes to the selection stage of the most suitable air side system for the project, the designers falter to suggest a VAV system to the client with the higher installation cost yielded by the VAV system in his mind. It is nice if he has the luxury finding the pay back of the VAV system after modelling the building and doing a simulation. But, in reality it is a time consuming and tedious task in a busy schedule. It will be immensely helpful if the HVAC designer can decide whether to go for VAV or Constant Air volume (CAV) by just a careful study on some straight forward facts of the building. Therefore, this research is focused on developing a guideline in to decide whether to go for VAV or CAV for a midrise office building. It was done with the help of TRACE 700 energy simulation software. Few sample buildings are modelled with TRACE 700 in few orientations and a comparison was done taking the CAV system as base design and VAV as alternative. Life cycle analysis is done using the present tariff structures of Ceylon Electricity Board. The results of this research are based on two defined parameters as solar gain factor (SGF) and occupancy diversity factor (ODF). SGF is defined as ratio of solar gain to total cooling load of the building which can be obtained by basic cooling load calculation. ODF is a measure of average occupancy variation of the building. Lower the ODF value means higher the occupancy variation. The building category underwent to this research is mid-rise office buildings (i.e. height between 18m – 30m) and the ODF value for those buildings are between 64% and 80%. For a highly varied occupancy schedule, ODF is 64% and for a uniform occupancy schedule, it is 80%. For those ODF value range, the VAV benefited SGF value range is identified as 11.9-13.4 for a payback period of five years. That means, for a mid-rise office building, VAV system is benefitted for a SGF value range of 11.9 – 13.4. If the SGF is lower than 11.9 in a mid-rise office building, VAV systems are not economical when considered for a payback period of five years or less. For any SGF value in above range, the life cycle payback period can be determined using above linear relationship between SGF and life cycle payback period for a selected ODF value between 64% and 80%. For any exception with ODF values higher than 80%, a complete building simulation should be carried out to determine the required SGF value for that building. Otherwise, the investment for VAV will not be paid back within reasonable time (within five years as considered in this study). On the other hand, for a building with lower ODF than 64%, the investment on VAV is worth even in a SGF value lower than 11.9. Further studies should be carried out for the situations out of those ranges. The significance of some non-quantitative benefits of VAV systems is also highlighted.
item: Thesis-Full-text
Electrical energy saving potential in Sri Lanka office buildings : application to office buildings in Colombo
Priyantha, LHWKS; Attalage, R
This research study is focused on the applications to find out the potential cost effective energy saving measures (ESMs) to make projection of EUI (Energy Unit Intensity) values in kWh/m2.year for high rise office buildings in Colombo, Sri Lanka, as it is a widely accepted fact that energy efficient building design measures and techniques are application specific. Therefore, the objectives of this thesis include detailed study in relation to office building energy efficient measures (EEMs) and also study for office building energy saving potential using established Baseline Building parameters. This helps to quantify ‘office buildings energy saving potential’ and make projection of building energy consumption savings for new office buildings. This also helps to find out the potential energy saving measures to make projection of EUI values for office buildings in Colombo, Sri Lanka. The results of this research are based on two selected office building applications in Colombo. The building categories subject to this research are one high-rise office building (height around 100m) and one medium-rise office building (height around 30m) in Colombo. Life cycle analysis is done using the present tariff structure of the Ceylon Electricity Board. In most of the projects, the building sites are selected before the involvement of the design team. Also, within the limited site area, the building is orientated and the outer appearance of the building also finalized in order to maximize the useable capacity and aesthetics. Therefore, due to the above project constraints, some ESMs for building form such as aspect ratio of the building, orientation (reduced East-West faced windows) and WWR (window to wall ratios) are not considered in investigation. The analyzing of the potential ESMs for the selected office buildings are limited to the following energy saving measures due to the project specific limitation mentioned above, current industry practices, modeling software analysis limitations, owners of the buildings planning to rent out the spaces to outside tenants, time frame limitation of this study, viz., Selective glazing for windows, Perimeter circulation space, Open office space at perimeter, Daylighting through windows, Energy efficient lamps and ballasts, Lighting controls and High Efficiency cooling equipment (i.e. efficient chillers). TRACE 700 computer simulation software is used for modeling the buildings as it is a detailed simulation tool that computes building energy use based on the interactions between climate, building form and fabric, internal gains, HVAC systems and day lighting integration. It has been found that incorporation of cost effective energy saving measures (ESMs) for high-rise office buildings in Colombo, Sri Lanka have greater potential to reduce annual electrical energy consumption by minimum 20 percent in comparison with a Baseline Building and it can also establish better EUI values for high-rise office buildings in Colombo, Sri Lanka. Based on this study, it has been established that the EUI value for the high-rise office building in Colombo is 124 kWh/m2.year and EUI value for the medium-rise office building in Colombo is 83 kWh/m2.year. Further it has been found that the payback periods for selected cost effective ESMs are between 2.3 and 3.8 years under Ceylon Electricity Board (CEB) present tariff structure (General Purpose tariff). It is recommended that further research be carried out in this area for both computer modeling and data collection from existing office buildings in Sri Lanka to establish a better and more precise EUI values and higher annual energy saving percentage for office buildings in Sri Lanka, as this study is limited to few ESMs and computer simulation has been done for only two office building applications.
item: Thesis-Full-text
Study on Variable Refrigerant Volume Air-conditioning System
(2015-10-16) Vitharana, SKP; Attalage, RA
During the last two decades, air-conditioning has become a basic requirement in industrial, commercial and residential sectors. With the widened use of air-conditioning in all the sectors, the human community has faced serious environmental and socio economic problems. Prevailing energy crisis and ever increasing energy pieces has made the situation worst. Under the scenario, various novel technologies have been emerged to the airconditioner market. Variable Refrigerant Volume (VRV) air-conditioning technology is also considered as an advanced technology developed to cater the need of efficient use of energy for air-conditioning. The major objective of the research study was to analyze the suitability of VRV airconditioning system, analyze the actual saving potential and cost effectiveness of VRV airconditioning system compared to the other available types of air-conditioning systems and access the maintainability of VRV air-conditioning system. The study was conducted at a selected representative installation namely at the Sovereign Residences of Central Bank of Sri Lanka. Summary of findings are as follows, • VRV air-conditioners are suitable for medium scale hotel applications. However, this conclusion cannot be generalized for all the installations and the appropriate air-conditioning system for particular building should be selected only after performing a comprehensive analysis of energy performance of considered options on that particular installation (preferably after a computer simulation and life cycle cost analysis of different options). Therefore, though the demand for VRV airconditioning system is prevailing due to the higher efficiency rating and the part load performance of the air-conditioning appliances, the desires of the purchases on energy saving potential of VRV air-conditioners could be satisfied only when it is selected for an appropriate application. • Saving potential of VRV air conditioners could be high as 18 % compared to the energy consumed by split air-conditioning systems when used for appropriate applications. Therefore, the VRV system can be considered as a potential candidate for the installations where the building occupancy and cooling load are regularly varying. Further, Chiller (Central) air-conditioning system can also be considered as a potential candidate as it performs almost efficiently as the VRV system. It consumes around 4 % more energy than VRV system. Study on VRV Air conditioning system Abstract v University of Moratuwa • Computer simulation (Equest) shown that VRV air-conditioning system is the most efficient option among the potentially applicable options considered for the building. However, the Life Cycle Cost (LCC) analysis shows that Chiller system is the most economical air-conditioning system for the same building. Therefore, it is vital to perform LCC analysis in addition to performance analysis when selecting the appropriate air-conditioning system for a building. • Maintainability of the VRV air-conditioning systems is acceptable. It is necessary to select the correct density and thickness of the refrigerant pipe insulation to minimize the possibilities of formation of condensation along the refrigerant pipes. Also, the power quality should be maintained at an acceptable level to ensure the durability and proper functionality of electronics of the VRV air conditioning equipment.

Browse

Recent Submissions