Browsing by Author "Pathirana, SM"

Now showing 1 - 8 of 8

item: Conference-Full-text
An assessment of rooftop solar pv policies and domestic energy use: scenario of Sri Lankan residential sector
(2017) Pathirana, SM; Halwatura, RU
The net metering scheme in Sri Lanka has experienced a fast diffusion due to the economic, social and environmental benefits for the consumers and the country. This paper examines the changes in energy consumption behaviour of the solar PV consumers after the installation. Further, this analyses the reasons behind the consumption change and the issues associated with the change. According to the study results, 69% of the respondents have increased the consumption up to more than 400 kWh and the tendency of previously low consumed customers to have higher post consumption is significant. Although, the existing net metering scheme favours the social, environmental and economic conditions of the consumer, the increase in the night time peak is the main issue associated with it. The study proposed three policy options; time of use net metering, battery pack and net metering attached with payment scheme, which need to be integrated to achieve a sustainable net metering scheme
item: Thesis-Full-text
Development of a sustainable energy rating system for residential buildings in Sri Lanka
Pathirana, SM; Halwathura, R; Rodrogo, A
Energy rating system can be considered as a key policy instrument that will assist the government to reduce energy consumption. Energy rating includes the direct bene ts such as, energy requirement and carbon dioxide emission reduction, cost reduction for the users, increase the public awareness regarding energy issues, and improve the availability of information regarding the building. The government of Sri Lanka also has identi ed the importance of energy performance of buildings and considers it as a strategy for the sustainable energy development of the country. Existing rating systems in the world only considered limited factors related to energy consumption and to provide more accurate rating system it is proposed that a more sustainable energy rating system should be developed considering all the criteria. This research is aimed at identifying the existing rating systems, investigate the existing systems, to identify the parameters required for determining the energy performance of residential buildings, to develop and equation for calculating the energy score and to develop a scale for comparing the energy performance of residential buildings in hot and humid climate in Sri Lanka. To achieve the above mentioned objectives, this research followed the concept of sustainable energy which comprises of both energy e ciency and renewable energy. The energy e ciency of a residential building needs to consider the energy e ciency due to building properties and energy e ciency of the occupants. To evaluate the energy e ciency of the building properties, the asset rating method was used where the building is modeled and the energy consumption for thermal comfort and lighting is calculated. Using 4569 di erent models (varying window to wall ratio, orientation, zone size, zone location, building shape and oor area), a parametric analysis was conducted to develop an optimum model which was then used as the reference value for the rst sub rating (Building consumption rate). A questionnaire survey was conducted to identify the factors a ecting the energy consumption of the Sri Lankan residential buildings and in total 336 lled questionnaires were used for parametric analysis. The questionnaire revealed that the number of bedrooms is not signi cant for energy consumption and the occupant characteristics and the equipment usage are highly signi cant factors. Therefore, when developing the occupancy behaviour rate, the average domestic energy consumption in Sri Lanka was used as reference, without normalising. To consider the renewable energy usage, another sub rating named energy source rate was developed and to decide whether to o set the energy consumption with renewable energy use or to use a separate index, another questionnaire survey was conducted with rooftop solar PV consumers. The results of the survey indicated ii that there is a strong rebound e ect due to the solar PV adoption and there are some other social and technical impacts as well. Therefore, when developing the energy source rate, a sustainability index was used and based on the percentage of contribution of the energy sources to the nal energy use the nal energy source rate was determined. These three sub ratings were normalised and brought to a common scale of 0 to 100. The sub ratings were integrated using weightages which were obtained using a perception survey of engineers, architects, quantity surveyors and facility managers in the industry. The application of the rating method is explained using two actual examples. Further, a sensitivity analysis was done to re ect the e ect of the changes in the parameters used in the score calculation equation using the rst sample house. The rating methodology proposed in this thesis can be used over any country or any building by changing the reference values and weightages. Keywords: Energy rating; energy e ciency; buildings; thermal comfort; renewable energy; energy labels; consumer behaviour
item: Conference-Abstract
Indoor thermal comfort and Carbon Dioxide concentration : a comparative study of air conditioned and naturally ventilated houses in Sri Lanka
(2017) Pathirana, SM; Sheranie, MDM; Halwatura, RU
Carbon Dioxide (CO2) is considered as a useful and easily measurable indicator for the ventilation and air quality of the indoor environment. Although this pollutant itself is not causing serious health issues with lower concentration and short durations, the higher concentration can indicate the lower ventilation level and possible air contamination with other pollutants. The study compared the naturally ventilated and air conditioned bedrooms in terms of thermal comfort and CO2 concentration. For naturally ventilated bedrooms, the temperature and the humidity level was higher than the air conditioned bedrooms. All the air-conditioned houses, including the houses with larger floor area and volume, build up higher CO2 levels which are more than the recommended concentration level. The CO2 level of the air conditioned houses significantly vary with the room size, number of occupants and the ventilation. For the studied air conditioned houses, no fresh air intake was provided mechanically. However, this air tightness has drastically increased the CO2 concentration, especially with smaller floor area. The air-conditioned houses have to compromise in order to achieve the higher energy efficiency with an acceptable level of indoor air quality. Maintaining the air change rate at 0.5 ach level would minimise the health risk due to CO2 emission.
item: Conference-Abstract
Investigating the adaptability of existing building energy rating systems to sri lankan residential buildings
Pathirana, SM; Halwatura, RU
Energy represents a considerably higher percentage of running cost of a building and also affects the optical and thermal comfort of the occupants. Despite the fact that the investment for buildings is higher than most of those equipment, only developed countries and few developing countries have developed their own energy ratings or certifications for buildings. Nevertheless, energy efficiency in building sector is utmost important as it accounts more than one fifth of annual energy consumption worldwide. Energy efficiency rating system can be considered as a key policy instrument that will assist government to reduce the energy consumption. Energy rating includes the direct benefits such as, energy requirement and CO2 emission reduction; increase the public awareness regarding energy issues; cost reduction for the users and improve the available data for the building. Studying the existing energy rating systems is very much important prior to the development of energy rating system for Sri Lanka. This paper examines 12 existing energy rating systems and analyses the adaptation opportunities for emerging Sri Lankan energy labelling system. The existing rating methodologies including asset and operational rating, parameters used for developing the energy rating and the comparability matrix were compared and discussed in this review.
item: Conference-Full-text
Optimization of thermal comfort in sri lankan residential buildings
(IEEE, 2018-05) Karunathilake, WKUV; Halwatura, RU; Pathirana, SM
The aim of this study is to evaluate the thermal comfort state in residential buildings in Sri Lanka and to study the possibility of getting them into the comfort zone without air conditioning. Located near the equator, Sri Lanka has a tropical climate with high temperature and relative humidity level. Therefore, the need of having a thermally comfortable living environment is a must in these conditions. A case study approach has been made in this study to evaluate the research problem. The selected 14 case study houses were optimized using Design-Builder, energy simulation software. The evaluation results highlight that the comfort level of the houses can be improved using mud concrete blocks as the external wall material and clay tiles as roofing. The optimisation results further indicate that thermal comfort level of the residential buildings in Sri Lanka can be achieved without using air conditioning if designed properly
item: Conference-Full-text
Optimum utilization of daylighting in office buildings
(IEEE, 2021-07) Babalagama, VHMS; Pathirana, SM; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Maximizing day light usage to occupant's comfort level is a modern energy saving technique for most aspect of a sustainable building management system. Due to tropical climate condition in Sri Lanka using a high window to wall ratio is not an effective method of daylight harvesting in modern buildings. This research introduces experiential optimization of daylight usage in an office building tor educe energy in t he occupant's comfort zone. Using the software Design-Builder 4.8 with energy plus to demonstrate the dynamic role of simulation tool in this case study. The selected case is a four-story building of total area of 3441 square meters and external window area of 1053 square meters overall. The longest side of the building oriented to east-west. There is a problem of direct sun light and heat inside the building according to its high window to wall ratio. This research helps to determine the consequence of effect of direct sunlight simulation and total energy to be compared with three stages. Optimize the day light harvesting providing 1.5 meters width sunshades along with providing three types of window films. Best optimization results of 6 7% energy saving f or the sunshade along with reflective tint comparatively a ssume that all the windows closed in basic model.
item: Thesis-Abstract
Pricing strategy auditing for garment manufacturing companies in Sri Lanka
(4/6/2011) Pathirana, SM; Heenkenda, NK
The Sri Lankan garment manufacturing industry needs to become competitive in terms of pricing with the phasing out of the Multi Fibre Agreement and threat of losing the GSP+ advantage. However, it is difficult for the garment manufacturing companies to identify their weaknesses in pricing due to lack of information on competitor’s prices and thus it is difficult to improve the pricing area.//This study focuses on Sri Lankan apparel manufacturing industry and it reviews the pricing practices in garment manufacturing industry. The current pricing process of the garment manufacturing industry was identified using literature review, interview, questionnaire and observational studies and discussed in the thesis. This also includes the analysed data of the questionnaire survey which was designed to identify the current pricing methods and it was concluded that the Sri Lankan garment manufacturers are using either purely cost plus pricing or a hybrid pricing system with cost plus pricing with slight market based approach.//Further this thesis includes a SWOT analysis which was used to identify the weaknesses and the possible improvement in existing pricing system, when developing the alternative pricing strategies. The study identifies some possible alternative pricing strategies in the forms of pricing models and some detailed cost estimation models to use with them. Further the study builds a pricing audit system which facilitates the garment manufacturing companies to identify their current pricing strategies and to identify the areas of improvement
item: SRC-Report
Pricing strategy auditing for garment manufacturing companies in Sri Lanka
(2010) Pathirana, SM; Heenkenda, NK
The Sri Lankan garment manufacturing industry needs to become competitive in terms of pricing with the phasing out of the Multi Fibre Agreement and threat of losing the GSP+ advantage. However, it is difficult for the garment manufacturing companies to identify their weaknesses in pricing due to lack of information on competitor’s prices and thus it is difficult to improve the pricing area. This study focuses on Sri Lankan apparel manufacturing industry and it reviews the pricing practices in garment manufacturing industry. The current pricing process of the garment manufacturing industry was identified using literature review, interview, questionnaire and observational studies and discussed in the thesis. This also includes the analysed data of the questionnaire survey which was designed to identify the current pricing methods and it was concluded that the Sri Lankan garment manufacturers are using either purely cost plus pricing or a hybrid pricing system with cost plus pricing with slight market based approach. Further this thesis includes a SWOT analysis which was used to identify the weaknesses and the possible improvement in existing pricing system, when developing the alternative pricing strategies. The study identifies some possible alternative pricing strategies in the forms of pricing models and some detailed cost estimation models to use with them. Further the study builds a pricing audit system which facilitates the garment manufacturing companies to identify their current pricing strategies and to identify the areas of improvement.