| Abstract [eng] |
Rebuilding and modernization of existing buildings plays an important role nationwide. It is necessary to improve condition of buildings in order to reduce energy intensity. There are many ways to reduce energy intensity: modernization of heating and ventilation systems; application of energy-saving devices; replace of fossil fuel to renewable energy sources (RES). Most of the buildings around the world are still ineffective in terms of energy consumption. Currently more than a half of residential buildings in Lithuania are old and have poor energetic characteristics. An individual house is the second most popular type of accommodation; therefore renovation of these buildings could significantly reduce energy consumption at the national scale. Aim of the thesis is to analyze the measures to reduce consumption of primary and secondary energy in existing residential buildings, as well as to assess environmental and economic effects of these measures. Object of the thesis is residential individual buildings (existing buildings). The experiment was conducted with a standard 20 years old building (up to 200 m2), which already had some projects, aiming to reduce energy intensity. Methodology of the research includes few different techniques. All these techniques have the same major idea – to assess the measures to increase energy effectiveness of individual residential building: energy auditing, balance of materials and energy, balance of fuel and energy, implementation analysis of cleaner production (technical, environmental and economic assessment), assessment of environmental efficiency etc. The research included assessment of the building’s current condition and assessment of major problems, related to ineffective consumption of primary and secondary energy. Following the research, four alternatives are proposed to reduce the intensity of energy consumption, including the feasibility study of the alternatives. It is proposed to modernize the lighting system by replacing ineffective incandescent lamps to more effective LED lamps. Motion sensors are recommended for the rooms without any natural day light. It is also proposed to insulate the ground flooring above unheated space, modernize heat production system by switching to the RES and install solar energy collector for the production of hot water. Obtained results revealed that modernization of lighting system in residential building could help saving up to 87 % of electricity. Additional insulation of the floor above the unheated basement could help saving more than 20 % of building’s total heating energy. Transition towards the pellet fuel instead of a coal could help increase efficiency of heat production by 12 %, as well as reduce the loss of heat production, air pollution (down to 0.218 t/y) and emissions of the greenhouse gas (up to 100 %). Installation of solar energy collector system could help saving up to 620.24 kWh/y of electricity (up to 10 % of total consumption) and up to 1.037 MWh/y of heating energy (up to 3.7 % of total consumption). Comparative analysis of relative environmental indicators revealed that simultaneous installation of all mentioned innovations could help achieve significantly better results in the field of energy efficiency: energy intensity would reduce approx. 28 % (from 216.8 kWh/m2/y to 156.03 kWh/m2/y per useful space of the building). Analysis of the economic assessment results revealed that the project of electricity saving is a genuine project of cleaner production, which includes not only environmental effect, but also economic benefit and the payback period is up to 2 years. Economy of the pellet fuel installation is achieved only if the reduction of labour input is considered. However, despite of environmental benefit, payback period of the investment into insulation of the floor above the unheated basement is too long and other alternatives should be considered to reduce the intensity of heating energy consumption in the building. Also, use of solar energy collector for water heating is economically beneficial only when there are alternative ways to realize excessive heat energy in the warm season. |
