The renewable energies are inexhaustible sources of energy obtained from Nature around, like the sun or the wind. These energies can be:
• Solar Energy The energy of the Sun can be converted into electricity or heat, such as photovoltaic or thermal solar panels for heating the environment or water;
• Wind Energy Wind energy that can be converted into electricity through wind turbines or wind turbines;
• Water Energy The energy of water from rivers, tides and waves that can be converted into electrical energy, such as dams;
• Geothermal Energy The earth's energy can be converted into heat for heating the environment or water;
The integration of renewable energiesin buildings is a challenge for which the aim is to design an efficient building that allows the incorporation of a system that captures the energy and turns it into a source of energy that is useful for the building. In reality, placing solar panels on the roof of the building, for example, is not an efficient measure of energy in itself, because if they do not take into account the efficiency of the building it may not even be enough to accommodate energy, more of the rest of the systems. Hence the importance of integrating renewable energy systems into energy-efficient buildings which up to that point have exhausted all possible passive design strategies in their design or which have included rehabilitation measures for energy rehabilitation and energy efficiency.
Incentives for the use of renewable energies and the great interest that this subject has raised in recent years are mainly due to the awareness of the possible scarcity of fossil resources (such as oil ) and the need to reduce emissions of harmful gases into the atmosphere, GHG ( Greenhouse Gases ). This interest is partly due to the objectives of the European Union, the Kyoto Protocol and concerns about climate change.
The use of renewable energies , such as solar thermal and photovoltaic panels, for the production of heat and electric energy from the use of solar energy, is a form for which Portugal has resources of great abundance, comparing the availability hours of sunshine per year with other European Union countries. However, these should be considered as complements to the architecture of buildings, which should not neglect the use of passive design strategies, such as the use of solar orientation, natural ventilation, thermal inertia and shading, among others. These strategies are a very advantageous solution due to the favorable climatic conditions to obtain greater sustainability in the buildings in Portugal.
The promotion of Energy Efficiency and the use of renewable energy in buildings has been done by the revision and application of Regulations, such as the RCCTE and the RSECE, and by the approval of the creation of an Energy Certification System, aiming at the reduction of energy consumption and corresponding CO2 emissions. According to data from the beginning of the 2000s DGE, about 22% of the final energy consumption of the country is represented by the buildings sector in the average annual consumption of energy in Portugal, where in the big cities this number rises to 36% . These figures have been increasing by some 3.7% in the residential sector and by 7.1% in the services sector.
Wind energy is growing at a rate of 30% a year, with a global production capacity of 158 gigawatts (GW) in 2009, and is widely used in Europe, Asia and the United States. At the end of 2009, cumulative global photovoltaics surpassed 21 GW and photovoltaic energy parks are common in Germany, Portugal and Spain. Solar thermal power stations operate in the US, Portugal and Spain, the most important of which is the 354 megawatts (MW) in the Mojave Desert. The world's largest geothermal facility is the Geysers in California with a nominal capacity of 750 MW. Brazil has one of the largest and most important renewable energy programs on the planet, involving the production of ethanol from sugar cane, ethanol gives 18% of vehicle fuels in the country. Ethanol gas exists in abundance in the USA.
Considering that many renewable energy initiatives are on a large scale, applied renewable energies are also suitable for rural areas where there is no electricity grid, where energy is generally crucial in human development. Globally, about three million households receive power from small photovoltaic systems. Micro-hydric systems are used on a large scale as villages or municipalities. About 30 million rural dwellings receive light and warm water made from biogas. Furnaces that use biomass as a source of energy are used by one hundred and sixty million households.
Local climate issues call for a change of attitude, coupled with high oil prices, peak oil prices, which only help governments raise prices, are increasingly creating vital legislation for the use of renewable energy, incentives and marketing it.
Renewable energy production costs are already at the global average, lower than fossil fuels and clean energy parks will be even more competitive by 2020. These are the key findings of a new study published by the London-based Carbon Tracker Initiative.
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