Group items tagged

Heat loss from buildings has a considerable share in waste of energy especially in Turkey since no or little insulation is used in existing and new buildings. Therefore, energy savings can be obtained by determining of heat loss characteristics with using proper thickness of insulation. For this purpose, in this study, calculations of optimum insulation thickness are carried out on a prototype building in Bursa as a sample city. Considering long term and current outdoor air temperature records (from 1992 to 2005), degree-hour (DH) values are calculated, and the variation of annual energy requirement of the building is investigated for various architectural design properties (such as air infiltration rate, glazing type, and area). Then, the effects of the insulation thickness on the energy requirement and total cost are presented. Based on life cycle cost (LCC) analysis, the optimum insulation thicknesses are determined for different fuel types. As a conclusion, the length of the heating period is average 221 days, and the mean heating DH value is found as 45 113.2 besides changing between 38 000 and 55 000. The optimum insulation thicknesses for Bursa vary between 5.3 and 12.4 cm depending on fuel types. In addition to this, the variation in Turkey is more dramatically.

The prospects for urban wind power are discussed. A roof-mounted ducted wind turbine, which uses pressure differentials created by wind flow around a building, is proposed as an alternative to more conventional approaches. Outcomes from tests at model and prototype scale are described, and a simple mathematical model is presented. Predictions from the latter suggest that a ducted turbine can produce very high specific power outputs, going some way to offsetting its directional sensitivity. Further predictions using climate files are made to assess annual energy output and seasonal variations, with a conventional small wind turbine and a photovoltaic panel as comparators. It is concluded that ducted turbines have significant potential for retro-fitting to existing buildings, and have clear advantages where visual impact and safety are matters of concern.

This comment aims at critically analyzing some of the economic efficiency issues that are raised in the paper by Muñoz et al. [2007. Harmonization of renewable electricity feed-in laws in the European Union. Energy Policy 35, 3104-3114] on the harmonization of feed-in law schemes for renewable electricity in the European Union. We comment on the choice between green certificate systems and feed-in laws, but pay particular attention to the implementation and design of a harmonized feed-in law scheme. In the comment we argue first that the approach suggested by Muñoz et al. tends to downplay many of the practical difficulties in assessing the real costs facing investors in renewable electricity, not the least since the presence of regulatory uncertainty about the marginal costs of renewable electricity may be essential for the choice between different support systems. Concerning the benefit side of renewable electricity promotion, the Muñoz et al. (2007) paper builds on an interpretation of the EU Renewables Directive that provides plenty of room for national priorities and that therefore essentially implies that harmonized support premiums per se are of little value. We argue instead that a harmonized system should primarily address the international spillover effects from renewable electricity promotion, not the least those related to improved security of supply in Europe. There exists then a strong case for disregarding the specific national benefits of renewable electricity production in the design of harmonized support systems, and for instead considering international-perhaps at the start bilateral-policy support coordination based on entirely uniform support levels.