District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand

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... door temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Energy Procedia 126 (201709) 915-922 1876-6102 Abstract Nowadays, pollutant gases emitted from the civil aircraft are doing more and more harm to the environment with the rapid development of the global commercial aviation transport. Emissions of aircraft engines whose rated output is greater than 26.7 kN and whose date of manufacture is after 1 January 1986, are regulated under the provisions established by ICAO to guarantee that engines, at the reference emissions Landing and Take-Off cycle, do not exceed certain regulatory environmental limits. For this purpose, an analysis of the aircraft engine at Landing and Take-Off cycle conditions to determine the emission is important. The aim of this paper is to study the GE90-94B engine built on the proven success of the early GE90 engine models, that with a nominal thrust of 416.8 kN and a dual dome annular combustor, powers the Boeing 777-200 aircraft. The engine is modelled and simulated with the modular code ESMS, that has the ability to simulate a generic engine at design and off-design conditions without creating a new source program. A thermodynamic design simulation at cruise condition has been realized, using a few known operating characteristics and some general design parameters can be determined. Thereafter an off-design analysis varying the operating mode has been reported; consequently, the thermodynamic parameters as fuel consumption, thrust, bypass ratio, turbine inlet temperature and exhaust temperature change. Moreover, using the results of the ESMS simulations it is possible to estimate, with a correlation, the NOx emissions during the Landing and Take-Off cycle. Abstract Nowadays, pollutant gases emitted from the civil aircraft are doing more and more harm to the environment with the rapid development of the global commercial aviation transport. Emissions of aircraft engines whose rated output is greater than 26.7 kN and whose date of manufacture is after 1 January 1986, are regulated under the provisions established by ICAO to guarantee that engines, at the reference emissions Landing and Take-Off cycle, do not exceed certain regulatory environmental limits. For this purpose, an analysis of the aircraft engine at Landing and Take-Off cycle conditions to determine the emission is important. The aim of this paper is to study the GE90-94B engine built on the proven success of the early GE90 engine models, that with a nominal thrust of 416.8 kN and a dual dome annular combustor, powers the Boeing 777-200 aircraft. The engine is modelled and simulated with the modular code ESMS, that has the ability to simulate a generic engine at design and off-design conditions without creating a new source program. A thermodynamic design simulation at cruise condition has been realized, using a few known operating characteristics and some general design parameters can be determined. Thereafter an off-design analysis varying the operating mode has been reported; consequently, the thermodynamic parameters as fuel consumption, thrust, bypass ratio, turbine inlet temperature and exhaust temperature change. Moreover, using the results of the ESMS simulations it is possible to estimate, with a correlation, the NOx emissions during the Landing and Take-Off cycle.