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. Abstract Biomass conversion by gasification process is increasingly becoming attractive, especially for ceramic making industry, to transform biomass materials into combustible fuel gas called producer gas. This producer gas can then be used to fully or partially substitute liquefied petroleum gas in ceramic firing process. However, air gasification is known to generate low calorific value of gaseous fuel (3-6 MJ/Nm 3 ) which may not be able to generate sufficiently high temperature (> 1200 o C) flame required by ceramic firing process. Use of oxygen enriched air is therefore of great interest if medium to high calorific value producer gas is required. In this work, a modified equilibrium model of global gasification reactions is developed to predict the resultant distribution of combustible gas species in the producer gas and to study the effect of operating parameters (oxygen content in air, and equivalence ratio) in a gasification process of agro-residues in a fixed bed downdraft gasifier at a fixed temperature. The modified equilibrium model of global gasification reactions developed in this work is based on thermodynamically stoichiometric approach due to its simplicity and reduced computational time. Model predictions of reaction kinetic constants for gasification reactions and gas concentration are validated by comparing with available experimental data. Simulation of influence of oxygen content in air (21-50%) and equivalence ratio (0.15-0.35) on composition of combustible gas and its heating value is carried out. The preliminary model simulation is found to give good qualitative prediction of experimental results. For maximum calorific value of producer gas generated, oxygen content in air should be 50%, and the equivalence ratio should be 0.15, respectively. For better accuracy of this modified equilibrium model, unconverted char and tar should be further considered. Abstract Biomass conversion by gasification process is increasingly becoming attractive, especially for ceramic making industry, to transform biomass materials into combustible fuel gas called producer gas. This producer gas can then be used to fully or partially substitute liquefied petroleum gas in ceramic firing process. However, air gasification is known to generate low calorific value of gaseous fuel (3-6 MJ/Nm 3 ) which may not be able to generate sufficiently high temperature (> 1200 o C) flame required by ceramic firing process. Use of oxygen enriched air is therefore of great interest if medium to high calorific value producer gas is required. In this work, a modified equilibrium model of global gasification reactions is developed to predict the resultant distribution of combustible gas species in the producer gas and to study the effect of operating parameters (oxygen content in air, and equivalence ratio) in a gasification process of agro-residues in a fixed bed downdraft gasifier at a fixed temperature. The modified equilibrium model of global gasification reactions developed in this work is based on thermodynamically stoichiometric approach due to its simplicity and reduced computational time. Model predictions of reaction kinetic constants for gasification reactions and gas concentration are validated by comparing with available experimental data. Simulation of influence of oxygen content in air (21-50%) and equivalence ratio (0.15-0.35) on composition of combustible gas and its heating value is carried out. The preliminary model simulation is found to give good qualitative prediction of experimental results. For maximum calorific value of producer gas generated, oxygen content in air should be 50%, and the equivalence ratio should be 0.15, respectively. For better accuracy of this modified equilibrium model, unconverted char and tar should be further considered.