• Energy Research
• 0202 electrical engineering close

Abstract The goal of the paper is to compare two different methods of calculating the linear transmittance of thermal bridges in order to evaluate the building energy need for heating. As a case study, it was considered an existing non-isolated residential building of ‘70 years consisting of 30 housing units. All the construction details of the building are known. The energy analysis of the building was carried out using a commercial software. The linear transmittance of the thermal bridges was determined both by the catalogue, provided by the software itself, and by the numerical finite-element evaluation according to UNI EN ISO 10211 standard using a 2-D numerical simulator. Through numerical analysis it is possible to evaluate in a detailed way all the thermal bridges present in the building and therefore it is possible to evaluate the approximation induced by the use of the catalogue. Results show that the detailed analysis leads to a transmission heat exchange through thermal bridges about eight times greater than that estimated through the catalogue and consequently to a higher building energy need of about 12%. The heating energy needs per unit area of the individual housing units were also compared.

Abstract The aim of this study is to demonstrate the requirement to integrate the urban microclimate to predict the energy needs of buildings. To do this, an integrated approach in TRNSYS software was developed and compared with existing experimental results of a street canyon. Afterwards, a case study was carried out in the case of a street canyon located in the city of Tangier in Morocco. The impact of the aspect ratio on the temperature of the building surfaces and the radiation absorbed by them was examined. The results show that there is greater radiation absorption on the building facades in street canyons than on those of stand-alone buildings. These effects lead to higher surface temperatures in street canyons, resulting in increased cooling energy needs in summer and reduced heating energy needs in winter.

Abstract This paper presents new approach for determining buildings technical system energy performance. This new methodology describes a mathematical model for accurately predicting indoor temperature and heat losses of the space heating and domestic hot water system components. The entire model is described by system of ordinary differential equations which can be solved using standard numerical techniques. The innovative aspect of the method is the integral approach in mathematical modeling of buildings energy needs and technical systems heat loss, taking into account heat accumulation in all considered parts (building envelope + technical system). Such approach allows a detailed insight of the system behavior for chosen working conditions. This model can serve for energy performance calculations in a wide variety of buildings types and their technical systems. The calculation example is given for family house, equipped with conventional space heating and domestic hot water heating system, with the time step of 1 min and for characteristic day of each month within a year. The results are compared against those obtain from EN ISO 13790 and standard series EN 15316. The comparison shows significant differences in determination of the annual delivered energy to the heating system (33%), as a consequence of difference in estimation of the energy need for heating (15%) and calculation of the technical systems recoverable heat losses utilization factor, which seems to be underestimated. The delivered energy to the space heating and domestic hot water heating system differs 25%, while the energy delivered to the generation system differs 4%.

International audience; The purpose of this work is to study the possibility of obtaining a net zero energy building and producing fresh water via a solar still by using a hybrid PV/T water solar collector. A solar prototype built in the city of Boussaâda is studied under the climate of Ouargla city to show the importance of the use of passive solar architecture. The results highlight the importance of using passive solar techniques to reduce heating energy needs. Energy savings are realized with passive techniques even before the use of active solar systems. It is possible to cover the energy requirements with the use of hybrid PV/T water solar collectors. High solar thermal fractions for domestic hot water are achieved during the year. Solar electricity produced is high and can cover the annual needs of domestic hot water, air conditioning and heating, lighting and household equipment of the prototype. A part of the difference in area between that used to cover the thermal requirements of domestic hot water and the total area of the PV/T collectors is used for supplying a solar still. An increase in the annual production of 2.97 times is obtained compared to passive solar still.