One of the greatest issues nowadays is that of the urban heat island effect on the thermal conditions inside cities. The air temperature inside the city core is warmer than that in suburbs, thus deteriorating the quality of life for citizens and making outdoor spaces uncomfortable in terms of thermal comfort. This phenomenon is usually assessed in large scale cities worldwide and less often in medium-sized towns. The current study aimed to investigate the urban heat island effect and, therefore, to assess the outdoor thermal comfort conditions in a medium-sized city. More specifically, the methodology of the current study includes: (i) the combination of different monitoring techniques to quantify the urban heat island effect in a medium-sized Mediterranean city. Both in situ measurements and remote sensing techniques were applied to assess the urban heat island effect in terms of both the canopy layer (CUHI) and the surface (SUHI); (ii) the identification of the parameters that affect thermal comfort and the identification of the most appropriate bioclimatic indices that determine outdoor thermal comfort in the city of interest. Both questionnaire survey and in situ measurements took place on a sidewalk in the city of Xanthi, Northern Greece, during the summer. The CUHI effect was obvious, especially in the morning and afternoon. Downscaled MODIS satellite images also showed that the intensity of SUHI was higher in the morning and afternoon. Apart from air temperature, important differences in the values of most microclimatic parameters were recorded between the meteorological station placed inside the urban area and those gathered from a nearby meteorological station. The narrow roads, the thermal properties of construction materials, and the absence of greenery characterized the area of interest and may be the key factors creating these differences in climate. Concerning the thermal comfort assessment, the most significant parameters were the air temperature and solar radiation, although, both empirical and direct indices were found to describe the comfort values well. According to the results, downscaling techniques are also important for the SUHI effect to be investigating in detail in medium-sized urban environments.

School buildings apart from the shelter they provide they have an educational role as pupils have the opportunity to learn from their early educational steps how to become environmental friendly and aware of the energy consumption and its results. This consideration is nowadays increasing the concern throughout Europe and promotes sustainable solutions in school buildings involving energy-efficient technologies and measures. The energy performance of school buildings at the primary and secondary education level located at northern Greece is investigated in this article, covering the C and the D climatic zones. The mean energy consumption of all buildings was recorded at about 84 kWh/m². When the normalized energy consumption is considered, this value falls to a mean value of 41 kWh/m². Energy saving can be applied at school buildings providing considerable energy savings while improving indoor thermal conditions. School buildings have mainly heating energy needs and thus, it is important to investigate measures to reduce heating energy. Although schools operate for a short period during the cooling period, indoor overheating conditions can be avoided with simple and relatively inexpensive measures (proper shading, nigh ventilation, ceiling fans, external surface colour). With the EPBD recast demand for ‘Nearly zero energy buildings’ by 2018 for public buildings, the combined application of energy saving measures in order to reduce energy needs and RES systems to cover the remained energy needs allows for investigation of different systems combination in order to cover the varying energy needs according the size, shape and location of school buildings.

Ventilated wall structures can contribute to energy saving in the building sector. This article presents a study of the cooling performance of a ventilated wall component. The ventilated wall component was constructed in actual scale and tested under real weather conditions (summer) in an outdoor test cell. The testing configuration comprised the recording of the thermal behaviour of the ventilated wall with a fixed air gap width and with the addition of a radiant barrier. Several variations in the basic configuration were also tested, namely, different air inlet and outlet areas, the use of natural and mechanical ventilation on the air gap and the use of floating and controlled room air temperature regimes. The results demonstrated that the application of this technique reduces the cooling load of a building. Especially, a ventilated wall equipped with a radiant barrier and a mechanically ventilated air gap provided with the most beneficial results.

Windows are responsible for significant amounts of energy loss through typical building envelopes. There have been multiple studies on heat loss through the glazing unit and frame system. This study presents an experimental investigation of a window unit and focuses specifically on the conductance between the structural elements and the frame system of a conventional house in the city of Xanthi, northern Greece. It is obvious that even a perfect window system cannot reduce heat transfer between the base of the frame and the upper surface of the floor. The experimental and simulation procedure of this project includes the installation of an insulating layer in front of the window unit for a variety of frames (solid wood, aluminum, PVC, etc.) at different distances. The main objective of this paper is to determine how effective an insulating barrier can be in respect to different types of frame, glazing, and weather conditions for the control of heat loss. Through the application of this technique, in combination with an appropriate insulating frame and window unit, designers can control the temperature inside the room at close proximity to the windows, in order to contribute to energy saving, aiming towards a building with zero energy demand.