English

An urban park located in a densely built area of  Western Athens, Greece is monitored. Temperature data from 15 urban and suburban stations are also used to perform comparative analysis at the city level. The park presents an important temperature inhomogeneity during day and night due to the variable radiative cooling capacity and shading potential between its various zones. Average nocturnal Cool Island Intensities (CII) against the reference urban stations varied between – 0.7 K to – 2.8 K while during the daytime the maximum CII was between -0.2 to -2.6 K.

Τhe present article deals with the development and testing of photovoltaic pavement for heat island mitigation. The scope of this study is to evaluate its contribution to the balance of the Urban Heat Island phenomenon. For this reason, we made a photovoltaic pavement for purely experimental reasons (dimensions 3.5x1.3m) that consists of two different voltage polycrystalline photovoltaic panels. On top of them, a triplex security glass with a nonslip silk screen, PVB standard 1.14 mm was placed.

The present article deals with the energy classification and the environmental evaluation of the school buildings in Greece. The energy performance of the school buildings, in relation to the normalized annual consumption for heating regarding floor area and climatic conditions, was rated using clustering technique (K-means algorithm) and an energy classification tool developed. The audited school buildings were classified into five energy categories.

The improvement of the urban microclimate combined with the reduction of the energy loads is a highly important target that requires the research and development of innovative solutions with advanced thermal and optical properties. Color changing thermochromic coatings being reflective in summertime and absorptive in wintertime can address to the demand of lower surface temperatures and lower cooling loads. The interaction though with the solar radiation results in the breaking of the chemical bonds and the degradation of their performance.

Surface temperature measurements were performed in a deep street canyon, during summer period, in the center of Athens. Surface temperature was measured on an hourly basis, at several spots, in the external facades of buildings, pavements and at ground level inside an urban canyon. At the same time experimental data of air temperature were collected through extensive monitoring at four different heights in the center of the urban canyon. Based on these measurements air temperature vertical stratification was analyzed and interpreted as a function of the coating used.

The treatment of roof space with cool paint or vegetation is a widely employed urban heat mitigation strategy. As the allocation of roof space for social activity becomes more prevalent in the urban environment, there is a need to understand how cool roofs and green roofs can affect the outdoor thermal comfort of its users. 

Airtightness and controlled ventilation are important factors affecting energy use and indoor air quality. Airtightness tests were carried out on nine naturally ventilated social houses in Ireland. Subsequently, four of the houses were retested following energy efficient upgrading. The upgrading largely consisted of improving fabric insulation and where required the mandatory installation of passive wall vents. Interviews were conducted with the occupants to gain their perspectives of airtightness and ventilation in their homes.

Within the framework of the Dutch participation in the IEA Annex XIV" Condensation" field experiments have been carried out to study airborne moisture transport in realistic circumstances. The experiments were done in an unoccupied 3-storey dwelling in Leidschendam in the Netherlands. Some of the results will be discussed in this paper.