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It is important to understand how the climate is changing in order to prepare for the future, adapt if necessary, and, most importantly, take proper precautionary measures to alleviate major negative impacts. This work investigates the potential impacts of climate change on the anticipated energy performance of the existing Hellenic building stock until the end of the century. The assessment considers average climatic projections for two future time periods, one for the near and one for the distant future, following two representative concentration pathways (RCPs). The first one is a baseline scenario (RCP8.5) representing the highest greenhouse gas emissions. The second is an intermediate stabilization scenario (RCP4.5), assuming the imposition of conservative emissions mitigation policies. The future climate data are generated for 62 cities throughout Greece. As a case study, the work focuses on Hellenic non-residential (NR) whole buildings, analyzing available data collected during about 2500 energy audits of real NR buildings. The available data are used to assess the buildings’ heating and cooling demand and energy use. The annual average air temperature for Greece in 2050 is projected to increase by 1.5 K for the RCP4.5 scenario and by 1.9 K for the RCP8.5 scenario. In 2090, the increase is estimated to reach 1.7 K and 4.2 K, respectively. Accordingly, if the existing NR buildings are not renovated, the average heating energy use is expected to decrease by 22–26% in 2050 and by 23–52% in 2090. On the other hand, the average cooling energy use is expected to increase by 24–30% in 2050 and by 28–66% in 2090. Full article

In an effort to reduce the operational cost of their dwellings, occupants may even have to sacrifice their indoor thermal comfort conditions. Following the economic recession in Greece over recent years, homeowners have been forced to adapt their practices by shortening heating hours, lowering the indoor thermostat settings, isolating spaces that are not heated or even turning off their central heating system and using alternative local heating systems. This paper presents the results from over 100 occupant surveys using questionnaires and walk-through energy audits in Hellenic households that documented how occupants operated the heating systems in their dwellings and the resulting indoor thermal comfort conditions and actual energy use. The results indicate that the perceived winter thermal comfort conditions were satisfactory in only half of the dwellings, since the actual operating space heating periods averaged only 5 h (compared with the assumed 18 h in standard conditions), while less than half heated their entire dwellings and only a fifth maintained an indoor setpoint temperature of 20 °C, corresponding to standard comfort conditions. Mainstream energy conservation measures include system maintenance, switching to more efficient systems, reducing heat losses and installing controls. This information is then used to derive empirical adaptation factors for bridging the gap between the calculated and actual energy use, making more realistic estimates of the expected energy savings following building renovations, setting prudent targets for energy efficiency and developing effective plans toward a decarbonized building stock. Full article