Background of Research

Climate change is defined as the alteration of the general state of the climate for a prolonged period of time (Met Office, 2012), typically induced by the increase in concentration of greenhouse gases (GHG) within the atmosphere due to man-made activities, and is thus acknowledged as the most significant environmental threat facing the world (DECC, n.d.). The global average air and ocean temperature rise, the changes in rainfall patterns, the sea-level rise and the melting glaciers, are some of the prevailing results of climate change (IPCC, 2007; Met Office, 2012).

GHG emissions increased by up to 80% between 1970 and 2004 (IPCC, 2007). It is acknowledged that even if the GHG concentrations remained at the 2000 levels a further global warming of about 0.1°C per decade would be expected. The European Union (EU) countries have committed to a GHG reduction of 30% on average relative to the 1990 levels, until the year 2020 (UNFCCC, 2013). Industrialisation and urbanisation influence the human settlements, microclimates and life. It is projected that by 2025 the urban inhabitants will reach five billion (Kolokotsa et al., 2009). The so called heat island phenomenon results further in higher air temperatures relative to the rural suburbs; cities today face inadvertent climate modifications (Oke, 1978; Mihalakakou et al., 2004).

With the emergence of climate change, energy shortage, population increase, indoor air quality (IAQ) health related problems, global recession and fuel poverty, authorities have now recognised an urgent need to reduce energy consumption within sustainable development. It is now main concern of governments to improve the environmental building performance with appropriate legislation (Emmitt and Ruikar, 2013).

The domestic sector in the Mediterranean country of Greece corresponds to the 80%

of the existing Greek building stock (I. Theodoridou et al., 2011) and has the highest

Chapter: 1 | 2 energy consumption in Europe (Asimakopoulos et al., 2012). The 2011 census documented up to 4 million multi-storey apartment buildings in Greece (EL.STAT., 2012) of which 50% were constructed before 1979, the year of the Greek energy regulations were introduced (I. Theodoridou et al., 2011). According to the Hellenic Statistical Authority in 2010, Greek construction activity is currently in a deep depression due to the economic situation of the country, facing up to 62.4% drop from 2008 levels (Theodoridou et al., 2012). The new building permits have been significantly reduced, reaching in 2011 the one fifth of the 2005 levels, while up to 98% of the Greek citizens do not intend to construct or buy a new residence within at least a year (SATE, 2012). The construction and refurbishment rate of buildings has fallen drastically (Papamanolis, 2015a).

The EU building sector accounts for approximately 40% of the total energy consumption required for provision of heating, cooling, lighting and appliances. The energy required for cooling in hot climates has been predicted to be more than double the energy required for heating (Santamouris and Asimakopoulos, 1996).

Residential buildings consume more electricity than other sectors, such as industry, and a little less than commercial buildings (IEA, 2011). There is a continuous increase in air-conditioning (A/C) installations (Yun and Steemers, 2011) especially in the southern EU countries (Geros et al., 1999). Research in Greek dwellings has shown that up to 70% of occupants operate A/C systems during summertime and up to 45% use fans (Drakou et al, 2011). All these highlight the significant potential for energy savings if natural ventilation strategies were implemented. The strong link between occupants and householder needs (73% of occupants being the homeowners (ELSTAT, 2012)) further demonstrates the substantial potential for energy savings.

The discouraging facts of the Greek Governments’ Gazette for the period 1990 and 2000 show up to 23% increase in three basic greenhouse gas emissions (CO₂, CH4, NO) (F.E.K., 2003) and demonstrate the country’s inability to meet the target set in Kyoto to reduce the Greek emissions by 25% relative to the 1990 levels by 2012 (Theodoridou et al., 2012). There is an increased need to promote energy conscious design, energy responsive behaviours and low carbon technologies in the Greek context. Cultural sustainability, economic initiatives, and environmental and social aspects of sustainability, should be considered along with minimising waste and energy consumption and avoiding low indoor air quality, as well as maximising occupants’ quality of life and ethical practice (Emmitt, 2012).

Chapter: 1 | 3 Building designers often turn to traditional architecture and techniques for lessons in making climate and environment work to their advantage (Kimura, 1994; Canas, 2004; Stasinopoulos, 2006; Serghides, 2010; Foruzanmehr and Vellinga, 2011).

Vernacular knowledge should be treated as a great source of know-how, integrating locality and sustainability into modern buildings (Asquith and Vellinga, 2006).

Heat waves in hot climates contribute to increase in mechanical cooling peak load demand, threatening to disrupt supply (Kolokotroni et al., 2007). Fuel poverty in relation to both cooling and heating demand has been reported at more than 20% of Greek households (M Santamouris, Kapsis, et al., 2007). Atmospheric pollution in Greek cities remains a significant factor affecting comfort in open urban spaces, despite a number of measurements to achieve EU targets for greener cities (Ministry for the Environment, 2009). However, the concentrations of common air pollutants have been recently reduced as reported by (Papamanolis, 2015b). Air-tight buildings and reductions in ventilation rates have led to reported concerns over IAQ (M Santamouris, Argiroudis, et al., 2007; Lai et al., 2009).

Given the warm, dry climate of Greece (Psomas et al., 2014) with the lowest levels of relative humidity and the highest wind speeds in the Mediterranean, it is possible to deliver occupants’ thermal comfort utilising natural ventilation strategies (Santamouris and Asimakopoulos, 1996). Increase in ventilation rates could significantly improve the indoor environmental quality of the dwellings (M Santamouris, Argiroudis, et al., 2007). Natural ventilation should be considered at the early stages of design as well as during refurbishment studies of existing buildings to ensure resilience to future climates.

Ventilation is necessary for IAQ (removal of stale air, odours and harmful chemicals), for provision of natural cooling (excess heat reduction), and for removal of heat and pollution at localised sources (Cook, 1998; CIBSE, 2005). Natural ventilation provides direct human comfort and/or decreases internal daytime temperatures by cooling the thermal mass during nighttime (Givoni, 1994). Natural day and night ventilation is utilised in different ways, via envelope opening configurations, with inclusion of wind-catchers, solar chimneys, dynamic façades, and wing-walls. Direct or indirect evaporative cooling strategies could be exploited to provide further passive cooling by water evaporation.

Chapter: 1 | 4