Currently, buildings are considered to be a continuously evolving organism that over time has to be treated, rehabilitated, and upgraded to meet the requirements set by the user at a certain stage. Buildings are a central element of the EU member states' energy efficiency policies, accounting for about 40% of final energy consumption, and 36% of greenhouse gas emissions, and about 75% of buildings are not energy efficient. Recent applications and studies establish that green retrofitting has maintained older existing buildings to increase energy efficiency, optimize building performance, increase occupants' satisfaction, and boost economic return while decreasing greenhouse gas emissions. In this regard, this chapter aims to address the main factors that negatively affect the performance of residential buildings and presents the common green retrofitting measures that can be taken to ensure the state of human well-being in residential buildings.
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At a time when energy, environmental, economic and social concerns are becoming more important, being represented by climate change or those that jeopardize energy security, resource exhaustion or human health, reducing energy consumption along with human comfort and well-being in the buildings sector is of strategic importance, both at national and international level. Besides the efforts to development of new high-quality buildings which assures a high level of comfort to the building’s occupants while complying with the conditions of energy and environmental efficiency, it is essential to address an attitude towards human well-being and healthy environments, along with the decrease in high energy consumption levels in the context of rehabilitation of existing buildings.
Green retrofitting of the existing building stock is essential, not only to meet national energy efficiency targets, but also to meet the medium and long-term climate change objectives and move towards a sustainable, low-carbon economy by 2050.
By making a significant contribution to the EU's energy consumption, conventional energy use and carbon dioxide emissions, as well as a number of factors that can adversely affect occupants' health, the buildings sector is the subject of many policies and objectives in the medium and long term to reduce the negative impact on the environment. Aims formulated by the 20-20-20 target by 2020 are the set of three key objectives for:
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Reduction by 20% from EU's greenhouse gas emissions compared to 1999 levels.
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Increasing the share of energy produced from renewable sources in the EU by 20%.
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Improving the energy efficiency in the EU by 20%. (MDRAP, 2017b)
As the European energy system faces an increasingly pressing need for sustainable, affordable and competitive energy supply for all citizens, the European Commission adopted on 30 November 2016 the legislative package “Clean Energy for All Europeans”, through which is aimed the implementation of strategies and measures to achieve the objectives of the Energy Union for the first ten-year period (2021-2030), notably for the EU's 2030 energy and climate objectives, and refers to: energy security, energy market, energy efficiency, de-carbonisation, research, innovation and competitiveness.
In a wider perspective, the EU set a set of long-term objectives in roadmaps until 2050 (COM, 2011). Regarding the building sector, the main three roadmaps are:
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The EU’s objective for transition to a competitive low carbon economy by 2050 (COM, 2011a), which identified the need to reduce by 88% - 91% the carbon dioxide emissions from the residential and service sectors (collectively called the real estate sector) by 2050 compared to 1990 levels.
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The Energy Perspective 2050 (COM, 2011b), through which “increasing the energy efficiency potential of new and existing buildings is essential” for a sustainable future.
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An Energy Efficient Europe Plan (COM, 2011c) identifying the real estate sector as one of the top three sectors responsible for 70% -80% of the overall negative impact on the environment. Achieving better constructions and optimizing their use would reduce by over 50% the amount of raw materials extracted from the underground and could reduce water consumption by 30%.
These roadmaps are a long-term aspiration that is not only desirable from a social and economic point of view, but also ecologically essential and human health, safety and well-being in buildings.
Existing EU Buildings Fund: It is estimated that there are 24 billion m2 of useful floor space in the EU, Switzerland and Norway. According with the Buildings Performance Institute Europe (BPIE, 2011), for the analytical purposes, the European countries have been divided based on climatic, building typology and market similarities into three regions, illustrate in Table 1. In comparison to China and the US, Europe has the highest ‘buildings density’ (building floor space over land area) followed by China and then US.