1 Introduction

The built environment comprises buildings, infrastructures and open spaces and it is the final result pf many social, environmental and financial processes that serve and fit with the needs and the standards of the local society. Several economic, financial pressures and environmental influences related to labour demand and offer, properties, equity and related investments, family income, fabrication distribution and consumption of goods, human and local identity and cultural heritage, security of the population and land use, energy and resources flow determine and define the characteristics of the urban human communities. The building sector has very dynamic characteristics and a quite complex nature. Its main objective is to protect and when possible improve the life quality of population, generate wealth and employment opportunities but at the same time it produces wastes and pollution, consumes tremendous quantities of materials, resources and energy and affects the climate of cities and the globe and compromises the survivability, vulnerability and poverty of human communities. Essentially, yje built environment and its components act as the catalyst promoting future developments and trends at the technological. Social and environmental level.

The built environment is facing several challenges. Among them, overpopulation, poverty, excessive energy consumption, pollution and waste management, regional and global climate change. Seems to be the most important one. Despite the important challenges, continuous progress and development transforms gradually challenge into opportunities supplying the dynamic development of the human communities.

This chapter aims to present in a brief way three of the main problems of the built environment, energy consumption, regional climate change and energy poverty. Also, to articulate ideas on the potential benefits for an eradication of energy poverty, mitigation of regional climate change and minimisation of the energy consumption. Most of the material is drawn from references (Santamouris 2016, 2019, 2010), where readers can get more detailed information and documentation.

2 Energy Consumption and Buildings

The present chapter concentrates on the characteristics and the energy consumption of the building sector in Europe. Residential buildings consume almost 27% of the total consumption in the Continent while the commercial and in general the tertiary sector is responsible for an other 14% of the total European consumption. The high share of the residential sector is mainly due to the total area of residences, 18 billion m2 and almost 75% of the total building stock, with an average floor area around 87 m2 per residence.

The average energy consumption of Buildings in Europe is around 220 kWh/m2/y, and varies between a maximum around 320 kWh/m2/y for Finland and 150 kWh/m2/y for Bulgaria. In parallel, the average energy consumption of the tertiary buildings around to 295 kWh/m2/y, while the corresponding average consumption of the residential building is close to 200 kWh/m2/y. Tertiary buildings are characterized by a constant and increasing energy consumption trend due to the annual evolution of the services by 1.3%. The increase consumption rate of the tertiary sector is close to 1.1% during the last 10 years. In parallel, the electricity energy consumption of the tertiary buildings has increased by 60% during the recent years. Among the most consuming tertiary buildings are office and trade buildings, responsible each for about 26% of the total commercial consumption. It is estimated that the continued rise of the services sector in commercial buildings will surge a total consumption increase of the sector up to 93% by 2030. Despite the continuous decrease of its absolute energy consumption caused by the technical improvements and the strict legislative measures, space heating of premises is the most consuming energy component.

Strict energy legislative measures applied and implemented the recent years have contributed to a continuous increase of the energy efficiency in the residential sector. Despite the increase of the energy efficiency, the residential sector has increased its energy consumption the last 20 years by 14%. The observed Increase of the energy of the residential sector is due to the considerable increase of the residential stock, the rise of the attributed living space per person and also because of several social, political, technological and financial measures and reasons.

Because of the high heating performance of the new residential buildings in Europe, that represents almost 20% of the total residential stock, the specific consumption for heating purposes in the residential sector has decreased significantly, close to 15% the recent years. Consumption data shows that new residential buildings may consume up to 60% less heating energy than buildings built before 1999. The reduction f the specific heating consumption is much higher in the Nordic European countries, between 50 and 60%, while in the Southern countries the corresponding decrease of the heating demand is between 20 and 30%.

The consumption of energy in buildings is highly impacted by social, environmental and mainly on serious economic factors and variations. As revealed from the recent perturbations of the energy consumption, it is evident that the building sector is very sensitive in economic changes and variations. Because of serious economic problems, population may partly satisfy energy needs and finally reduce significantly the final energy demand. It is underlined that because the financial crisis of 2007–2015, in Greece, households reduce their energy consumption by 4%. Similar results and characteristics are also observed in other European countries with economic problems like Ireland, Portugal and Slovakia. In these countries, the decrease of the energy consumptions was as high as 22%.

3 Urban Regional Climate Change

Regional climate change, or urban overheating, is a major issue for most of the large size cities in the world. There are more than 400 cities in the world where the problem of urban overheating is experimentally documented. The magnitude of urban overheating may exceed 8–9 C with an average values between 5 to 6 C. Urban overheating is the result of the more positive thermal balance of cities compared to their surrounding suburban or rural environment. In parallel to the urban overheating, heat waves have increased their magnitude and frequency all over the world. The synergy of heat waves with urban overheating increase further the ambient temperature and intensify urban overheating.

Higher ambient temperatures have an important impact on the energy consumption for cooling purposes, while increase the levels of heat related mortality and morbidity, rise the levels of urban pollutants and in particular of the harmful ground level ozone, put in risk and decrease the quality of live and the survivability of the low income households while have an important economic impact in the quality of life of urban citizens.

Urban overheating is extremely well documented in most of the European cities. In parallel, its impact on the energy demand and heat related mortality seems to be tremendous. Urban overheating is more intense in the low income neighborhoods of the European cities and place under threat the life of vulnerable urban population.

4 Energy Poverty

Energy poverty refers to the situation in which families lack a materially, economic and socially level of energy consumption and global energy services and necessitated level of energy services. Energy poverty is a serious threat for the low income population in Europe and the world. According to the official statistics there are about 100 to 150 million of energy poor in Europe that can not afford to satisfy their basic energy needs and pay their bills. As a result, energy poor live under very low and very high indoor temperatures during the winter and summer period.

Energy poverty levels are quite high in many European States with quite low GDP. It may exceed 30% of the total population. Energy poverty results from a combination of factors like the excessive energy prices, the insufficient family income and the inadequate quality of dwellings. Many recent statistical studies have demonstrated that vulnerable European citizens use to live in dwellings of poor energy performance. While about the 10% of the population in Europe lives in dwellings with serious energy and environmental problems, the corresponding percentage increases up to 25% for the low income and vulnerable population. According to the European statistical services, between 20 and 55% of vulnerable and low income households in Southern and Eastern Europe live in residences with leaking windows. In parallel, statistics show that in the UK, almost 17% of the households of lower income use to live in completely inappropriate dwellings. Presenting mould and condensation. The ratio between low income to the high income population is close to three. Additionally. More than 1,966,000 dwellings, or 8% of the stock in the UK suffer from excess cold problems.

5 Minimizing to Zero—A New Sustainability Objective for Europe

Minimizing to zero is a concept aiming to develop a strategy able to minimize or eradicate completely the impact of harmful defects, emissions, wastes, etc. The main objective of the strategy is to minimize the energy consumption of buildings, eradicate energy poverty and mitigate as much as possible climate regional and global climate change. This can be achieved through the development and implementation of advanced innovative technologies combined with appropriate economic. Social and environmental policies.

It is evident that such a strategy is very radical and far from the actual reality and practice. However, it is evident that the idea is very appealing, it incorporates high level moral and humanistic features, is an unequivocal choice, and can be the ultimate road map of future strategies and developments.

The main objectives and goals of such a strategy deals with:

  1. (a)

    the energy consumed by the building sector,

  2. (b)

    the impact of buildings on the regional climate change and in particular with urban overheating

  3. (c)

    the potential eradication of energy poverty in the built environment.

Such ambitious goals should be achieved gradually. Even a partial satisfaction of these objectives could contribute highly to improve the quality of life in human societies. However, the whole strategy needs an excellent planning and the development of an agenda on the necessary technological, social and economic innovations that have to be designed and implemented. This requires a considerable investment made in the global building sector that should result in the development of new future opportunities and will generate serious medium and long term societal benefits, and will alleviate people from the specific problems.

It is widely accepted that the energy consumption of buildings can be seriously reduced through the use of advanced technology. The necessary financial investments to minimize the buildings energy consumption in Europe by 2050 are estimated between 14.5 and 23.6 trillion of Euros. It is also estimated that the CO2 emissions of the residential and tertiary sectors will be limited by 90.3% and 87.7% compared to 2005, respectively. In parallel, the implementation of innovative energy measures will create about 189 jobs per million of Euros invested

Future measures aiming to minimize the buildings energy consumption is propose to focus on the following:

  1. (a)

    Rise the global energy performance of the building energy systems to considerably limit the energy consumption and the final energy needs,

  2. (b)

    to use renewable energy to cover the remaining energy demand,

  3. (c)

    to optimize the operation of the environmental and energy building systems through the implementation of smart and intelligent technologies.

6 Conclusions

Recent research efforts aiming to improve technologies for the building sector, have resulted in the development and commercialization of building related technologies that minimize the energy consumption of buildings while contribute to mitigate the amplitude of the regional urban overheating. The development of advanced envelop protection systems, the high efficiency HVAC systems, the high performance technologies based on the use of renewable energies, as well as well as technologies of cool and super cool materials aiming to increase the albedo of cities are among the more promising technologies to improve the environmental and energy performance in the built environment. Photonic and plasmonic materials as well as materials of high reflectivity, can be used in roofs and pavements to decrease the surface temperature in cities and reduce the release of the sensible heat that contributes to increase the urban ambient temperature. Hundreds of large scale real implementations of advanced mitigation materials in cities have demonstrated that it is feasible to decrease the peak urban ambient temperatures up to 2.5–3 C. It is expected that the development and implementation of advanced photonic materials in cities may enhance the mitigation potential up to 4.0–5.5°.

It is well accepted that the nest possible policy to eradicate energy poverty and protect the well being of vulnerable population, is associated to the energy retrofitting of low income dwellings. All large scale retrofitting projects addressing the low income population in Europe has concluded that there are very serious financial, social and environmental advantages for the vulnerable households. Full understanding of the necessary technical characteristics of the retrofitted low income houses and assessment of the cost and benefits, are necessary conditions to design and implement an efficient program to eradicate the energy poverty problem in Europe.

Energy poverty, excessive energy consumption of buildings, and the regional climate change and urban overheating are among the most significant problems associated to the built environment in Europe. It is important to be understood that the above three problems are strongly interrelated characterized by very serious trade offs and synergies. Thus policies addressing the problems of energy consumption, regional climate change and energy poverty should be designed in an integrated and holistic way to address in parallel the three problem as a common issue. If not its is inevitable to face a continuous degradation of the thermal conditions in our cities, a new increase of the energy consumption for buildings and a surge of the energy poverty in Europe, while economic and social discrepancies may rise as well.

The objective of Innovating to zero the built environment in Europe is an ambitious target that aims to eradicate energy poverty, minimize the energy consumption of buildings and mitigate as much as possible urban overheating and regional climate change.

It is well accepted that a minimization to zero is an unequivocal objective that will generate considerable new opportunities for growth and development.