Greening the Built Environment: Maintenance, Rehabilitation, and Energy Maximum Utilization in Existing Buildings

Dear Colleagues,

In 40 years, more than 90% of the built environment in the EU will consist of buildings already in use today. The turnover of building stock is very slow; therefore, improving the environmental performance of existing buildings is the main challenge that we must face immediately and quickly. Adequate maintenance and rehabilitation, as well as the correct valorization of both the energy and the resources that this stock already embeds, are the only possible ways to improve sustainability as a whole and to meet the increasingly stringent requirements that buildings will have to assure.

The path towards greener buildings has been undertaken in recent decades almost all over the world, showing that this industrial transformation can strongly contribute to climate change mitigation, playing a crucial role in the transition to a more sustainable environment. However, most of the efforts are devoted to the construction of new high-performance green buildings, which represent and will continue to be, a small share of the entire stock in service. Furthermore, this strategy is still mainly aimed at minimizing the impact generated in the operational phase of the entire life cycle of a building; however, conclusive evidence is often not provided with respect to the effects on the environmental balance of the entire process.

As “the greenest building is the one that is already built”, its refurbishment according to environmental sustainability principles is estimated to achieve energy savings of 23% in the construction phase compared with new construction, whereas an energy-efficient new building will take at least 65 years to recover the energy and resources lost through its demolition, even when 40% of the demolished materials are recycled.

• Deeper comprehension is thus needed to determine how an effective environmental balance could be drafted by properly considering the entire building life cycle and the impacts affecting its diverse stages.

On the other hand, the decision between refurbishing or demolishing and rebuilding involves a very complex assessment, due to the many elements involved and the multiple different implications that each scenario triggers. Among others are included those related to the technical feasibility of retrofitting and its effectiveness, economic concerns, environmental issues, and the need for preserving social and cultural heritage elements.

Supporting the decision on a comprehensive and balanced evaluation scheme is especially hard when the gap is very large between the levels of performance required for the future use of the building and those that it is currently capable of providing.

• More effective assessment methods and tools are needed to drive the intervention strategies, as well as a larger set of study cases helping in identifying gauging the whole range of variables involved.

Compatible new uses and appropriate, feasible design solutions must be defined to make existing buildings valuable resources. Carbon emissions from energy use fell by 6.3%, to their lowest level since 2011, and the global energy demand was estimated to have fallen by 4.5% in 2020. Bernard Looney states that “The challenge is to achieve sustained, comparable year-on-year reductions in emissions without massive disruption to our livelihoods and our everyday lives”. Hence, rehabilitation projects must optimize the maximum energy use: (1) in the materials already incorporated into buildings; (2) in the performance of the building envelope to reduce energy losses and optimize thermal efficiency; (3) in relation to the new uses of existing buildings; and (4) from renewable sources, to contribute to improving the overall environmental sustainability of existing buildings while steering the design of new constructions.

This Special Issue calls for processes and techniques suitable to exploit most of the remaining performance as well as to maximize energy utilization both at the whole building and component and material scales, as well as to remove the regulatory barriers and define a coherent framework of technical standards that support these practices.

Although many technologies, solutions, and design approaches are currently available that relate to achieving this goal, the scientific knowledge on the topic must be enhanced by the outcomes of further lab and in-field tests, real-scale applications of measurable effectiveness, and comparative analyses of cases. This, in particular, concerns:

- Design methods and strategies, climate change mitigation by design, sustainable design approaches;

- Construction and demolition waste reduction, assessment, and suitable exploitation of the residual technical performances of salvaged building components;

- Combined environmental and economic sustainability assessment of building refurbishment processes;

- Metrics, protocols, indicators, and rating tools;

- Effective maintenance strategies, durability enhancement, and lifespan extension of building materials and components;

- Techniques and tools for selective dismantling, treatments for increasing the reusability of salvaged materials, new/adapted technical regulations, and standards for salvaged building material components.

Contributions aiming to discover and highlight these future scenarios are welcome.

Prof. Dr. Antonello Monsù Scolaro
Prof. Dr. Ernesto Antonini
Prof. Dr. Stefania de Medici 
Guest Editors

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• climate change mitigation
• combined sustainable design in building refurbishment
• retrofitting design to energy maximum utilization in building refurbishment
• maximum renewable energy utilization
• maximum energy utilization and new use of existing buildings
• maximum energy utilization in efficient envelops
• C&amp
• D waste reduction and valorisation
• embodied energy reuse in building materials
• effective maintenance strategies
• lifespan extension of existing building materials and components
• selective dismantling (techniques and tools)
• system rating tools of green buildings