A Sustainable Framework for the Optimization of Retrofit Strategies of Existing Buildings

The construction industry is one of the major causes of both the consumption of natural resources and environmental pollution. Buildings have a significant environmental impact during their life-cycle, consuming huge amounts of energy and natural assets and affecting the air and water quality in our cities. The life-cycle of a building consists of two phases: design and facility management (FM). Raw materials such as steel, concrete, iron, wood and brick are used in the first stage, while natural resources like water, natural gas and energy are utilized throughout the entire life-cycle. In addition, environmental effects include an increase in greenhouse gas emissions, global warming and the depletion of the ozone layer. Several negative effects on the environment are also the consequence of deconstruction activities due to the intensive use of natural assets and the generation of solid and liquid waste. As a consequence, all the stakeholders involved in the Architecture Engineering Construction (AEC) sector, such as architects, engineers, energy consultants, project managers, building users and local administrators, are working together to develop appropriate technologies. Indeed, the rising cost of energy, the overconsumption of natural resources, and all the environmental issues mentioned above have led to an increased demand for sustainable building structures with a low environmental impact, following eco-friendly principles. This means that the construction sector is in a period where there is a need for two important elements. The first is a boost in terms of eco-efficiency, which is considered to be an integration of several environmental and economic aspects aimed at reducing waste and the use of resources, as well as the ecological impact. The second is the development of innovative and digital methodologies that are able to ensure coordination between stakeholders, with the aim being to achieve the cultural and social-economic sustainability of a building. As a result, the role of sustainable design has assumed fundamental importance. The concept of sustainability associated with the construction industry provides an opportunity to create facilities with the same functionalities as those designed with a traditional approach, but with a low environmental impact and high energy efficiency. The concept of sustainable building needs to be implemented in all the phases of a building’s life-cycle, from design to construction (including the consumption of raw materials and natural resources), and from the usage phase to the deconstruction of the building (including the management of solid and liquid waste). A sustainable development model is based on three key concepts: good environmental management; social responsibility and cost-saving solutions. Consequently, it may be said that sustainability has three main components: environmental; economic; and social. Within this context, demands made on the construction industry are moving in the direction of a transformation which is both rapid and radical (from a digital point of view), with the purpose being to place the management of the information flow at the centre of this “revolution” in order to increase the effectiveness of decision-making and sustainable design. Over the last decade, there has been growing interest within the construction sector in using Building Information Models (BIMs), due to their numerous benefits and resource savings during the design, planning, construction and management stages of buildings. A Building Information Model is a digital representation of the physical and functional characteristics of a facility and its related life-cycle information. The resulting model is a data rich, object-oriented, intelligent and parametric digital representation of a building, and serves as a shared repository of information for building owners and operators during its life-cycle. A BIM represents the shared resource of information that provides a reliable basis for decision-making from the design stage to deconstruction and throughout the building’s life-cycle. The BIM tool allows various types of information to be managed, such as the planning of resources, energy analyses, cost assessments and time schedules. This multi-disciplinary information can be synthesized within one model. A BIM system is a central scheme that involves different stakeholders at different phases of the life-cycle of a facility, enabling information in the BIM model to be inserted, extracted, updated or modified. This collaborative approach enables a focus on the design process of a building on environmental and economic issues, such as construction and maintenance costs and energy efficiency. Building Information Models are a way of producing sustainable models and conducting performance analyses throughout a building’s life-cycle. This is why BIM models are increasingly being used to support sustainable designs, construction, operations and the demolition of buildings. The BIM digital revolution will affect the entire construction industry, providing several benefits and generating buildings that operate more efficiently. It is important to note that the digital models produced also aim to mitigate risks (such as seismic risks), as well as increase efficiency and effectiveness. What is more, the “BIM-oriented” planning of buildings has extraordinary advantages: increased productivity, fewer errors, less downtime, lower costs, greater inter-operability and the maximum sharing of information. Refurbishment is carried out to improve the performance of a building and, sometimes, to meet the requirements of owners and building codes. These renovation measures include structural upgrades such as seismic and energy retrofits like improving electrical or plumbing systems or thermal insulation. These operations require a great deal of data about structural and non-structural components, as well as their materials and compositions, geometry and physical properties. Integration with BIM methodologies is fundamental to this phase of the life-cycle, because they are able to manage large amounts of data and improve the feasibility of the processes. By exploring the relationship between BIMs and sustainability in the construction industry, the aim of this thesis is to demonstrate how sustainable design principles that focus on structural retrofits and the renovation of existing buildings may be implemented with the support of BIM methodologies. The approach of this research moves from the consideration that the management of the structural design process has a significant impact on the management of the sustainability of an entire building. A weakness in the performance of a structural system may affect the functionalities of building components, and this may in turn produce a weakness in the functionality of the whole system. This research develops different applications of an integrated platform, where information converges from energy, economic and environmental elements. The final aim of this sustainable framework is to support researchers, designers and practitioners in the decision-making stage, thereby optimizing environmental aspects, structural retrofit strategies and energy retrofit solutions during the life-cycle of buildings that are prone to seismic risk. Chapter 1 of this thesis contains a brief introduction to Building Information Modelling. It describes the advantages of a BIM-oriented design and the maturity levels of the methodology, and also investigates the application of BIMs in the life-cycle of buildings. Chapter 2 sets out a procedure to assess the environmental impact of some seismic retrofit interventions on an existing reinforced concrete (RC) building. Once the structural requirements have been satisfied and the environmental effects of these retrofit solutions defined, the final aim is to identify the most environmentally sustainable retrofit strategy. The environmental impact of the structural retrofit options is assessed using a life-cycle assessment (LCA). In Chapter 3, a simplified method based on a semi-probabilistic methodology is developed to evaluate the economic performance of a building prone to seismic risk. The proposed approach aims to identify the most cost-effective strengthening strategies and levels for existing structures during their structural lifetime. To this end, the method identifies: the optimal strengthening level, computing the costs of strengthening the structure at different performance levels for each strategy; and the expected seismic loss during its lifetime. Chapter 4 develops the BIM-based approach to support the engineering analysis of RC structures and manage the large amount of data required for a detailed seismic analysis. In particular, a BIM is used in an economic seismic loss assessment procedure in order to improve the feasibility of the process and the accuracy of the analysis. The framework developed is able to assess the expected seismic and economic losses of an existing building and to optimize retrofit operations from an economic point of view. Chapter 5 introduces a sustainability assessment framework for the retrofit process of existing buildings based on the integration of energy and structural aspects. Multi-stage energy optimization is carried out by implementing a genetic algorithm and a smart research strategy. As a consequence, cost-optimal energy retrofit solutions are identified and their influence on the expected economic losses due to seismic damage is assessed throughout a building’s lifetime. Chapter 6 sets out the methodological framework, which enables us to address the integration of the seismic and energy retrofitting of existing buildings from an economic point of view. The overall outcome of this integration is handled in terms of the global expected cost, which includes the economic indicators associated with adopted energy measures and economic loss quantifications related to the structural performance of the retrofitted building

Designing low carbon buildings : a framework to reduce energy consumption and embed the use of renewables

EU policies to mitigate climate change set ambitious goals for energy and carbon reduction for the built environment. In order meet and even exceed the EU targets the UK Government's Climate Change Act 2008 sets a target to reduce greenhouse gas emissions in the UK by at least 80% from 1990 levels by 2050. To support these targets the UK government also aims to ensure that 20% of the UK's electricity is supplied from renewable sources by 2020. This article presents a design framework and a set of integrated IT tools to enable an analysis of the energy performance of building designs, including consideration of active and passive renewable energy technologies, when the opportunity to substantially improve the whole life-cycle energy performance of those designs is still open. To ensure a good fit with current architectural practices the design framework is integrated with the Royal Institute of British Architects (RIBA) key stages, which is the most widely used framework for the delivery of construction projects. The main aims of this article are to illustrate the need for new approaches to support low carbon building design that can be integrated into current architectural practice, to present the design framework developed in this research and illustrate its application in a case study

Life-cycle assessment of buildings: a Review

Life-Cycle Assessment (LCA) is one of various management tools for evaluating environmental concerns. This paper reviews LCA from a buildings perspective. It highlights the need for its use within the building sector, and the importance of LCA as a decision making support tool. It discusses LCA methodologies and applications within the building sector, reviewing some of the life-cycle studies applied to buildings or building materials and component combinations within the last fifteen years in Europe and the United States. It highlights the problems of a lack of an internationally comparable and agreed data inventory and assessment methodology which hinder the application of LCA within the building industry. It identifies key areas for future research as (i) the whole process of construction, (ii) the relative weighting of different environmental impacts and (iii) applications in developing countries

Assessment of CO2 emissions reduction in a distribution warehouse

Building energy use accounts for almost 50% of the total CO2 emissions in the UK. Most of the research has focused on reducing the operational impact of buildings, however in recent years many studies have indicated the significance of embodied energy in different building types. This paper primarily focuses on illustrating the relative importance of operational and embodied energy in a flexible use light distribution warehouse. The building is chosen for the study as it is relatively easy to model and represents many distribution centres and industrial warehouses in Europe. A carbon footprinting study was carried out by conducting an inventory of the major installed materials with potentially significant carbon impact and material substitutions covering the building structure. Ecotect computer simulation program was used to determine the energy consumption for the 25 years design life of the building. This paper evaluates alternative design strategies for the envelope of the building and their effects on the whole life emissions by investigating both embodied and operational implications of changing the envelope characteristics. The results provide an insight to quantify the total amount of CO2 emissions saved through design optimisation by modelling embodied and operational energy

A Decision Making System for Selecting Sustainable Technologies for Retail Buildings

CIB Publication 382: Selected papers presented at the CIB World Building Congres Construction and Society, Brisbane 5-9 May 2013 Papers from the Designated Session TG66 - Energy and the Built EnvironmentThe implementation of sustainable technologies can improve the energy and carbon efficiency of existing retail buildings. However, the selection of an appropriate sustainable technology is a complex task due to the large number of technological alternatives and decision criteria that need to be considered. Also, there exist series of uncertainties that are associated with the use of sustainable technologies, but have to be evaluated to achieve realistic and transparent results. The selection of sustainable technology is therefore most challenging. An earlier study was conducted with UK experienced practitioners including clients/developers, engineers, contractors and suppliers to identify the drivers and barriers for the use of sustainable technologies in UK retail construction. One major barrier identified from the study was the lack of a decision making tool, highlighted by both construction professionals and stakeholders in the retail industry. The large number of alternatives and potential solutions require a decision support method to be implemented. Information data on the economic variables, energy performance and impact on the environment of these systems is presently affected by vagueness and lack of knowledge. To deal with this high level of complexity and uncertainty an evaluation support approach is needed. This paper aims to develop a decision making framework to assist both retailers and construction professionals to define and evaluate the selection of sustainable technological options for delivering retail buildings. The research was carried out through a combination of a critical literature review and a survey-based study using expert opinions of retailers and contractors. The developed framework of decision criteria should provide a sustainable technology model to assist both construction professionals and stakeholders in the retail industry to systematically and effectively select the most appropriate technology. This approach should make the decision progression more transparent and facilitate sustainable development of retail buildings in achieving the carbon targets set by the UK and other governments

Making asset investment decisions for wastewater systems that include sustainability

Effective integrated water management is a key component of the World Water Vision and the way in which aspirations for water equity may be realized. Part of the vision includes the promotion of sustainability of water systems and full accountability for their interaction with other urban systems. One major problem is that “sustainability” remains an elusive concept, although those involved with the provision of urban wastewater systems now recognize that decisions involving asset investment should use the “triple bottom line” approach to society, the economy, and the environment. The Sustainable Water Industry Asset Resource Decisions project has devised a flexible and adaptable framework of decision support processes that can be used to include the principles of sustainability more effectively. Decision mapping conducted at the outset of the project has shown that only a narrow range of criteria currently influence the outcome of asset investment decisions. This paper addresses the concepts of sustainability assessment and presents two case studies that illustrate how multicriteria decision support systems can enhance the assessment of the relative sustainability of a range of options when decisions are being made about wastewater asset investment