Parametric BIM-based life cycle assessment framework for optimal sustainable design

Highlights

• The assessment analyzes the building materials efficiency using visual programming.

• The resulting emissions are optimized using NSGA-II for decision-making processes.

• The buildings are evaluated through LCA and DEA for the optimum material selection.

• The proposed LCA adapts the existing BIM concepts with the circularity principles.

• The proposed parametric framework achieved a flexible LCA using BIM.

Abstract

The construction sector is liable for a sizable amount of CO₂ emissions and waste. Life Cycle Assessment (LCA) is considered one of the crucial tools that aids in evaluating the impacts of construction emissions. This research aims to quantify the life cycle impacts of the initial and recurrent embodied emissions, operating and reuse/disposal emissions, and utilizing Building Information Modeling (BIM) for a more holistic life cycle approach. The research proposes a parametric BIM-based LCA framework for quantifying the environmental impacts and evaluating the effects of material selection for both embodied and operating emissions. In addition, it considers the different reuse scenarios and percentages and their effect on both the embodied and operating impacts. The proposed framework consists of five main modules: data acquisition module, operating and embodied emissions module, life cycle assessment module, optimization module, and decision-making module. This parametric assessment can be applied for both the conventional and circular approach impacts. For the decision-making process, the resulting emissions are optimized utilizing the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and evaluated through an LCA and Data Envelopment Analysis (DEA) methodology for the material selection. A case study of a residential villa in Cairo is worked out to illustrate the key features of the proposed framework. This assessment analyzes the building materials’ characteristics and efficiency investigating the external walls, internal walls, floors, roofs, and windows design possibilities, and uses visual programming to control the resulting emissions for a more flexible approach. By comparing the integrated LCA and DEA models three optimum design solutions, the conventional approach develops design solutions of higher embodied Global Warming Potential (GWP) than the circular approach. However, it develops lower operating GWP with better applied U-values. The circularity approach employment has reduced the efficiency of the operating GWP due to utilizing materials with high heat transmittance ability.

Introduction

The construction industry consumes the most significant commercial energy through electricity and heat usage by directly burning fossil fuels [1], leading to increased carbon emissions, one of the causes of climate change and global warming problems [2]. As per Ibn-Mohamed et al. [3], global warming is one of the most severe global sustainability issues produced by operating and embodied global energy emissions. However, the embodied CO₂ emissions are neglected for having smaller emissions magnitude, and more significant efforts are employed to reduce operating emissions. However, the building’s embodied energy and life cycle energy will increase significantly by applying the operational energy usage reduction measures alone without considering the embodied energy [4].

The Sustainable Development Goals (SDGs) are employed to reduce these CO₂ emissions to net-zero by 2050 to lower climate change and its impacts by restricting the temperature expansion by 1.5 °C on average [2]. This goal is achieved through the SDG 13 for the climate action, as the energy CO₂ emissions has increased by 6% in 2021 [5]. SDGs are also employed to reduce the material footprint for sustainable consumption and production processes, through the SDG 11 for sustainable cities and communities [5]. According to the International Organization for Standardization through ISO:14044 [6] guidelines and requirements, the life cycle assessment model acts as a tool for achieving some of these SDGs. The life cycle assessment will assist in the trade-off determination for better mitigation efforts and decision-making. It is utilized for efficient building design through the material selection of lower embodied emissions [3]. According to Alwan et al. [7], the whole life cycle perspective is not accounted for, as the embodied energy assessment processes are complex and time-consuming compared to the operating energy assessment. Another challenge hindering the quantification of the embodied carbon emissions estimation is the varying accuracy of the obtained results [3], restricting its usage in the decision-making process. Accordingly, life cycle assessment analysis needs to be deployed in the current digitalization effort of buildings instead of the current manual calculations, using Building Information Modeling (BIM).

The usage of virgin materials in each life cycle of the building makes the construction and demolition industry responsible for about 50% of the consumption of virgin raw materials and 40% of the total solid waste production [8]. Therefore, a system for reusing the building materials for subsequent production cycles needs to be introduced to extend the useful life of products for waste reduction and maintain materials and resources as long as possible in the economic system [8]. The life cycle assessment has different approaches; the first is the study of the environmental impacts of the stages from the raw material extraction to the factory gate, known as cradle-to-gate. The second one is the study of the whole life cycle of the building and products known as cradle-to-grave in the traditional approaches of linear products. The third one is transforming the cradle-to-grave to cradle-to-cradle (C2C) for the closed economy approach [8].

This research aims to develop a flexible life cycle assessment framework in the early design stage with a high level of detail (LOD) for more sustainable residential buildings by quantifying and determining the Global Warming Potential (GWP). Furthermore, the parametric life cycle assessment tool supports construction designers by deriving the needed sustainability data for sustainably evaluating residential buildings by measuring the CO₂ equivalent emissions for each design scenario produced for conventional (cradle-to-grave) and circular (C2C) approaches. The parametric framework is an interactive user-led framework for instant identification of energy and environmental impacts in critical stages. Besides, creating a decision-making tool that aids in performing Life Cycle Assessment (LCA) using Data Envelopment Analysis (DEA) model, developing the optimal design solution with optimal materials using the Pareto front solutions. The developed parametric BIM-based framework can be employed on various types of buildings such as midrise apartments, warehouses, and offices. This is accomplished utilizing the different Honeybee (HB) [9] plug-in building programs. These buildings have known characteristics about the location, building elements’ area and volume, rooms distribution for thermal loads, materials used and their R-values and U-values, and the assumptions regarding the reused and wasted materials.