Abstract. Adaptive reuse is an important strategy for achieving sustainability as it ensures a continuous building life cycle and prevents building destruction. Adaptive reuse has the greatest potential to lower the environmental load of the built environment significantly within the next 20 to 30 years. But, the owners and practitioners still lack of point of references to justify and evaluate their decision making with regard to the adaptation practice. The aim of this paper is to explore the unique criteria of decision making among practitioners in the application of adaptive reuse of existing buildings. The descriptive study has identified five main criteria influenced in decision making in adaptive reuse that effected to the sustainable development; economic, environment, social, legislative and architecture. We designed a questionnaire to determine the most significant criteria in decision making for adaptive reuse towards sustainable development among practitioners. The paper describes the process in identifying the unique criteria and the proposed methodology for the study.

Purpose Within the next 20–30 years, adaptive reuse will have the greatest potential to reduce the built environment's environmental impact. Despite this, stakeholders still do not have sufficient points of reference in justifying and evaluating their adaptation practice decisions. The decision to reuse a building involves a complex set of considerations, including economic, social, environmental, legislative and architectural issues. The purpose of this paper is to investigate the unique decision-making criteria among stakeholders when considering adaptive reuse of an existing building asset in Malaysian heritage cities. Design/Methodology/Approach Thirty (30) unique criteria of decision-making were identified through a detailed literature review. The quantitative method of a self-completion questionnaire survey was conducted among stakeholders, including architects, valuers, planners, government department, developers and building owners. There were asked about their opinion and view on the criteria that could have influenced the decision-making in considering the adaptive reuse of the existing buildings in two heritage cities in the states of Penang and Malacca, Malaysia. Thus, it is the aim of this paper to evaluate and reveal the key criteria pertaining to this. Findings The analysis shows that there are seven key criteria that influence the decision-making of adaptive reuse of existing building: building value; building suitability; structural condition; official plan and zoning; building code; client requirement and heritage designated. In this regard, while “building value” factors were the key determinants in deciding whether to reuse or demolish, the asset’s suitability and structural condition, as well as rules, were also taken into account. Additionally, the environmental, economic and social tenets of sustainability were also identified as important, but were given less weight in matters concerning reuse. And due to the fact that many of the existing buildings are rapidly becoming obsolete, they are now increasingly being prioritized during the adaptive reuse decision-making process to ensure long-term outcomes. Research Limitations/Implications The research is limited owing to the difficulty in obtaining accurate information concerning the number of decision agents who have been involved in the adaptive reuse of existing buildings. Thus, the respondents in this research were randomly selected. Due to this limitation, the result does not encompass the whole Malaysia, only the stakeholders in Penang and Malacca have been selected the respondents in this study as these states are listed in the UNESCO World Heritage. Social Implications When deciding whether to reuse or demolish an existing building, the proposed criteria will outline the crucial areas that must be examined by owners, developers and key project stakeholders. It can also be used to assess the financial, physical and social aspects of a cultural project. Originality/Value This paper adds to the body of knowledge concerning decision-making criteria for adaptive reuse strategies in achieving heritage city sustainability.