There are a wide range of gas detection strategies applied in the hazardous industries, all with varying strengths and limitations. With the increasing commercialisation of 'gas detection mapping', more and more innovative methods are appearing, all with the promise of saving money in the process. But can there be one gas detection methodology to rule them all? This paper reviews the impact the type of facility has on the strengths and limitations of each methodology in such an application. The paper applies a case study which focuses on an internal building, and compares the two most robust methodologies for design: Target gas cloud detection and computational fluid dynamics in the generation of gas detector layouts. This analysis is currently being used as an input to the ISA guidance document TR84.00.07 Guidance on the Evaluation of Fire and Gas System Effectiveness. Other methods of gas detection design shall be explored such as scenario based modelling, and facilities such as open onshore petrochemical sites, and partially enclosed offshore platforms, while analysing the strengths and limitations of each methodology against the given facility. One area of discussion surrounds the repeatability of design, to ensure ease of audit and repeatability across other similar assets, while addressing the risk of a design becoming too prescriptive and not subsequently suited to the hazards of a specific application. The paper will also review the common misconceptions of both CFD modelling and target gas cloud design philosophies, which can often lead to over/under engineered designs and reduce overall confidence in the field of gas detection design. The ultimate finding of the research proves that regardless of the methodology applied, engineering competence should be at the forefront of application. It is crucial that the incorporation of adequately educated safety professionals at an appropriately early stage, to ensure a safe design from the front end of a project. (C) 2017 Elsevier Ltd. All rights reserved.