## 3 Proposed Workflow for the Tool Design  
With the aim of evaluating the functional accessibility of circulation areas in universally accessible housing (UAH), an immersive virtual reality experience was developed, structured into five methodological stages. Figure 2 illustrates the proposed workflow for the development of an evaluation tool for universally accessible housing design in virtual reality environments. The process comprises five stages, ranging from the definition of the type of housing and the relevant regulatory and ergonomic parameters, to the implementation of an interactive virtual environment that simulates everyday situations from the perspective of a wheelchair user. The proposed approach combines the use of BIM models, realistic environmental rendering, movement and interaction programming through Blueprints in Unreal Engine, and the integration of automated measurement systems to  
Figure 1: Research methodology. record collisions, time spent in specific areas, and user interactions during the experience. While the tool is based on Chilean regulations [21] its analysis and applications are extensible to other international standards. It enables the creation of a controlled, realistic, and functional environment aimed at assessing accessible design under virtual conditions prior to construction, incorporating key elements for spatial performance analysis and facilitating the identification of accessibility barriers. The following section describes each stage of the proposed workflow. * Stage 1--Type of Housing and Parameters of Interest. This stage serves as the starting point of the process. The type of housing to be used is defined, along with the specific areas to be evaluated, focusing on interior access and circulation spaces. A set of parameters aimed at ensuring accessibility in these areas is identified, which must be analyzed based on current regulations and ergonomic criteria. This analysis considers the maneuvers a wheelchair user can perform within the home, as well as the everyday situations they may encounter in their daily life. * Stage 2--Creation of the Immersive Environment. In this phase, the process begins with a BIM model (multi-parameter 3D model) of a previously designed accessible home. This model is exported in.FBX format for integration into the virtual reality development engine, Unreal Engine. Once integrated, the environment is enriched  
Figure 2: Proposed workflow for the tool design. with complementary elements to enhance realism, such as neighboring houses, sky, vegetation, lighting, and everyday objects like switches and doors. This environmental design aims to increase user immersion by adapting the virtual setting to an urban or rural context, depending on the housing location. * Stage 3--Design of Controls, Movements, and Collisions. This stage involves the design of the user's movement and interaction logic within the virtual environment. The experience begins with the user seated in a virtual wheelchair, with leg movements disabled to maintain consistency with the represented avatar. No visible virtual character is included to avoid the perception of \"another\"; instead, only synthetic hands are used, positioned where the VR headset controllers are gripped. A conceptual interaction model (hands, wheelchair, and camera) is defined, establishing possible movements guided by the wheelchair, which acts as the pivot for first-person navigation. The virtual wheelchair's dimensions were modeled to approximate standard adult manual wheelchair sizes, referencing common anthropometric data and the maneuvering space requirements (e.g., an approximate width of 70 cm and a length ensuring a 1.5 m turning diameter).