> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/user-guide/2d-building/envelope/opaque-doors.md). # Opaque Doors An opaque door is part of the building envelope separating conditioned and unconditioned spaces. It does not allow light to penetrate but can still significantly impact heat transfer between spaces. ### Specify an Opaque Door Opaque Doors (typically hinged) can be added to any aspect to be considered in energy or daylight modelling. They are generally lightweight and have little to no thermal performance. Add Opaque Doors by selecting the aspect and then select ‘Select Opaque Door’ on the Envelope tab and either 'As Concept' or 'As Default'. Specify the Opaque Door 'Total R-value', 'Solar Absorbtance', 'Thickness', 'Density' and 'Heat Capacity', as required, and then click 'Save'.

--- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.betterbuilding.io/user-guide/2d-building/envelope/opaque-doors.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.