# Skylights

A skylight is a part of the building envelope and is a window-like element placed on the roof of a building to allow natural light to enter the space from above. 

Skylights can be added to any roof surface to be considered in energy or daylight modelling. Where compliance calculations are being undertaken, the Reference Building skylight is nominated as per the local Building Code. See [Add Skylights](/user-guide/2d-building/building/levels/roof-geometry/add-skylights.md) for more information on drawing and geometry. 

### Specify a Skylight

To specify a skylight, navigate to the 'Envelope' settings in the left panel and select 'Skylights'. Next, set the 'System U-value' or 'System R-value', as locally applicable, the System SHGC and VLT and hit 'Save'. You can also use 'Tags' to nominate different specifications if more than one skylight specification is within the design.

<figure><img src="/files/uQvkFMzxi5Zfg5hzLcuq" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/UFz8B21lhlEHhw4R8TIi" alt=""><figcaption></figcaption></figure>


---

# Agent Instructions: 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:

```
GET https://docs.betterbuilding.io/user-guide/2d-building/envelope/skylights.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.