> 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/workflows/daylight/daylight-info/bess/winter-sunlight.md).

# Winter Sunlight

BESS Winter Sunlight criteria for multi-unit developments (apartments, aged care, hotels) aims to enhance amenities and reduce heating needs. Points are allocated as per the following requirements.

> *"Points are awarded where at least 70% of dwellings receive at least 3 hours of direct sunlight in all Living areas between 9 am and 3 pm in mid-winter. This can be demonstrated on plans or by modelling (in conjunction with daylight modelling)."*

### What is Direct Sunlight in BESS

Within BESS, 'Direct Sunlight' is defined as:

> *"Unobstructed sunlight that penetrates the living room space by at least 1 meter at any time during the day"*

In direct terms for BESS, 'Direct Sunlight' refers to the illumination received directly from the sun between 9 am and 3 pm on the winter equinox (June 21st) into the Living Areas by at least 1 meter from the internal finishes for 3 hours of the day.

{% hint style="info" %}
The winter solstice is the day of the year with the least daylight hours of any in the year and usually occurs on 22 June but can occur between 21 and 23 June.
{% endhint %}

<img src="/files/Sbie0mxpm9pn3LP6tHie" alt="" class="gitbook-drawing">

### Modelling Winter Sunlight in Speckel

To meet Winter Sunlight's requirements, the Space's Purpose must be defined within the model for that Space to be selected for assessment. In this case, the 'Living Spaces' must be defined with a [Purpose](broken://pages/dVGTIfnbNp9Pm2bQvXbl). Once defined, the [Daylight form](https://support-and-docs.gitbook.io/speckel-docs/user-manual/building/simulation/daylight) is used to nominate the [Metric](broken://pages/vLwTpQcI3D3mRAeAW7QT), [Grid](broken://pages/ZmDyt32so5DHQ4fHrKZm), [Surface](broken://pages/yhjFsYcMrvvbRRTuDHBx) and [Simulation Settings ](broken://pages/H2o1xCL2NAseSjcTacNB)before running a simulation. For the Metric, an [Annual Sunlight Exposure (ASE)](https://support-and-docs.gitbook.io/speckel-docs/user-manual/building/simulation/daylight/metrics#annual-sunlight-exposure) metric must be configured as per the requirements of Winter Sunlight, where at least 70% of dwellings receive at least 3 hours of direct sunlight in all Living areas between 9 am and 3 pm in mid-winter. Midwinter is assumed to be the winter equinox (June 21st).

<figure><img src="/files/E1ooazQZl8EAZGT6o9Gx" alt=""><figcaption></figcaption></figure>

## Outputs on Speckel

Once a Winter Sunlight simulation has been undertaken, results are available in your browser and a report detailing assumptions used and results achieved.

{% hint style="success" %}
Looking for a quick tutorial? Check out [BESS Daylight Access](/support-and-training/other-support/tutorials/speckel-tutorial-archive/bess-daylight-access.md).
{% endhint %}


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