# Construction System

<figure><img src="https://2857854828-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FZMJFAAAzlru9sJQzKb8X%2Fuploads%2F9v4KiXt6rEJj1yknorbv%2FDigram%2002.png?alt=media&#x26;token=6ffee291-3589-4584-b79f-6c130aa6bc79" alt=""><figcaption></figcaption></figure>

#### A building's construction system is responsible for supplying building NFTs to the ecosystem. To upgrade a building's tier, buildings of the same tier are used as materials (=demand). The number of buildings is reduced by the upgrading system, and the construction system is there to supply them again. However, only building owners (who are granted a construction license per building) can build new buildings, and Lay 007 Robot and $Orb are consumed as resources to construct new buildings.

{% hint style="danger" %} <mark style="color:red;">**Note: Keep in mind that all tokens and NFTs spent on the upgrade are irrevocable and non-refundable.**</mark>
{% endhint %}