Upgrade

Several buildings, including your Headquarters, Training Facility, and Assembly Plant, can be upgraded. Upgrading buildings unlocks prerequisites and advances you along the technology tree. Also, upgraded buildings generally have higher health and thus can survive better against assault.

To upgrade a structure, select it and press the “Upgrade” button found on the Build Menu. Alternately, select the building and press u.

Certain units and structures require upgraded buildings in order to be constructed. Furthermore, in order to perform upgrades, you need to meet certain requirements. You can select a building and point the mouse at the “Upgrade” button to see the requirements for performing an upgrade.

Upgrades are not available in certain campaign missions. If the technology level of the mission is not high enough, you will be unable to upgrade your buildings even if you meet all of the other prerequisites.

Upgrades cost credits and require some amount of time. You can see a progress bar on an upgrading building just as if it was under construction. A building that is in the process of being upgraded cannot train units. Also note that upgraded versions of buildings can use more power than the lesser version, so make sure you have enough power to support your newly-upgraded building before you begin the upgrade.