To　address　the　challenge　of　modelling　intricate　crack　patterns　in　brittle　materials,　this　study　introduces　a　novel　damage　framework　with　thermo-mechanical　coupling.　By　integrating　thermal　effects　within　a　unified　energy　variational　framework,　the　model　incorporates　an　innovative　damage　variable　that　explicitly　accounts　for　thermal　deformation　and　accurately　characterises　the　topology　of　thermal　cracks.　The　explicit　thermo-damage　variable　and　governing　equations　are　directly　derived　from　the　variational　functional,　enabling　efficient　resolution　of　thermal　fracture　problems　by　focusing　solely　on　displacement　and　temperature　fields.　Furthermore,　the　proposed　framework　demonstrates　the　potential　for　extension　to　other　multi-field　coupled　fracture　problems　driven　by　environmentally　induced　strain.　A　series　of　simulations,　including　purely　mechanical　as　well　as　2D　and　3D　thermo-mechanical　scenarios,　validate　the　model＇s　capability　to　effectively　capture　intricate　crack　behaviours.