PVC or aluminium windows for a Costa Blanca home?

Neither is better in every situation. PVC insulates well and suits conventional bedroom and living-room openings. Aluminium is stronger, so it holds larger spans and sliding doors with slimmer frames. The right answer usually varies between rooms in the same house.

Untreated aluminium conducts heat readily. A thermally broken system separates the inside and outside of the frame so that heat transfer is reduced. If aluminium is being considered for a sun-facing elevation, the thermal break matters more than the frame material itself.

PVC profiles are wider and need steel reinforcement as spans increase. That is workable up to a point, but on wide terrace openings aluminium usually gives a better result with less frame and more glass.

Modern PVC is UV-stabilised and holds its colour far better than older generations. Darker foils absorb more heat than white and behave differently on exposed south and west elevations, which is worth raising before choosing a finish.

Compare the complete specification rather than the frame material. Check the glass build-up, whether the aluminium is thermally broken, the hardware brand, the reinforcement in the PVC, and what the installation includes. A well-specified frame in either material beats a poorly specified one in the other.