Tunable white sounds like a feature until you have to write it into a spec. "2700K–5000K" is a range, not a setting, and the difference between a fixture that dims warm and one that shifts warm is the difference between a happy client and a callback.
What the range actually means
A tunable-white fixture carries two or more LED channels — typically a warm 2700K array and a cool 5000K array — and mixes them. The CCT you get is the mix ratio, not a filter. That has two consequences worth putting in the submittal:
CRI can shift across the range. A fixture claiming 90 CRI at 3000K may measure 85 at 5000K. Ask for the LM-79 at both ends, not the midpoint.
Delivered lumens usually drop as you warm up. A 4000K-rated fixture at 2700K is often 10–15% dimmer.
When it is worth specifying
Tunable white earns its premium in three situations:
A space that changes use across the day — a boardroom that is a presentation room at 10am and a lunch room at noon.
Circadian-driven projects — senior care, healthcare, and any build chasing a wellness certification.
Retrofit-risk mitigation — if you are unsure whether the client will want 3000K or 4000K, tunable white lets them decide after occupancy instead of after drywall.
Everywhere else, pick the CCT once and spend the difference on better optics.
OnCloud specifically
Liteline's Luna trims with WiFi OnCloud put the mix under an app rather than a wall control. That is genuinely useful for a homeowner who wants to tune the kitchen themselves, and genuinely unhelpful in a 40-fixture commercial install where nobody wants 40 devices on a WiFi network. For commercial work, ask us about the 0–10V variant instead.