With the air conditioning on, the app's answer is the same as in any room: it goes by the temperature of the room where your baby sleeps. That can differ from the number set on the remote, so check the room itself and read its row.
What the app suggests for sleep in a cooled room, for a baby up to a year:
26–30°C: short-sleeve bodysuit. Warm room — a single light layer is enough, no sack needed. 24–25°C: short-sleeve bodysuit (0.5 TOG). A light 0.5 TOG sack over a short-sleeve bodysuit. 21–23°C: short-sleeve bodysuit (1.0 TOG). A 1.0 TOG sack over a bodysuit is a good start. 18–20°C: long-sleeve bodysuit (2.5 TOG). A 2.5 TOG sack over a long-sleeve bodysuit.
And awake, at home in the same room:
24–30°C: short-sleeve bodysuit. Warm at home — one light layer is likely plenty. Bare legs are fine. 21–23°C: short-sleeve bodysuit and socks. Comfortable room — a light top and socks. 18–20°C: long-sleeve bodysuit, pants and socks. A normal room — one light layer head to toe.
The Lullaby Trust recommends a room of 16–20°C for a baby's sleep. In a room cooled that far, a sleep sack of the TOG for the room does the job: a warmer sack for a cooler room, and never a blanket on top.
If the room cools through the night with the air on, the row for the cooler room is the one to read. A baby is safer slightly cool than too warm, so the app never suggests a warmer sack than the makers' chart for the room.
From 26°C, with the air on or off, a single light layer and no sack. A fan can move the air, just not pointed at the baby. Awake in the same room, the second table shows what to wear at home.
0–3 months, 24°C: short-sleeve bodysuit (0.5 TOG). 3–6 months, 24°C: short-sleeve bodysuit (0.5 TOG). 6–12 months, 24°C: short-sleeve bodysuit (0.5 TOG). 1–3 years, 24°C: short-sleeve bodysuit (0.5 TOG).
Never a hat for sleep — a baby cools through the head.
A sleep sack, never a loose blanket.
Safer slightly cool than too warm: nothing makes the sack warmer than the chart.
A fan can move the air — just not pointed at the baby.
Check the neck — warm but not sweaty means just right.