The Gro-suit is intended for use with a Grobag in cold weather or in room temperatures of 18°C or under. They are most suited to be used with a 2.5 tog or 3.5 tog Grobag.
If your room is under 16°C and you’re using a 2.5 tog Grobag you should add a vest underneath your Gro-suit. However, if you’re using a 3.5 tog Grobag you only need to use the Gro-suit underneath.
If your room is under 14°C you should ideally look to increase the temperature of the room, or use a 3.5 tog Grobag, with Gro-suit and vest.