Insulation of water pipes in an unheated room

[DC]

Can someone advise me for the insulation of water pipes in an unheated room?

The cellar is only dug under part of the house and does not communicate with the room under the kitchen and the bathroom at the back of the house, hence the obligatory passage of distribution water ( counter in the cellar at the front of the house) towards the rear of the house, departure from the various domestic water supplies.

It is necessary to insulate the water pipes in a box because the room through which they pass is located under the unsheltered terrace and overlooks the garden (no door currently), it is not heated.

HOW TO INSULATE THE CONDUITS AND THE BOX ITSELF?

1. WELL insulate the room under the terrace:
the room is dark, a French window with double glazing is better or as well than a wooden door?

2. WELL insulate the cabinet
The 4 pipes (2 sanitary cold water + 2 central heating) will be arranged close to each other in an 18 mm plywood tank leaning against the stone wall at the corner with the ceiling over the entire length (6-7 m) and supported by brackets.
The gap between the edge of the horizontal planks and the wall will be closed with polyurethane foam.
- the inside of the boards of the box will be covered with Frigolithe: WHAT THICKNESS?
- the pipes (individually isolated by climatubes ???) will be "drowned" in glass wool.

3. WELL isolate the water pipes: WHAT OPTION TO CHOOSE ?
3.1. insulate the 4 pipes with climatubes
3.2 do not insulate the pipes with climatubes except the pipe going to the radiators with the hope that the heat diffusing from the return pipe of the central heating water will be sufficient to avoid that the water freezes in winter in the cold water pipes, especially if the central heating was interrupted or I decided to replace the central heating with another without a radiator.
In this case will the return water from the radiators be further cooled in the box, which is however lined internally with frigolite and glass wool (+/- 6 m long)?

THANK YOU FOR YOUR OPINIONS AND SUGGESTIONS!