Replacing bathroom fan with dmev

[agamemnon]

Hi there, 

 

I am becoming interested in making our house airtight. I am looking at dmev but we have a fan with a light in the bathroom and would like to replace with a dmev, I don’t want to impact the light loop while also not making the room darker. 
 

Suggestions in how to replace the fan with dmev and keep the room bright enough.

 

The fan is above the shower cubicle. 
 

Edited September 12, 2022 by agamemnon

[Nickfromwales]

23 minutes ago, agamemnon said:

I am becoming interested in making our house airtight

Have you yet discussed this, and convinced ‘us’ that getting an existing dwelling airtight is practicable? Not sure if you’ve looked into this fully yet? Horse needs to be in front of the cart  

[MarkyG82]

In a previous house I simply took the power supply for the in-ceiling fan and applied it to the new in-line fan and left the old fan in place as it was so weedy. Does the light have a separate supply to the fan?