Fitting blinds and secondary glazing

[hathaer1]

Hi, I have had secondary glazing fitted to the 2 bedrooms in my flat for heat and sound insulation due to it being a listed building.

I would like to fit some blackout blinds and have decided on some cellular blackout blinds as these seem to have even more heat insulation properties.

My question is regarding sound and heat insulation, would it be better to fit these on the inside of the secondary glazing or in the space between the secondary and original windows?

thanks

 

[foxhole]

They will do little for sound insulation, fit internally for insulation properties.