cubicsupport wrote:
I have 2 Aluminium sliding patio doors in the house installed around
1975, by the previous owners. During the recent cold spell, I have
notices the cold temperature of the aluminium frame compared to the
temperature of the UPVC frame in the rest of the house. Is there a wat
to reduce the heat loss via the aluminium frame or Do I need to
consider replcement with UPVC.

The aluminium will always feel colder because it conducts heat away from
the hand more quickly than PVC. However the heat loss through the frame
might not be any more than through a PVC frame (PVC frames contain metal
to strengthen them anyway) and is likely to be insignificant compared to
total heat loss through the glass.

If the doors are draughty or single glazed then there may be reason to
replace them on comfort grounds, but it's unlikely to make much
difference economically. Interlining your curtains with bubblewrap will
be cheaper.

Owain