That is a very good question, yet hard to answer without knowing all the
details about your house and its construction. In fact if I think back, mostof the row houses I saw in Philly had brick exteriors with very little areafor siding if any.
With that and in short, insulated siding is a joke for themost part and probably won't help you reduce your bills contrary to some ofthe claims out there.
You really do need to have an experienced energyauditor come in and look at everything at once and present you your options.
While there are many types of audits, you want one that will be using ablower door, infrared, and a snake cam.
- If your exterior is not brick, the auditor may call for removing the vinyl, takingit down to the sheathing & adding R10 or more on the exterior.
- The auditor may evenopen it up further and after dealing with any electrical issues (do notinsulate around knob and tube or older type wiring) they may dense pack thoseareas.
Assuming the outside is brick, if they determine (or you fix) any electrical and/or water infiltration issues the auditor may recommend drilling some holes in theplaster and dense packing it with cellulose.
For more information:
Read "We have inadequate wall insulation. What is the best approach to insulate our walls?" a Q&A answered by Michael Holcomb.