Insulating doors and windows can be done. On the east coast people add storm doors and windows. However, there are a variety of pleasing window treatments that are far cheaper and cost effective than replacing windows with Low E, argon filled units. I'm sure you've seen honeycomb shades, they work well to insulate windows.

Measuring insulation efficiency of your walls and attic is usually done by measuring the depth of insulation and multiplying by the R value. However, I've used an infrared camera long enough to know that there can be gaps and areas that are not insulated (or poorly performing) for reasons like workers moving insulation and not putting it back, air flowing through it or rodents burrowing in and creating dens there. These are common issues.

There are two potential rebates/tax credits you may be able to use for insulation upgrades:

- PG&E offers insulation rebates (up to $500 for wall insulation and $150 for attic insulation).
- Additionally, you can use the federal energy efficiency tax credit to cover insulation upgrades, exterior doors, high efficiency windows and storm windows (30% of the cost of the project up to $1500 as a credit on your taxes).

Unfortunately, neither of the programs cover efficiency window treatments like honeycomb shades.