Assessment of air-tightness of windows
I'd look for a "home energy auditor" or an "energy efficiency auditor" in your area.  

For air-tightness, they'll typcically do a blower door test, which basically uses a huge fan to slightly pressurize the interior of the house v. the outside air pressure.  Then they go around and check for pressure leaks.  Locally, our electrical utility will help you arrange energy audits (and will sometimes offer rebates, etc.).  That may be another avenue to check if you have trouble locating a professional in your area.