WITH IRELAND'S Building Energy Rating system now in operation, neighbours are getting surveys completed for cavity block insulation, interior fittings and external wall insulation systems such as the one shown at right. Even though I work with Amergin instructors who can recite the absolute effectiveness of all sorts of systems, I am a novice at external wall insulation--but I know it is more expensive than most other options. We may not have a choice in the matter because we have a kitchen extension with no insulation in its ceiling and a leaky windowsill all around. An external wall system gets my attention beause a thicker outside wall under our kitchen window could be used to support a long window bench someday. In addition, putting the insulation on the outside wall helps preserve all the internal space and that's a good idea. While we finalise our energy strategy, we're also draught-proofing our letterbox, insulating our primary pipework and finishing our loft space to eliminate excessive blow-through.