Why not just fill the cavity, then?

When I've explained our plans to wrap a bungalow in strawbales (even when I just say "externally insulate it") a number of people have asked why we don't just fill the cavity to insulate it.  It's becoming quite irritating, but that's my problem not anyone elses.  It does deserve a proper answer, which sort of serves as an example of what's wrong with general standard construction too.

The rented bungalow we currently live in does have insulated wall-cavities, and around 35cm depth of glass-fibre-blanket loft insulation (albeit poorly fitted with lots of gaps between rolls and an area in the centre with no extra blanket at all, apparently to leave the existing boarded area free for storage).  The windows are all double glazed (more on them later).  So it should be nice and warm and efficient to heat, then?

Nope.

In winter it gets cold very quickly once the heating goes off (ie: the heat escapes quickly through the walls, window, roof and the cold uninsulated floors).  In summer it gets very hot when the sun is on the building.  According to our latest gas bill (we have no gas cooker so our gas use is only for heating and hot water) our average daily usage for the last 3 months is 38kwh.  According to Which that's about average for non-condensing boilers, equalling a yearly bill of £760 in our case.  That will increase as it gets colder though.  It's been unusually warm lately; we used much more gas this time last year when it was so much colder.

Planning permission progress report

Yesterday we got official confirmation that our planning application has been received and registered.  The full details (all 20 documents of application 1/D/11/001941...) are now available for viewing and comment on the council's website (apart from brief down-time for maintenance this weekend).  So it's passed the bureaucratic hurdle of validation, has been allocated a case officer, and things are moving along.  The planning officer allocated to the case should be making a site visit shortly (I still don't know whether or not we show them around or whether they just go and have a look from the street). The application is open for comments until 23rd December, so with luck we should get a decision early in the new year (they say we should hear by 12th January 2012).  Keeping fingers crossed.