Week 28, 11th November:  Fireworks, Air Test, Solar Panels

Here we are - with the best seat in town, perched on the very top of the roof to watch the fireworks at Sherborne Castle on Saturday evening.  

We had all the necessary refinements for a civilised evening, including a bottle of Prosecco and some olives; the only problem was what to do with it all. The half empty bottle presided very nicely against the MVHR vent but sadly the olives slid very slowly down the roof.

                    

There has been a big build up to today's Air Test.  

It is necessary as part of the SAPs calculation so that 

we can get the solar panels registered and will ultimately be needed for the EPC (Energy Performance Certificate) so we will need to have a final one done in about 6 months time. If the score on this is not up to the required standard, they can pinpoint the areas of weakness so that these can be addressed.  Basically the house was closed up, a sheet was fitted over the side door with a big fan in it which sucked air out of the house and digital readings were taken for both the upstairs and the downstairs.  We were delighted as we achieved a score of 1.62 - anything below 5 is acceptable; the chap basically said that even if we blast a hole in one wall we will still pass next time.
Air tightness is measured in cubic metres per hour, per square metre of building envelope (walls+floor+roof) at a pressure differential of 50 Pa. One atmosphere is about 100,000 Pa so this is a very small pressure difference!! A perfect Passiv Haus could achieve as low as 0.5 air leakage, we hope to improve as walls and ceilings are sealed and plastered.

The upshot of all this is that any unpleasant smells linger for quite a long time - but it will all be OK when the MVHR leaps into action.

Update on the stone cladding:

We have applied to West Dorset District Council for a Non-Material Amendment to replace Century Stone with another product from EuroBrick Systems Ltd (more about this when it actually happens), so yet again we are in the hands of the Planning Department.

However, the problem which has proved to be the most challenging so far to resolve, reared its head most unexpectedly last Thursday.  We had chosen to get some solar panels from Environmental Logic.  Back in September, when the roof tiles were going on, we had a site visit and David asked about fitting brackets before the tiles which we hold the panels in place.  They assured him that they had their own fixing system which was preferable to brackets, so we bowed to their experience, didn't insist and the roof tiles were laid.  They arrived on site last Thursday to fit the panels, wanted to drill holes all over the new tiles which Reeves wouldn't let them do.  If the screw holes allow any water seepage the water would drip down into the SIPs panels until they blow apart; it would take a long time for any damage to be apparent.  To cut a very long story short; the panels need to be fixed in place by some limpets (from Solar Limpets); adhesive which is normally used sticks to anything apart from Tapco Slate.  We sent some tiles off to Solar Limpets for testing (which failed) and we have carried out exhaustive tests on different adhesives ourselves.  In the middle of the night last night, we were almost abandoning solar panels altogether - which should be an almost unthinkable course of action but the prospect of having to strip the roof tiles off and start again in order to fit the brackets was a frighteningly time consuming and expensive only other course of action we could see working.  Anyhow, David put his great engineering mind to the problem and after much discussion with all parties involved has tonight written an enhanced method statement to satisfy and cover everyone's responsibilities.  Basically we are now going to fit the limpets almost as directed (with the screws in a slightly different position) but then there will be lead flashing over and extending 100 mm in all directions beyond each limpet.  We now have a new installation date for the solar panels of 26th November, so there will be photos of David's masterful system then.