AIRTIGHTNESS...
a breath of fresh air or just a bag of wind?

Apparently buildings are very leaky. No, not water but air. The problem appears to be that if you want your building to be warm when it is cold you don't want to heat up lots of air that just escapes out of all the holes.
Some of the holes are so tiny that you can hardly see them but there might be lots of them (buildings are made of thousands of bits that go together...so it's bound to be a bit difficult to seal it all up).

So buildings are now 'airtested' to see if they meet the standard. so big fans are put in the doorways and taped up and then they pressurise the building and then sensors monitor the pressure at points all over the building and from the readings on the sensors and the speed of the fans you can work out how much air is leaking out.
You have to do lots of sums to work out how much surface area the building has, how much air is leaking out and then how much air leaks outs in cubic meters for every square metre of area each hour at a special pressure of 50 Pascals.

To pass the test the building must get lower than 10. Weird...it's actually better to get a lower score!

We helped take the readings. Each test took 30 minutes. Watch the video to see how windy it was.