Air pressure testing of new homes

I have recently started Air pressure testing new homes for part L of the building regulations.
I will put down some of my experiences here and see if anyone is interested in them.
Firstly why Air pressure test homes at all ? Well we are all aware of the cost of heating our homes and the environmental cost to the environment in terms of CO2 emissions. This is because most of our homes are heated either directly by fossil fuels e.g. gas or oil or by electricity created by burning fossil fuels at the power station. Hew homes have to be energy efficient and the key control to this in England and Wales is contained in the Building regulations Part L. The standardised method of calculating heat losses from buildings for Building regulations purposes is is called SAP 2005 commonly known as SAP calculations (STANDARD ASSESSMENT PROCEDURE don't confuse this with SAP AG ERP Business Software).The Procedure results in 2 key figures the Dwelling emission rate and the Target emission Rate. Basically the Dwelling emission rate for your dwelling has to be lower than the Target emission rate for the dwelling in order to pass building regs. One of the many factors included in the DER calculation is Air leakage. The greater the air leakage the greater the heat loss and so this pushes up the DER. Therefore dwellings with a lower air leakage have a better DER and this makes it easier to pass the building regulations. The air leakage rate is set during the SAP calculation at design stage and is confirmed on construction once the dwelling is complete by an air leakage test. This seems to have various synonyms Air leakage test, air permeability test, air admittance test, airleakage test. In relation to dwellings these are all the same thing.