Hi and thanks for the question.

Firstly, the 20% factor of safety is only required for target setting studies (so if you’re conducting a full LCA it’s not required).  This was a concession by the City of Vincent.  The policy is pretty clear that the study should meet the EN15978 requirements for an LCA, and a Target Setting (using whole building templates) clearly doesn’t comply in terms of data quality. The city did however see that the Target Setting offered a lower cost option for developers at the Development Approval stage and was hence attractive.  They recognised the accuracy issues with target settings and hence agreed that a factor of safety is required.  It’s not an eTool directive, rather a city of vincent directive.  We gave them the idea as we used to apply the factor of safety anyway as we felt it was good practice. Essentially we agreed to support the pathway as although eTool will loose out commercially (it’s lower cost to deliver target settings than full LCA studies) the planet wins (as the developer is agreeing to over-perform a bit).

It should also be noted that the factor of safety is not just for assessing the accuracy of the strategy itself but also giving the stakeholders a buffer in case the actually base design modelling is not accurate.  

So in summary, if you’re conducting a full LCA, not factor of safety required and it’s not an eTool requirement so to ask for a concession you’d need to chat to the City of Vincent. 
It’s really good that you’ve scrutinised the recommendation template. These are just suggested ways of documenting the strategies and we encourage users to edit as necessary. Regarding the availability of high efficiency Aircons, I am not sure if you project is residential or commercial.
If it’s resi there’s plenty of split system units that meet that EER / COP hurdle.  See this sheet I prepared from a current download of MEPS Registered Air Conditioners (the summary filters for Available Units and sort by COP / EER).  There’s well over 100 products products that meet the hurdle set in the eTool Recommendation template offered by major brands such as Daikin, Mitsubishi, LG and Toshiba (and according to the list nearly 300 products in total). If it’s commercial property, using a packaged cooling tower would probably deliver a cooling COP of 6 or more.  

I hope that helps.