Here are some useful links of the legislations & information on the air-conditioning system installation :

BCA Air-con Bracket Safety : http://www.bca.gov.sg/Owners/owners.html

HDB InfoWed Guidelines for Air-Conditioners Installation Works : http://www.hdb.gov.sg/fi10/fi10324p.nsf/w/HomeRenoGuidelinesAirCon

HDB InfoWed  Purchase of Residential Floor Plan : https://services2.hdb.gov.sg/webapp/BC31ISOP2/BC31SMain

  Go Green : Check on NEA Energy Labelling Scheme Product Search & Energy Calculation : https://e-services.nea.gov.sg/els/Pages/Search/PublicSearchProduct.aspx?param=goods&type=p

  Go Green : Check on NEA Products Tick Rating : http://app2.nea.gov.sg/energy-waste/energy-efficiency/household-sector/tick-rating