for best result :-

1) install the aluminium foil e. monier radenshielf below the roof area.... involve removing the roof tiles... cost about RM3k for normal
    double storey house

2) install another layer of CSR Coolbatt above the ceiling area.. cost between RM2k-RM3k for 2 storey house

3) install tinted film...cost RM3k + for whole house...

4) put Nippon Solareflect paint on the outer area of your house...

guaranteed your house will be cooler !