With singapore's hot weather and overall rising temperatures, window films are becoming more popular. It is cost effective to block out a great amount of heat and increase comfort levels. Do look out for the different types of film - mainly ceramic film, metallic film or sputtered film. Sputtered films are more effective in blocking heat as it reflects heat away, and do not have the mirror like effect which can be ugly and also is against BCA Laws. Do let me know if anyone have other questions.
If you are looking for long term solution to block the sun and heat, i would recommend that you do not DIY. Engage a professional to do the job for you, warranty up to 10 years. Effective and you can have a peace of mind.