Office timing changes - early morning timings for summers - inputs to convince?

Our office timing is 10Am to 6:30PM with 15 min grace in morning.any employee can come till 10:15 AM.and employee takes 15 min to login system after various activities like hello, hi wishes and using washroom ,taking morning tea from machine etc.
Now i want to propose to management to have changes in timing since it is summer and Hot days and i feel early morning hours are more productive but i need reason to implement. Pls give inputs emphasising on how I could convince and incorporate.

What do your seniors and other employees feel?
Are you from HR?
What was done last hot season?
Train timings would not be an issue in Mumbai as there are plenty of trains.
You would need to sound out others opinion also as change of timings has cumulative effects on all employees and their already settled departure and arrival timings.

You may have to more questions to answer than getting a good solution to this summer issue by change in timings. It might not work as they may have to go back in the hot sun[very much like the schools] and may affect their family togetherness too, a factor to be taken into account. Unless your office area has issues with voltage, power etc better stick to the time. Some policies are best kept under wraps, this being one such policy.

You can give a 15 min like 5 morning, 5 lunch and 5 snacks time. If you want to mandatory 15 minutes

Dear Friend,
The office timing is reschudled in many part of the country in summer. There are states every year they issue notifications to restrict the workman from exposure to to excessive heat and sun to prevent casualty. In that circulars it is also mentioned that where people are generally working under shade not to be considered but their entry & exit should be in a normal condition of temperture. It is not always applicable to all the establishments specially run in shifts.
You need to understand the necessity than feelings. Always prepare a note sheet to place before the mangement for approval which speak of certain benefits than of loss.

Dear colleague,
The need for change in office timings is felt by you and any change imposed from outside, as you know , may meet with resistance.
Instead, try to create the need for change in their minds through informal talks and opinion leaders and gain acceptance.
Regards,
Vinayak Nagarkar
HR-Consultant