new \DateTime() returns an object where the timezone is already set to the user's time zone.

date.php

<?php

    $time = new \DateTime();
    $default = $time->format('d.m.Y H:i');
    // 18.10.2016 12:17

    $user_timezone = drupal_get_user_timezone();
    $timezone = new \DateTimeZone($user_timezone);
    $time->setTimezone($timezone);
    $with_user_timezone = $time->format('d.m.Y H:i');
    // 18.10.2016 12:17

    $timezone = new \DateTimeZone('UTC');
    $time->setTimezone($timezone);
    $with_utc_timezone = $time->format('d.m.Y H:i');
    // 18.10.2016 11:17