Set the timezone in the config sample to UTC

application/config/config.sample.php

@@ -576,7 +576,7 @@ $config['compress_output'] = FALSE;
 | helper' page of the user guide for information regarding date handling.
 |
 */
-$config['time_reference'] = 'local';
+$config['time_reference'] = 'UTC';
 
 /*
 |--------------------------------------------------------------------------