public function buildTimeZone()
    {
        if (null !== $this->value) {
            $sign = $this->value < 0 ? '-' : '+';
            $value = intval(abs($this->value) / 60);

            return new DateTimeZone(sprintf(
                '%s%02d:%02d',
                $sign,
                intval($value / 60),
                $value % 60
            ));
        }
    }