def usage15minTo1hTransform(usage_list):
    """Transforms series of water usage in 15 minutes intervals into 1 hour intervals.

    :param usage_list: list of numbers
    :return: list of numbers(usage hourly)
    """
    usage = []
    for i in range(0, len(usage_list) - 1, 4):
        h = float(usage_list[i]) + float(usage_list[i + 1]) + float(usage_list[i + 2]) + float(usage_list[i + 3])
        usage.append(round(h, 2))

    return usage