Demolition and reconstruction are not always the only route to a better tall building. Many tall buildings, even the oldest ones, have soundly built structures and exterior construction-making refurbishment the preferred alternative to tearing down. Buildings are refurbished for many reasons, from unexpected damage, maintenance issues or desired changes in style to energy issues and the need to modernise outdated systems. Whole-building refurbishment can be more complex than the initial process of constructing the building. However, refurbishment is able to take advantage of the original structural shell of the building while modernizing everything from MEP (mechanical, electrical, plumbing) systems to curtain walling and interiors, usually at significantly less cost than it would take to rebuild completely. Analysis of a recent landmark tower project showed that refurbishment would cost no more than $300 million, as opposed to an estimated demolition and rebuild cost in excess of $1 billion. Refurbishment can also be more environmentally friendly than new construction in terms of overall embedded energy.