Data Center Handbook

23Raised Floor versus Overhead Cooling in Data Centers

Vali Sorell

Syska Hennessy Group, Charlotte, NC, USA

23.1 Introduction

There have been two schools of thought on how to deliver air to uncontained data halls. (There are other methods too, but the two discussed here are the main ones.) On the one hand, data centers have historically been provided with upflow air distribution using perforated tiles in a raised floor environment. On the other hand, telecommunication (telecom) central offices have historically been built on concrete floors using overhead air distribution with downflow air distribution into aisles. Both methodologies have served their respective industries well for many years.

In the past several years, there has been a convergence of functions under which the differences between telecom spaces and data hall spaces have almost disappeared. The reasons for this convergence relate more to the functions of the IT equipment itself, and are beyond the scope of this chapter.

Members of these two schools have, in general, continued their accustomed practices, following the belief that their respective practice is the better means to provide cooling airflow to the IT equipment. Designers who have come to the industry after the convergence of the two types of equipment find themselves in the middle and ask the question: “Overhead or under-floor?” There is not a definitive or correct answer—both methodologies must be understood since there are advantages and disadvantages ...