It's one of a growing number of startups offering energy management tools for data centers, many of which are being forced to undertake costly expansion projects because they are running out of power at existing facilities.

A this month from wholesale data-center provider Digital Realty Trust found that more than a third of respondents plan data center expansion projects this year, and that the need for additional power was the top reason for those projects, up from fifth place last year.

Viridity's new EnergyCenter tool, like comparable ones from Arch Rock, Sentilla and other startups, aims to calculate how much power is being used by IT equipment, root out idle or inefficient machines, and identify pockets of surplus power that could accommodate new equipment.

Viridity's product manages only servers today, but the company will add storage equipment in a few months and network gear soon after that, said Kevin Rogers, a member of Viridity's field services team.

EnergyCenter starts by compiling an inventory of the servers in a data center with a tool that scans the network using the SNMP, WMI and SSH protocols, as well as VMware's vSphere API. It then monitors the utilization rates of those servers at 5- to 30-minute intervals, depending on how the customer sets it up.