B&D Data Center á Grenoble – A High Standard for Sustainability Beyond PUE


courtesy of flicr user: fred_v

I had the fortune to attend the opening of the new B&D data center in Grenoble, France last week. It was a pleasure to visit beautiful Grenoble and see this new concept in sustainable data centers first hand. The thinking here in many respects seems truly unique in its scope for setting a high standard for sustainable data centers.

The B&D data center opened April 7 in Grenoble. The first point of interest about the data center is that it’s constructed in a pre-existing multi-story industrial building. To be sure this reuse constrains the use of some innovations like free-air or convective cooling, but reusing a building and an industrial site obviously reduces environmental footprint– also a huge contribution to sustainability.

Business and Decision.JPG

That said, the forecast electrical efficiency achieved in the data center at full build-out is an impressive PUE = 1.35 -  excellent for a Tier 3 data center (for instance comparable to Cisco’s recently announced Green DC). There isn’t a lot of room for air handling in the structure, so they employed a rack level system developed by Schneider to isolate hot and cold aisles. Such a solution achieves very high level of efficiency and would be an excellent retrofit model for existing inefficient data centers still using CRACs and floor tiles.

But the B&D data center is not just about achieving world class PUE, it is designed for a much broader perspective on sustainability. For instance, the engineers in the data center optimized their Power Factor , achieving an impressive facility level Power Factor of 97%. This point is often neglected, or infrequently reported.

The data center is powered by renewable energy (electricity from hydroelectric, photovoltaic, and GEG ENeR’s wind farm sources) and hence the facility is 100% carbon-free. Thus, on the basis of the new metrics of data center sustainability from The Green Grid, the CUE = 0. Comparable results for a data center powered entirely by coal-generated electricity would be on the order of 3kg CO2/kWh.

Another unique element is that the Business & Decision data center uses water from Grenoble’s underground aquifer for cooling. The water emerges from the ground at 14C and is returned at a temperature below 19C (In the future some of this heat wil be used to heat adjacent buildings). Via heat exchangers, an independent closed-loop cooling system within the data center is responsible for the actual cooling of the air circulation units.  This ensures essentially zero water use in the data center, and hence a site WUE  near zero. (no water is used for humidification). The folks involved in the B&D data center pointed out to me that in case of emergency, provision is made to be able to "consume" water to cool the data center. However, since this is a back-up scenario only those considerations are not included here). This compares to what might be a typical usage of 7.7 liter/kWh in a typical open loop data center configuration (in other words for a PUE 2.0 data center).

These results are summarized in the table below.








3.1 kg CO2 / kWh



7.7 Liter / kWh

*Based on assumed industry average PUE

**Based on US DOE estimates of carbon content from coal.

***Typical based on a reported 360,000 gallons per day for a 15 MW data center and PUE of 2.0

It’s interesting to contrast this on a per server basis for an assumed average power of 200W per server.

Per 200W server



Power  Overhead

70 Watts

200 Watts

Carbon per hour


0.3 kg/Hour

Water per hour


1.5 Liter/Hour

I encourage you to find out more about this state of the art data center by visiting them in person or online. If you are so privileged, you might even get a chance to peak at their online metrics page, where you can see real time the energy use, PUE, and other factors about the data center operation.

eolas B&D daa center indicator page.bmp