Amazon is reportedly planning biodomes for its new Seattle campus which will be warmed by hot air from the firms' adjacent Westin Building data centers. However some data center experts have branded the idea of recycling waste heat as ‘greenwash’.

Under the proposed Amazon Seattle campus scheme, heat would be transferred from the data centers to Amazon’s office buildings via underground water pipes. The cooled water would eventually be returned to its Westin Building to absorb more heat in the data centers.

Two resolutions have been approved by Seattle City Council, but the overall plan  - to heat buildings on the three-block campus – has yet to be finalized.

“People use waste heat from server farms but you don’t hear about tying it in with buildings across the street from each other,” said Seattle City Council member Mike O’Brien. “My understanding is the waste heat from this facility is significant enough to support more than just those three.”

O’Brien said he saw the project as a first step toward a district wide energy system. Seattle City Council is offering credit to owners of new construction who build hydronic heat systems, with data centers at Fisher Plaza and a  local sewer line already part of the scheme. However, Councillor O’Brien told newspapers he “wasn’t sure what kind of arrangement Amazon, [and others] had set up.”

That is because this is ’not core business’, said energy expert Professor Ian Bitterlin, Emerson Network Power’s CTO, who described the initiative as “greenwash to keep Greenpeace at bay”.

Though this is a quantifiable reason for the project, there is no case for UK data centers to follow suit, according to Bitterlin. “The waste heat is low grade with a temperature of around 33C and can’t be exported very far so has to be consumed on site. Data centers are power intensive so the load for the waste heat has to be huge.”

There are successful schemes recycling waste heat from data centers, but these are generally based on watercooled servers, which whose hot water output comes at a higher temperature.

Only the hyperscale players like Google and Amazon can guarantee full load to justify the investment and make the use pay for itself, said Bitterlin.

“The bottom line is that it costs too much CapEx, Opex is too high and it’s often land-hungry,” said Bitterlin, “the financial model is poor in comparison with building more data center.”

A spokesman for London based Virtus Data Centers said its Excool technology means it doesn’t have much waste heat to recycle.