Microsoft trials timber-built datacentres to reduce built emissions

Claims embodied carbon footprint of two new datacentres will be 35% less than conventional steel structures

Microsoft is experimenting with the use of cross-laminated timber (CLT) for building two new hyperscale datacentres in Northern Virginia.

Instead of the usual steel and concrete used in datacentre construction, Microsoft decided to incorporate a fire-resistant prefabricated wood material called Cross Laminated Timber (CLT) in its latest datacentres to reduce embodied carbon emissions.

Cross-laminated timber is already a staple of low-carbon building in the European Union, but it hasn’t really caught on in the U.S. yet. A Microsoft spokesperson sad:

"CLT is one of the many Low Embodied Carbon material options available in the market and we evaluated our material options based on Embodied Carbon and regional availability of materials among other factors."

Microsoft estimates that using this material for parts of its datacentres will cut its carbon footprint by 35% versus steel construction. Greenhouse emissions are reduced by an even greater 65% when CLT is substituted for precast concrete.

The carbon savings come in because CLT is considerably lighter than concrete, meaning that less steel is required to hold up the building. Concrete and steel are high emissions materials because of the very high temperatures required to manufacture them – temperatures that require coal to achieve. Concrete and steel are also heavy and therefore burn more fuel during the transportation phase of their lifecycle.

The hyperscaler is not building these data centres completely from wood. But it is replacing the concrete used in floors and ceilings with CLT and then applying a thinner layer of concrete to make the wood last longer and protect it from the elements.

Carbon negative by 2030 - maybe

These “hybrid” datacentres are the latest innovation in Microsoft’s attempts to decarbonise its cloud operation. Microsoft has the toughest decarbonisation targets of any of the hyperscalers. Whilst it isn’t the only one to pledge to be carbon neutral by 2030, the company has also promised that by 2025 it will remove the equivalent of all the carbon it has created since its inception.

Laudable goals indeed, but just as with its nearest cloud competitor Amazon, Microsoft has succeeded in reducing its direct emissions by a small amount. However, indirect emissions have risen five times more, not only cancelling out the reduction in direct emissions but significantly enlarging the hyperscalers’ carbon footprint.

Microsoft is enormously profitable and powerful. There are levers it can pull and the company can show the way for other, smaller datacentre providers. One of those levers pushes the requirement to decarbonise down the supply chain.

“A lot of our suppliers are on the same journey as we are,” says Richard Hage, who leads global strategy for datacentre engineering at Microsoft. Everyone is implementing key initiatives to lower the embodied carbon of their materials and their products.”

Microsoft is also changing contract language to include low-carbon requirements for materials and equipment used in datacenter construction. Select high-volume suppliers will be required to use 100 percent carbon-free electricity by 2030 and investments in low-carbon building materials are being ramped up in a bid to accelerate commercial supply.

If the use of CLT in these datacentres proves successful and durable, the impact on wider datacentre industry carbon emissions could be positive. The hyperscalers all made their climate pledges around 2020 – before the GenAI boom that has seen the demand for datacentre infrastructure skyrocket. All of them are struggling with escalating indirect emissions from construction.

AWS has been pioneering the use of recycled steel in some of its US datacentres, and Microsoft’s trial of CLT has similarly promising potential in terms of modelling and de-risking not just to the wider datacentre industry but beyond. A Microsoft spokesperson said:

"The use of CLT as a building material has seen a resurgence over the past several years. Building code updates have helped spur adoption for use in multi-story buildings. Our goal is that using this material in our datacentres will be a catalyst for inspiring broader adoption within the datacentre industry."

If the trial is successful, Europe is an obvious choice for scaling. The spokesperson continued:

"Microsoft is continually evaluating the materials we construct our datacentres with. CLT is one of the many low embodied carbon material options available in the market and we will continually evaluate our material options based on Embodied Carbon, regional availability, and other factors.

“CLT will be evaluated as a material option for us globally, not just in the US. Some European markets may have a more mature CLT market, which could encourage use of CLT in those regions."