Microsoft tries out wooden bit barns to cut construction emissions

The two hybrid datacenters promise 35% less embodied carbon than steel builds, 65% less than concrete

Microsoft is experimenting with datacenters made out of wood in a bid to cut the growing greenhouse gas (GHG) emissions that result from constructing its expanding network of bit barns.

In Northern Virginia, Microsoft is erecting its first datacenters using cross-laminated timber (CLT), an engineered product made from layers of wood glued together at right angles to create panels for building.

It claims that the hybrid timber, steel, and concrete construction model being adopted for the two new facilities will reduce their embodied carbon footprint by 35 percent compared to conventional steel construction, and 65 percent when compared to precast concrete.

Microsoft has faced difficulties in meeting its environmental commitments of late, largely due to its aggressive program of expanding datacenter capacity to meet rising demand from customers wanting to run generative AI projects, and the cloud services connected with them. 

The tech giant disclosed in its Environmental Sustainability Report for this year that its overall emissions in FY23 were up 29.1 percent over the 2020 baseline, and this was largely blamed on indirect (Scope 3) emissions resulting from the construction and provisioning of all those new server farms. Not so great if your much-publicized ambition is to become "carbon-negative" by 2030.

Indirect emissions are difficult to manage because they include carbon emitted during the extraction, processing, manufacturing and even transportation of materials, and so they are outside Microsoft's immediate control. Those that are under its control were down by 6.3 percent.

In response to this, the cloud and software biz claims it has mobilized a company-wide effort to accelerate decarbonization, and using cross-laminated timber in its latest builds is part of this.

CLT is already used for buildings, even multi-story apartment blocks such as Dalston Works in London, which was claimed as the world's largest CLT building when completed in 2017. It was also used in the construction of Google's UK headquarters building at King's Cross in London. And Microsoft itself built its Silicon Valley headquarters out of CLT in 2021, representing its first large-scale use of the material.

According to a report on the material in New Scientist from 2019, CLT costs a bit more than steel and concrete, but it makes construction quicker, is surprisingly fire-resistant, and sequesters carbon for the lifetime of the building, typically 60 to 70 years.

In Microsoft's case, the CLT in its bit barns will replace some of the thick concrete typically used for floors and ceilings. To ensure durability and waterproofing, a thin layer of concrete will be applied for reinforcement, but even including that, the result will be a much lighter building requiring far less steel, Microsoft claims.

"We have to be system thinkers across the entire value chain of these materials that go into our datacenters and the equipment that supplies them," Microsoft's director of datacenter sustainability Jim Hanna said in a blog detailing its plans.

While Microsoft makes efforts to cut its own GHG emissions, the facilities it is building may ironically be used to help the oil and gas industries produce more fossil fuels for burning. As we reported this week, Microsoft is eyeing an opportunity of $35 to $75 billion annually in marketing its AI and cloud computing services to be used to aid fossil fuel exploration and production. ®