Chipping Away at Embodied Carbon: Wooden Datacenters Take Root

While construction materials are among the most challenging aspects of datacenter development to decarbonize, our Virginia project makes a significant leap toward carbon-negative territory by utilizing wood construction. At our newest datacenter in Virginia, we piloted a datacenter built with cross-laminated timber (CLT), demonstrating that replacing concrete and steel with mass timber to reduce the embodied carbon in datacenter structures is a major step toward carbon-negative buildings. Using biogenic materials like mass timber pulls CO? out of the air as the trees grow and then locks it up in building materials. This contrasts with conventional materials like steel and concrete that are carbon-intensive when produced, contributing to embodied carbon or Scope 3 emissions.

Microsoft is pioneering the construction of a first-of-its-kind datacenter in Virginia using structurally sound and lightweight wood to significantly reduce steel and concrete content. This pilot project demonstrates that timber is a viable, carbon-negative alternative for large-scale industrial construction. Engineers have developed a hybrid approach utilizing cross-laminated timber, a fire-resistant, prefabricated wood material. Building with mass timber is estimated to reduce the embodied carbon of new datacenters by 35% compared to conventional steel construction and by 65% compared to typical precast concrete structures. Emissions from steel and cement production account for about 7% and 8% of global carbon emissions, respectively.

In this specific project in Virginia, CLT replaces a significant portion of the thick concrete typically used for flooring and ceilings. This results in lighter construction requiring substantially less steel, further reducing embodied carbon. Prefabricated offsite, CLT can be installed more quickly and safely than traditional materials like corrugated steel. While CLT may increase material costs by 5% to 10% compared to traditional timber, for large projects such as datacenters, it becomes cost-effective due to reduced construction time, lower labor requirements, and economies of scale.

Before making a disruptive move in mission-critical industrial design, we spent a lot of time ensuring we understood the risks. Several perceived risks were identified, including increased fire risk and mold from condensation in humid climates and evaporatively cooled datacenters.

Datacenters typically have a low fire risk by maintaining best practices, such as keeping flammable cellulosic materials like paper and wood pallets out. However, the fire resistance of timber is actually very good, and there are standards like Eurocode 5 and ANSI/APA PRG 320 that define its fire-resistant nature.

Humidity, on the other hand, can be an issue in datacenters, especially those that use energy-efficient evaporative cooling. To assess the risks of humidity on timber construction, we used hygrothermal modeling software (WUFI) to evaluate thermal, moisture, and humidity impacts on mass timber elements. We also conducted extensive research to review existing academic findings on risk factors and mitigation strategies for mass timber performance in hot and humid conditions. The key findings revealed that mass timber has been successfully used in high-humidity applications such as indoor pools. Additionally, our hygrothermal analysis in evaporatively cooled datacenters shows a low risk of mold growth, rot, decay, and dimensional instability in mass timber, with internal and external conditions not creating significant moisture performance risks.

Building with timber does require some special engineering design considerations. To optimize mass timber moisture performance, it is essential to:

• Maintain air tightness at the vapor barrier and ensure proper air sealing for the roof assembly.
• Elevate timber columns on plinths to avoid contact with concrete and standing water.
• Design details to eliminate cold spots in members and joints.
• Specify wood species that resist water uptake.
• Keep mass timber elements dry (below 8% moisture content) during transportation, storage, and construction.

The use of carbon negative mass timber in mission-critical industrial construction, particularly in datacenters, shows that with planning and adherence to best practices, perceived risks such as fire hazards and moisture-related issues can be effectively managed. Our comprehensive analysis and the practical application of hygrothermal modeling confirm that mass timber is not only viable means of decarbonizing construction but also a resilient material choice. By prioritizing air tightness, proper material selection, and moisture management, architects and builders can unlock the full potential of mass timber, ensuring both safety and longevity in their innovative designs.

#GreenBuilding #Sustainability #Datacenters #MassTimber

Microsoft builds first datacenters with wood to slash carbon emissions - Source