As the world intensifies efforts to reach net-zero emissions, urban environments are emerging as critical battlegrounds in the fight against climate change. 

One of the most promising technologies for removing atmospheric CO₂ is Direct Air Capture (DAC). Traditionally deployed in remote or industrial areas, DAC systems are now being reimagined for integration into the urban fabric—a move that could redefine how cities participate in climate mitigation.

The UrbanDAC Concept: A Synergy of Infrastructure and Innovation

A pioneering study by Oak Ridge National Laboratory (ORNL) introduces the UrbanDAC concept, which envisions the integration of DAC systems with commercial building infrastructure. This approach leverages the built environment—rooftops, façades, HVAC systems, and ventilation pathways—as platforms for carbon capture deployment. 

ORNL’s research underscores the potential of these systems to not only sequester CO₂ but also provide thermal energy recovery and indoor air quality improvements when coupled with existing mechanical systems.

The UrbanDAC model capitalizes on the underutilized surfaces and mechanical systems of commercial buildings, transforming them into active components of the carbon removal process. 

This approach supports distributed deployment, reduces land-use conflict, and offers scalability in dense urban cores.

Integrating DAC with Building Ventilation Systems

A study published in Building and Environment explores the technical feasibility of integrating DAC systems into building ventilation systems. By using HVAC airflows, DAC units can extract CO₂ from indoor or recirculated air before it is exhausted into the atmosphere. This method improves overall system efficiency and minimizes the need for separate ductwork or fans.

The synergy between DAC and HVAC systems also enables real-time monitoring and optimization of CO₂ levels, enhancing indoor air quality while contributing to climate goals. 

These systems can be modulated based on occupancy, air quality metrics, and ambient CO₂ concentrations, providing a responsive and dynamic carbon management tool within the urban setting.

Cost Implications and Lifecycle Performance

Economic viability remains a significant barrier to widespread DAC adoption. 

However, a recent analysis in Energy and Buildings provides a comprehensive life cycle cost assessment of DAC-HVAC integration. 

The findings indicate that while initial capital costs are higher, the long-term operational savings and potential revenue from carbon credits or government incentives could make these systems economically viable over a 20–30 year lifecycle (Energy and Buildings, 2025).

The study emphasizes the importance of design optimization and load matching, noting that systems integrated with energy-efficient buildings perform significantly better in terms of both cost and carbon capture efficiency.

Decentralized Solutions: The Yggdrasil Trees Initiative

Beyond integration into existing buildings, innovative decentralized models are gaining traction. 

The Yggdrasil Trees project introduces modular DAC units designed for urban environments. 

These bioinspired structures are intended for deployment in public spaces, parks, and rooftops. They offer an aesthetic and functional approach to decentralized carbon capture, capable of operating independently or networking across neighborhoods.

This model supports community engagement and urban greening, further aligning DAC deployment with urban sustainability goals.

Towards Carbon-Conscious Cities

Integrating DAC systems into the urban fabric represents a bold shift in climate strategy. 

By embedding carbon removal capabilities into the everyday functions of cities—buildings, ventilation systems, public spaces—urban areas can transition from passive emitters to active agents of decarbonization. 

With continued technological refinement, supportive policies, and strategic investment, DAC could become as integral to cities as energy grids and water infrastructure.

For architects, engineers, and planners, the message is clear: the future of urban design must not only accommodate human life, but also regenerate the atmosphere that sustains it.