A Practical Architectural Approach to Mixed-Mode Ventilation: Airflow, Comfort, and Cooling

Earn 1 AIA HSW LU.

Operable windows play a key role in how air moves through buildings, supporting both ventilation and passive cooling strategies. In mixed-mode buildings, the design requirements for delivering fresh air to occupants can differ significantly from those needed to remove heat, making it essential to clearly define performance objectives early in the architectural design process.

This webinar provides practical, architecture-focused guidance on integrating operable windows into building design, focusing on airflow strategies such as single-sided, cross, and stack ventilation. Participants will explore how façade design, window placement, and building layout influence airflow performance, as well as how to estimate and evaluate opening areas, including the difference between geometric and effective opening area.

Through real-world scenarios, including both new construction and renovation, the course emphasizes what is possible within common design constraints. It also introduces key operational considerations such as adaptive comfort, occupant behavior, and the relationship between natural and mechanical systems. Attendees will gain a clearer understanding of how to align design objectives, building conditions, and window strategies to support effective and realistic mixed-mode ventilation solutions.

Learning Objectives

• Differentiate between ventilation and cooling objectives and how they influence operable window design strategies.
• Explain how wind pressure and thermal buoyancy drive natural ventilation, and how architectural design decisions impact airflow performance.
• Apply methods to design and evaluate operable window opening areas, including geometric and effective opening areas.
• Assess how building conditions, design constraints, and occupant behavior influence mixed-mode ventilation strategies, including operational considerations and adaptive comfort.

Imola Frei

Business Development Manager, East Coast US & Canada

WindowMaster Clearline Inc.

Imola Frei

LEED AP

Imola Frei is a Business Development Manager at WindowMaster, supporting projects with natural and mixed-mode ventilation strategies across the East Coast United States and Canada. She collaborates with architects, engineers, façade consultants, and sustainability teams to develop and implement automated natural ventilation solutions, providing technical guidance on airflow strategies, façade integration, and system application in high-performance building design. Her work focuses on aligning design intent with technical implementation to deliver climate-responsive ventilation concepts that enhance indoor environmental quality and reduce operational energy demand. With a background in product design engineering and experience in architecture and sustainability consulting, Imola supports project teams from early design through implementation. She is a LEED AP BD+C and holds a Master of Science in Product Design Engineering.

Kasper Højmark Ravn

Building Performance Engineer

WindowMaster

Kasper Højmark Ravn

Kasper is a Building Performance Engineer at WindowMaster and part of their Ventilation Institute. He plays a key role in the natural and mixed-mode ventilation strategies of WindowMaster in Europe and North America including Building Performance Simulations, Life Cycle Analysis and Building Codes/Standards. His area of expertise is to support the stakeholders of building projects such as Consulting Engineers and Architects to achieve successful passive ventilation designs with a focus on sustainable solutions and wellness of building users. Kasper has a MSc in Civil Engineering from the Technical University of Denmark (DTU) specializing in the Indoor Environment, HVAC and Sustainable design.