Comfortable indoor air quality for a high-performance coffee shop retrofit. A passive house retrofit project in a historic Minneapolis building

Thesis Coffee, located in Minneapolis, Minnesota, opened in 2025 in a renovated 1931 Art Deco building. Originally constructed as a retail store with two apartments above, the building is being transformed into a mixed-use space that includes a coffee shop and office areas.

A ventilation challenge driven by increased occupancy

High-performance ventilation with heat and moisture recovery

To address the ventilation demands, a Swegon CASA R9 energy recovery ventilator was selected as the primary ventilation solution.

The PHI-certified unit provides 79% heat recovery efficiency, reducing heating demand during winter and cooling demand during summer. During a recent winter visit, outdoor temperatures measured 17°F while the supply air delivered by the CASA R9 reached approximately 63°F, helping maintain a comfortable indoor environment with minimal additional heating.

Humidity control is also achieved through the energy recovery process. The heat exchanger delivers up to 84% moisture recovery, helping maintain indoor comfort throughout the year while reducing energy consumption.

Demand-controlled ventilation was implemented using integrated CO₂ sensors connected to the CASA control platform. When occupancy increases and indoor CO₂ levels rise, ventilation airflow automatically increases. When occupancy decreases, airflow is reduced to standard operating levels. This strategy prevents over-ventilation while maintaining healthy indoor air quality and minimizing energy use.

Airtightness and future building envelope improvements

Airtightness is a key principle of Passive House design and plays an important role in ventilation performance. Tight building envelopes reduce uncontrolled air leakage, while airtight ventilation systems prevent energy losses and unwanted air transfer.

Future phases of the project will include:

Continuous exterior insulation
Air barrier improvements
Building envelope air sealing
Evaluation of Aerobarrier technology

These upgrades are expected to further reduce energy demand and improve overall building performance.

Low energy use and improved occupant comfort

The combination of high-performance ventilation, heat recovery, moisture recovery, and demand-controlled airflow contributes to a low-energy building operation while maintaining excellent indoor environmental quality.

Project benefits include:

Reduced heating and cooling loads
High indoor air quality
Improved occupant comfort
Low electrical consumption
Quiet operation
Reduced carbon intensity
Demand-controlled ventilation
Passive House design principles applied to an existing building

The project demonstrates how advanced ventilation technology can support deep energy retrofits and help historic commercial buildings achieve modern performance standards.

A demonstration project for future retrofits

Thesis Coffee serves as an active demonstration site for high-performance retrofit technologies.

The project is participating in Grid Catalyst initiatives and ongoing monitoring by the Center for Energy and Environment. Educational tours, open houses, and performance evaluations are planned to help building owners, engineers, contractors, and designers better understand the opportunities available in commercial retrofit projects.

The site will also serve as a demonstration project for EcoSnap technology and advanced ventilation strategies in small commercial buildings.

A successful end result

After a construction period of just 15 months, the result is an office building that offers a stable, comfortable indoor climate and is designed for an energy-efficient operation. This project shows how a combination of different climate ceiling solutions can achieve acoustic quality and ambitious sustainability targets.