This paper documents part of the candidate's Ph.D. research into the use of earth tube systems as a method for improving energy efficiency, indoor air quality, and whether mechanical cooling systems can be eliminated. Climate change reality in Canada in combination with stricter energy codes forces the architectural and engineering professions to embrace new design considerations. Traditionally heating energy has been the most significant energy use across Canadian climate zones, but with climate change and enhanced envelopes, the cooling energy is increasing. This paper will explore how passive cooling approaches including earth tubes and hybrid ventilation systems would operate as a means of reducing energy use, low-carbon comfortable buildings. The building type described in this paper is commercial office for a public sector client who is the owner-occupier. The proposed passive cooling methods are harnessed to enhance overall occupant wellness and energy performance are evaluated and compared to traditional mechanical building services systems and design methods with a view of re-assigning budgets to achieve maximum benefit. The paper will provide a focus on earth tube systems—how they work, particular design considerations—and a performance review of an installation on a commercial office building in Kelowna, British Columbia, Canada. The discussion will review methods to incorporate earth tube systems and other passive cooling techniques—and present budget estimates, energy savings, and paybacks.