As our team finalizes details of the mechanical plan for the Queen of Zero house, JLC’s Case Study 2024, I am reminded of the many unique challenges of designing an optimal heating, cooling and ventilation system for a really tight, high-performance home. I have also, over the years, gleaned some tips for builders to help facilitate a successful mechanical design process.
Mechanical Design Challenges
Homes aspiring to a Zero Energy Ready standard, such as the Queen of Zero, will achieve envelope air tightness of less than 2.0 ACH50— in other words, the home’s total volume of air will naturally ventilate less than twice per hour when subjected to 50 pascals of pressure through a blower door test. Passive house standards have traditionally required air infiltration performance of 0.6 ACH50 or less. Building mechanical systems to serve these types of high performing homes present significant design challenges.