Elizabeth was honored to present What to Expect when pursuing Passive House at the Twelfth Annual MN ASHRAE/AEE Energy Expo along with Chloe Bendistis of The Sheward Partnership. They shared two case studies of projects that had pursued PHIUS+ 2015 certification. Chloe was sustainability consultant for The Goddard School, a preschool in Pennsylvania, and Elizabeth was the Certified Passive House Consultant for Hook & Ladder, a 59-unit affordable housing building in Minneapolis.
Tips for successful large-scale PHIUS+ projects
Based on their experience with these case studies, Elizabeth and Chloe shared lessons learned and project tips for engineers working on PHIUS+ buildings of similar scale and scope. Originally used with single family residential projects, PHIUS+ is quickly gaining popularity for use with multi-family projects as well as commercial. Here are some items to keep in mind when working with larger buildings:
The larger the building, the lower the ratio of envelope square feet to square feet of interior conditioned floor area (iCFA), and the greater the impact mechanical system design and internal loads will have on the ability to become PHIUS+ certified.
Therefore, we can't meet the criteria with a focus on exterior envelope alone - collaboration is critical for larger buildings in particular. Meet early and often with the whole team to discuss the impact of mechanical systems and internal loads from the very beginning.
Brainstorming sessions with the CPHC and mechanical engineer can be incredibly useful in developing strategies to bring back to the larger team.
Work with the architect to avoid excessive square feet per person.
Consider which rooms need to be 'inside the building envelope.' If they don't need to be heated/cooled/ventilated, don't include them. Perhaps semi-conditioned spaces with electric heat to prevent freezing is sufficient.
Determine a process for gathering performance data from mechanical systems. These will be critical components of the certification process and often manufacturers don't have this data readily available. Plan ahead.
Multiple energy models will be necessary for multiple purposes. WUFI Passive is necessary for receiving PHIUS+ certification and optimizing the building envelope, but cannot be used to size equipment or meet code.
Feel free to be innovative! If there's something you know will save energy but you're not able to model, submit a rationale to the PHIUS Technical Committee for review.
A photovoltaic system will likely be necessary in multifamily housing projects to meet per-person source energy targets.