HILLCREST VILLAGE

Northfield, MN 2020

Certified Passive House Consultant

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Image Credit Sweetgrass Design Studio

The City of Northfield is committed to 100% carbon-free electricity by 2030, and further, being a 100% carbon-free community by 2040. Their Climate Action Plan calls for community net-zero pilot projects. When the Community Action Center of Northfield (CAC) decided to embark on a new townhome development, board members saw it as an excellent opportunity to explore cost- effective approaches to net-zero. 

Precipitate collaborated with the Center for Sustainable Building Research to assess pathways to Net-Zero Energy for the affordable townhomes. The consultant project team worked collaboratively with owners, community members, design team, and contractor to model the anticipated energy consumption of the proposed designs in WUFI Passive. Precipitate compared three scenarios to achieve net zero: good (standard code-baseline construction), better (energy efficient construction), and best (passive house best practice). Precipitate shared best practices for design and construction with project stakeholders for major building systems, comparing standard practice to passive best practice. The wall assemblies at right show the iterative approach improved envelope.

Precipitate led workshops with the design team, including the contractor, to develop a hybrid solution taking elements from the best and better categories to develop a cost-optimized hybrid design that resulted in a high-performing building that would meet their budget. In the end, the hybrid option meets the requirements for PHIUS+ 2018 certification at an additional initial cost of about $10,000 per unit, or 4.3% of construction costs, which was the most cost-effective way to achieve net-zero. While the initial cost of the ‘good’ scenario would below, to meet the client’s goal of Net Zero it would require more solar panels than would fit on the project site and have higher operational maintenance costs over higher performing options.

High Performance Elements

  • Compact Massing

  • Triple-pane windows

  • R40+ walls and R60+ roof

  • Air-tight construction

  • Heat recovery

  • Cold climate heat pump

Collaborators

Lessons Learned

  • We have powerful tools to employ building science to achieve cost-effective, net zero-ready construction

  • Coordination and integrative process overcomes paralysis when diverting from standard design processes that have been followed for decades

  • Current standard practices can lead to dangerous moisture and durability issues that are currently ignored

  • Standard energy models are a blunt tool primarily for equipment sizing, not modeling critical components like air infiltration and thermal bridging for envelope design

  • Passive House can be achieved affordably in cold climates like 6A where this project is located