Net-zero-ready in Ottawa

Project Description

Planning the Retrofit

The retrofit project was not originally intended to achieve net zero energy performance. However, as the design and construction progressed, the homeowner made significant personal investments, including enhancements to the basement that were not part of the initial plan. The scope of the project expanded to include every exterior component of the home, which naturally led to deeper considerations around energy efficiency. Central to the retrofit were themes of accessibility and adaptability, driven by the understanding that life circumstances can change unexpectedly, and making such modifications later could be both challenging and costly.

Getting to Net Zero

Reaching net zero was not an intentional goal at the outset of the project, but it became a natural outcome due to the comprehensive nature of the retrofit. By addressing every wall and exterior component, the project inherently improved the home’s energy performance. A key step in this transformation was the shift from natural gas to electric systems, which played a crucial role in reducing greenhouse gas emissions and aligning the energy use of the home with a cleaner electrical grid. Solar Panels are also going to be installed after the retrofit.

Lessons Learned

The retrofit process revealed several important lessons. One notable insight came from a section of the house that retained its original Typar air/weather barrier. During air pressure testing, the barrier began to billow, clearly indicating air leakage and highlighting the limitations of relying on existing materials. This led to a deeper understanding of air barrier strategy, prompting the team to move away from patching weak spots and instead adopt ZIP panels and continuous insulation to create a more effective building envelope. Another key learning involved the mechanical system design: the original forced-air system struggled to meet demand, whereas the post-retrofit system now maintains consistent comfort without the need for manual adjustments. Additionally, the team recognized the critical importance of air barrier continuity at transition points. They discovered that airtightness and thermal performance depend not only on the connections between exterior and interior walls but also on interior load-bearing walls that intersect with the air barrier system and areas that are often overlooked but essential for maintaining envelope integrity.