Ask the Expert: Nerva Energy Group

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Member Profiles

With a focus on driving energy conservation and positive financial outcomes, Nerva Energy Group offers expertise in energy performance solutions to maximize buildings’ energy efficiency and financial savings. Winner of the Green Building Visionary award in 2023, Nerva Energy Group is famous for AeroBarrier, an innovative interior-applied envelope-sealing technology that changed how buildings can reduce their heating and cooling energy needs by improving indoor air quality and reducing GHG emissions. Josh Lewis, VP Energy Engineering at Nerva Energy Group tells us more about how their product came to be and how it can help projects reach their sustainability goals.


Tell us about your Toronto-based multi-residential building pilot, how this pilot came about, and what it hopes to accomplish.

“Airtightness” is not a term that comes up often when discussing the merits of a building, but for industry experts and building science professionals, air infiltration (i.e. the unintentional introduction of outside air or the loss of indoor air, typically through gaps in the building envelope and mechanical perforations) is actually a huge factor in energy efficiency, accounting for up to 30% or more of a building’s heating and cooling costs, according to the CMHC.

A recent new construction project developed by Collecdev set out to prove the merits of airtightness in multi-residential buildings.

The goal was to evaluate the impact that aerosolized sealing could have on the building’s final airtightness performance.

What developers have come to learn is that it is almost impossible to build an airtight building through conventional methods – there are just too many construction trades involved in each project. Whether it be windows, electrical, plumbing, or mechanical, these installations often create unintentional leaks in the envelope.

The results from Tippett Park project show the following KPIs:

  • Suite-level air leakage rates with the aerosolized sealant were 27% lower than conventional.*
  • Suite level ACH improvement of 47.4%
  • Suite level CFM improvement of 47.3% (@50pa)
  • TEDI reduction of 8% without ventilation, and 19.2% with ventilation
  • Achieved a whole building airtightness test result of 1.31 L/S-m2 @ 75pa without any other airtightness measures being implemented. The default value for energy modelling under the Toronto Green Standard is 2.00 L/S-m2, which makes this building 34.5% more airtight.
Could you elaborate on the role airtightness plays in delivering high performance buildings?

Industry experts agree that leaky buildings have a negative impact on HVAC performance, energy consumption, greenhouse gas emissions, indoor air quality, comfort, and well-being. Improving the airtightness of the building envelope not only leads to healthier communities and a smaller environmental footprint, but it is also essential for meeting the mandatory energy targets set by individual bodies, such as the Toronto Green Standard (TGS), the above-code standard set by the City of Toronto.

Any outside air that infiltrates through the envelope can lead to condensation and moisture issues – compromising the structural integrity of the building – while indoor air that escapes the envelope has a significant impact on heating and cooling requirements. Conditioned air that leaks out of the building through openings in ceilings, walls, and floors, as well as mechanical penetrations, ultimately causes unnecessary energy and carbon waste.

In order to build a high-performance building, we must push beyond traditional construction practices. When you look at the highest industry standards for energy and carbon efficiency, all roads lead to maximizing the building’s level of airtightness. An airtight building envelope is key to achieving these high standards.

Ultimately, airtightness provides a path to potentially reducing costs, as the additional investment in aerosolized sealing can be offset by the reduced size of the mechanical systems needed to heat and cool the building, as well as operational savings throughout the building’s entire life.


What makes AeroBarrier, the air sealing system Nerva Energy Group developed, a unique product and what effect has it had on green building?

AeroBarrier technology is a general-purpose system that seals holes as large as 5/8 of an inch, all the way down to holes not visible to the human eye – those as small as a hair follicle.

This patented technology is connected via a modified blower door to pressurize and distribute the sealing formula into the space. The pressure carries a non-toxic, water-based formula throughout the space and effectively seals any leak by using the very air that is leaking out of the room, thereby finding any leak point; visible or not.

Aerobarrier not only significantly lowers energy consumption for a building, resulting in operational savings, environmental benefits, and optimized HVAC function, but also improves air quality and reduces the spread of airborne disease, resulting in big benefits like:

  • Up to a 98% reduction in air leakage
  • Greatly reduced risk during construction of meeting the airtightness target
  • Significant reductions in mechanical plant sizing
  • Lower utility bills (up to 30%)
  • Better indoor air quality
  • Reduced transfer of odours
  • Better performance for HVAC systems
  • Improved soundproofing
  • Protection against insects and pests
What do you see are the key issues / opportunities facing the industry with regards to sustainability?

As we grapple with global warming, energy shortages, urban sprawl, and other interconnected challenges, it becomes clear that sustainable development isn’t optional; it’s imperative. The stakes are too high for us to ignore the calls for energy-conscious practices. Failure to embrace sustainability will not only exacerbate these issues, but will also leave a troubled legacy for future generations. Sustainability isn’t a buzzword—it’s an urgent necessity.

Design-phase decisions greatly impact a building’s life-cycle efficiency. Common issues like poor airtightness and oversized equipment significantly escalate build costs.

The ‘building as a system’ approach demands an understanding of the intricate relationships between its various components like the building enclosure, inhabitants, mechanical/electrical systems, site & services infrastructure, and external environment. This systemic view ensures the building performs optimally as a whole, promoting interdisciplinary design and planning, that ultimately culminates in efficient, high-performing buildings.

The biggest opportunity that the industry has, beyond ensuring that all buildings are built or retrofitted to be airtight, is to move away from the “Design, Bid, Build” methodology and instead adopt “Integrated Design and Delivery” which is proven to align the entire development, design, and construction team on a project to deliver the highest performing building at the lowest possible cost.


Nerva Energy Group Inc. was named Green Building Visionary as part of CAGBC’s 2023 Leadership and Green Building Excellence Awards. What does it mean to your organization to be recognized in this way?

We have immense admiration for CAGBC. We are humbled and honoured to receive this prestigious recognition. It stands testament to our unwavering commitment, innovation, and the cohesive efforts of our passionate team. We’ve consistently strived to set new standards in energy conservation, and this accolade shines a spotlight on our achievements.

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