The Province of Nova Scotia recently announced its intent to adopt the 2020 codes, including the National Energy Code of Canada for Buildings (NECB) 2020, effective April 1, 2025. As a tiered energy code, NECB 2020 is essentially four codes in one; the authority having jurisdiction can elect to adopt higher tiers over time, thereby progressing minimum energy performance without the need to introduce an entirely new code.

This article outlines the key changes and new compliance pathways (based on review of code changes and model results); the impact on design/construction practices in Nova Scotia as compared to current practices (based on both qualitative and quantitative evidence); and why you should care (based on the author’s perspective).

Key Changes to Minimum Performance Requirements for Building Systems

Tier 1 of NECB 2020 introduced several changes to the previous code (NECB 2017). Key revisions include:

• Thermal performance of above-ground envelope components: min. R value of opaque walls increased from R23 to R23.7; max. U value of fenestration decreased from 1.9 to 1.73
• Reductions in maximum lighting power density for most space types;
• Minimum efficiency of gas-fired boilers increased from 83% to 90%;
• Minimum efficiency of gas-fired domestic hot water heaters increased from 80% to 90%;
• Minimum efficiency of reference building heat pump systems (used in performance path compliance) increased from COP 3.1 to COP 3.3;
• Method of modelling air infiltration changed from 0.25 L/s/m² at 5 Pa to a building-specific calculation proportional to the ratio of total envelope area to above-grade wall area;

On average, the minimum performance required by NECB 2020 Tier 1 is roughly 5% more stringent than NECB 2017. This varies by project, depending on building type/size, system type, etc.

Notably, several key performance path/energy modelling requirements remain unchanged from NECB 2017.

These include:

• Effective thermal performance calculations must include the impact of all linear thermal transmittances in envelope assemblies;
• Reference building Fenestration and Door Area to Gross Wall Area Ratio (FDWR) remains 0.4 for HDD<4000;
• Energy recovery requirements:
  • Energy recovery is required for all continuously-operating ventilation systems except for self-contained ventilation systems serving a single dwelling unit in zones 4-6;
• Performance path reference building HVAC system is unchanged:
  • Reference system for any building with air- or ground-source heat pumps is a packaged unitary rooftop heat pump;
  • Reference heating system for gas-fired or electric resistance heating systems is as defined by applicable tables (boiler, furnace, or electric baseboards);

The energy recovery and reference HVAC system requirements in particular yield baseline/reference buildings with varying energy use intensities (EUIs) for any given building archetype, as the reference is defined based on the project-specific design elements. At the project level, this might mean that a high-performance design achieves a lower per cent improvement compared to a medium-performance design, due to a different reference HVAC system definition in the compliance analysis. With these code elements unchanged, this varying baseline scenario remains in place until at least 2030, or until a new version of the NECB is released.

Performance Tiers and Compliance Pathways

NECB 2020 will initially be adopted at Tier 1, with Tier 2 effective April 1, 2027 and Tier 3 effective April 1, 2029. The performance tiers are defined as follows:

• Tier 1: NECB 2020 baseline;
• Tier 2: min. 25% energy savings compared to Tier 1;
• Tier 3: min. 50% energy savings compared to Tier 1;
• Tier 4: min. 60% energy savings compared to Tier 1;

Tier 1 compliance can be achieved via prescriptive path or performance path (energy modelling). Tier 1 also defines the baseline/reference for the upper tiers. Tiers 2-4 require that projects achieve NECB compliance via performance path analysis. This means that all projects in Nova Scotia (excluding Part 9 buildings) will require code compliance energy modelling for building permit application, effective April 1, 2027. Under NECB 2017, some projects follow performance path compliance but some, especially smaller buildings, rely on prescriptive compliance.

Impact on New Buildings in Nova Scotia

NECB 2020 Tier 1 (April 2025) presents minimal change from current requirements. Projects applying via performance path compliance after April 1 will need to be modelled following NECB 2020 requirements; projects following prescriptive compliance will need to ensure the design meets the prescriptive requirements of NECB 2020. Therefore, identifying target dates for project permit applications will be important for design teams over Q4 ‘24 and Q1 ‘25.

Tier 2-25% savings (April 2027) will impact project design for some buildings. This performance is feasible using current design/construction practices, but projects will need to ensure energy performance analysis is conducted in early design staged to ensure compliance can be achieved.

Tier 3-50% savings (April 2029) represents a significant change from current design and construction practices. Most new buildings in Nova Scotia do not currently meet this performance. However, Tier 3 is feasible using current design approaches and technologies, if implemented in an optimized design approach. Integrated design teams and parametric energy modelling will be critical in the transition to this higher performance standard. Emerging technologies in mechanical equipment and envelope systems will likely also have a major role in achieving tier 3 performance.

Tier 4-60% savings has not been identified for adoption in Nova Scotia. This performance level would be challenging for many projects.

Why Should You Care?

The most significant energy performance impact of the new code is the requirement for Tier 3 performance as of April 2029. 4 ½ years may seem far off, but this is well within the planning timeline for many major projects in Nova Scotia; over the past few years, there have been several announcements of “mega-projects”, developments comprising several buildings and thousands of housing units to be constructed over phases of 5-10+ years. A large project entering conceptual design in 2025 may take several years to reach permit drawing stage.

Historically, achieving minimum energy performance standards required for building permit has been relatively easy, provided all applicable documentation is completed and submitted. Energy performance targets have typically not been at the center of design processes. Under Tier 3, energy efficiency will become a major design driver for new buildings. This will require a shift from traditional linear design processes, ideally leading to improved design team collaboration in an integrated design environment.

It is expected that future versions of the NECB will include carbon emissions targets, from both operational and embodied sources. NECB 2020 Tiers 2-3 will enable industry to transition toward an energy-centric design process, which in turn fosters industry readiness for carbon performance targets.

Anne’s final thoughts

Energy performance regulations have a critical role in climate change mitigation. We’ve seen and celebrated the announcements, the commitment and targets, from national, provincial, and local levels – X per cent reduction in emissions by Y year, etc. Stringent energy codes are a key element in achieving these commitments and reducing the climate impact of the built environment. It will require the industry to change; but change is needed, if we intend to achieve carbon reduction targets. The future code changes are challenging, and it won’t be easy – but if it were easy, it would already be done. Our province is fortunate to have an established precedent for innovation and change in building design; and a strong local industry dedicated to making buildings better. It’s an exciting time, folks.