Understanding Tiered Energy Efficiency Requirements (PDF)

The idea of tiered codes is still somewhat new in Canada. All future energy efficiency requirements are published in the code up front, leading from a base code to the most ambitious energy efficiency goal. Tiered Codes provide a road map to builders, manufacturers, and provincial governments, resulting in consistent application across Canada at each level. 

Updates in the 2025 Codes

While the 2020 National Building Code of Canada (NBC) introduced the tiered energy code concept, the 2025 edition of the NBC provides builders and designers with more flexibility compared to the 2020 Codes, so that builders trying to comply with the higher tiers using the 2020 national codes can use them as guidance.

For example, the 2025 NBC now includes prescriptive requirements for all five energy tiers (Tiers 1 to 5) and even includes two prescriptive options: the prescriptive trade-off path (Subsection 9.36.8.) and tiered energy prescriptive packages (Subsection 9.36.9.). Of course, modelling a home’s  energy performance is still possible using the performance path (Subsection 9.36.7.).

Caution: Tier 5 requires a 70% overall energy use reduction and is the most ambitious target in the NBC.  Netzero Homes labelled under CHBA’s own Net Zero Home Labelling Program show that it is not necessary to build a tier 5 home to reach Net Zero Energy Ready performance. Instead, a 60% total energy use reduction can produce Net Zero Energy Ready Homes in all climate zones, which is important when one considers that, on average, Tier 5 construction may have three times the incremental construction cost compared to Tier 4 (40% energy use reduction).

Compliance Methods

The NBC 2025 offers three main compliance options under Section 9.36:

• Performance Path (Subsection 9.36.7.) – An energy advisor models the proposed home and compares it to a reference home. This is the most flexible option and offers the potential of the most cost-effective path.
• Energy Use Intensity Metric (Subsection 9.36.8) – This method creates an energy budget for a proposed home design, based on a home’s size and (compact) geometry.
• Prescriptive Trade-Off Path (Subsection 9.36.9.) – This path provides a flexible mix-and-match points method to reach the minimum points required for each tier. This is the most flexible prescriptive path.
• Prescriptive Packages (Subsection 9.36.10. to 9.36.14) – this path provides recipe-like, look-up tables (builder option package) for each tier. This path is straightforward but provides the least amount of flexibility and it is not cost-optimized.

A Word on Airtightness Testing

Airtightness is the most critical building science principle to get right in a home, especially as we move into higher energy performance tiers (4 and 5). The most reliable way to ensure airtightness is achieved is through blower door testing. However, mandating airtightness testing in building codes presents challenges as energy advisors (EAs) typically conduct these tests, and their limited availability in many regions can cause delays and increase costs. Plus, EAs are not involved when builders follow the prescriptive path, e.g. the trade-off points method.

To make airtightness testing more accessible and practical, we need a dedicated technician designation or trade – an “air boss” – who can perform blower door tests in front of building officials for code compliance.

This need is underscored by how the Subsection 9.36.6 sets the default airtightness rate for energy modelling of the proposed house to 3.2 ACH (air changes per hour), up from the previously assumed 2.5 ACH in the 2015 edition. This change affects builders using the performance path for energy compliance. Builders who do not conduct airtightness testing will now be subject to the less favourable 3.2 ACH default, and their homes will require compensatory upgrades to the building envelope or HVAC systems because the 3.2 ACH is being compared to a reference house model with 2.5 ACH. The option to use the 2.5 ACH rate also for the proposed house being modelled remains only for those who perform airtightness testing. This shift effectively incentivizes testing, though it has not been mandated, and may disadvantage smaller builders or those in remote areas where testing is impractical. 

Performance Path (Subsection 9.36.7.)

To meet a tier through the performance path, an Energy Advisor or a qualified professional carries out energy modelling, and the proposed house is compared to a standardized (reference) house model simulated “built” according to prescriptive requirements in tier 1.

Technical Concepts

The performance of the proposed home is measured by three main requirements:

• Energy Improvement – The house must use less energy for heating, cooling, ventilation and hot water combined than the reference house does. Each tier specifies a target percentage less than. The code refers to this as ”percent improvement” or “percent house energy target”
• Envelope Improvement – The house must lose less energy to the outside than the reference house does. Each tier specifies a target percentage for this reduction. The code refers to this as “percent heat loss reduction”.
• Peak Cooling – Proof is required that the proposed house is not more likely to overheat than the reference house. (The method used in the 2020 codes to demonstrate compliance for this metric may be problematic. See CHBA’s backgrounder on the topic).

Table 9.36.7.2. (a summary is shown below) contains the main targets for the envelope and total energy improvement metrics for each tier. The table also lists relaxations for very small houses.

Energy Use Intensity Metric (Subsection 9.36.8)

This new method is a simplified performance path that – instead of modeling a reference house – sets target budgets for a home to demonstrate compliance, which are based on a home’s size (heated floor area) and heating degree days (HDD). The proposed house metrics for total energy use and total heat loss come from an energy model that complies with Subsection 9.36.5.

The proposed house gets compared against these three main target budgets:

• Annual gross heat loss target budget (insulation, airtightness, ventilation heat loss)
• Design cooling load budget (heated floor area multiplied by 15 W/m²)
• Annual energy consumption target budget (heated floor area multiplied by a local energy use factor minus 6500)

If the proposed design stays below the target budgets, the home meets the requirements. Higher tiers mean tighter budgets, but the process is the same.

Technical Concepts:

• The Local Energy Use Factor and the Local Heat Loss Factor are both based on a home’s size (heated floor area) and heating degree days (HDD). Both factors are used as input into the respective energy use and heat loss budgets.
• Annual Energy Consumption Target Budget (used in this method instead of the Reference House model) is a fixed energy consumption limit reported in kWh/a
• Annual Gross Space Heat Loss Target Budget (used in this method instead of the Reference House model) is a fixed envelope and ventilation heat loss limit reported in kWh
• Design Cooling Load is calculated using the standard procedure of CSA F280 “Determining the required capacity of residential space heating and cooling appliances”
• Design Cooling Load Budget is calculated by multiplying the heated floor area by 15 W/m²
• Tier Adjustment Factors are percentage reductions when calculating the target budgets for different tiers. Note that the factors for adjusting annual energy consumption and annual heat loss are different 

Step-by-step instructions for using the EUI compliance path

Collect/Calculate the Inputs:

• Determine the Heating Degree Days (HDD) and the heated floor area (in m²)
• Calculate the Local Energy Use Factor by multiplying the HDD by 0.02 and subtracting 12.3 from it
• Calculate the Local Heat Loss Factor by multiplying the HDD by 0.02 and adding 32.6 to it
• Calculate the Annual Energy Consumption Target Budget by multiplying the heated floor area with a local energy use factor and adding 6500. For homes with less than 115m² heated floor area, use 115m² (giving you a credit), for homes with more than 350m² heated floor area, use 350m² (making the budgets more stringent)
• Calculate the Annual Gross Space Heat Loss Target Budget by multiplying the heated floor area with a local heat loss factor. For homes with less than 115m² heated floor area, use 115m² (giving you a credit), for homes with more than 350m² heated floor area, use 350m² (making the budgets more stringent)
• Calculate the target budgets for the desired tiers by multiplying the respective budgets with the correct Tier Adjustment Factors (Note that the adjustment factors for heat loss and energy use are different!)
• Calculate the Design Cooling Load using the CSA F280 calculation and multiply it by 1.1, or use a 15 W/m² cooling intensity to multiply with the conditioned floor area, or simply install mechanical cooling to meet the requirements.
• Obtain the Total Energy Use and Gross Heat Loss values from your proposed house model

Compliance Check:

• Homes with a design cooling load
  greater than the design cooling load budget shall be equipped with mechanical cooling
• Compare the budgets with the proposed house modelling data: Proposed homes comply if
• the Annual Energy Use (from the model) is smaller than
  the Annual Energy Consumption Target Budget
• the Annual Gross Space Heat Loss is smaller than
  the Annual Gross Space Heat Loss Target Budget

Prescriptive Trade-Off Path (“Points Method”) (Subsection 9.36.9.)

The 2020 NBC maintains the base case prescriptive “package” (Subsections 9.36.2.-9.36.4.) from the 2015 NBC but introduced the trade-off points method for Tiers 1 and 2 with a limited set of Energy Conservation Measures (ECMs). The 2025 NBC will complete the trade-off compliance options in Subsection 9.36.8.

Technical Concepts:

• Target Energy Performance –each energy tier has a set minimum value of points that need to be reached by a home to comply with that tier.
• Energy Conservation Measures (ECMs) – specific upgrades or design choices that improve a building’s energy efficiency, for example, better insulation, high-performance windows, efficient heating systems, or improved airtightness that have a point value.
• Energy Conservation Points (ECPs) – are the values representing the energy-saving impact of specific building upgrades (known as Energy Conservation Measures (ECMs)). The more impactful the ECM is in saving energy, the more points (ECPs) it earns. The total number of points for a home design determines whether it meets the energy efficiency requirements for a given Tier (e.g., 40 points to comply with Tier 4). It is important to note that a code user can use interpolation when selecting ECMs and ECPs.
• Building Envelope Backstop – the required total value of ECPs for each tier is linked to a minimum amount of ECPs that have to come from building envelope measures. This ensures good practice in energy efficiency design by maximizing envelope upgrades before improving equipment efficiencies.
• Building Volume Relaxation – the total volume of conditioned space is also a factor. Homes having a volume less than 390m³ can obtain up to 10 energy conservation points (ECPs), which acknowledges that small homes are inherently more energy efficient.

How to use the prescriptive trade-off path

Builders can determine the necessary Energy Conservation Measures (ECMs) to earn the minimum required Energy Conservation Points (ECPs) for the desired energy tier. While minimum required tiers may be set by provincial building authorities, builders can voluntarily meet higher tiers than those minimum tiers.

2025 NBC Table 9.36.8.2.B shows the required ECP totals per Tier, and Table 2 lists ECMs with point values, which vary by climate zone, airtightness, insulation, window type, and equipment efficiency. This flexible approach lets builders mix and match ECMs to find cost-effective solutions that meet their project’s required tier.

Step-by-step instructions for the Prescriptive Trade-Off Path

• In Table 1, select the Climate Zone you are building in and the tier you are targeting
• Select Energy Conservation Measures (ECMs) (from various code tables) that apply to your design including building envelope-related measures
• Calculate the total of the respective Energy Conservation Points (ECPs) for your selected Energy Conservation Measures (ECMs), keeping a tab on the building envelope measures.
• Compare the required value of ECPs for the desired tier in Table 1 with the total ECPs for your design, ensuring the required envelope points are met

Note: Compliance examples and blank template for this process are provided at the end of the. 

Prescriptive “Packages” (Subsection 9.36.10-14. – 2025 NBC)

This compliance path allows builders and designers to find all requirements for the building envelope and HVAC options in one place. It is the simplest to follow but is the least cost-effective when compared to the trade-off points (9.36.9.) or the performance path (9.36.7.). The 2020 NBC only has a prescriptive package for tier 1 – the base code, while the 2025 NBC has prescriptive packages for tiers 1 and 5. Some Subsections are reserved for adding future packages for tiers 2, 3 and 4 in the 2030 NBC.

Technical concepts

• Fuel Options for HVAC Equipment – two different tables require different metrics for HVAC equipment based on whether the home is heated with ‘dual energy’ (oil or gas /electric heat pump) or an electrically operated heat pump and electrical resistance heating as backup.
• Building Volume Relaxation – the total volume of conditioned space is also a factor in the tier 5 package. Homes having a conditioned volume less than 300m³ can use a different look-up table for above-grade and below-grade assemblies with lower RSI value requirements.

Step-by-step instructions for using Prescriptive Packages

• Calculate the volume of the conditioned space in your proposed design and determine whether it is less than or equal to 300m³ or greater than 300m³
• Select the fuel type for heating equipment - either all electric or dual energy (electric with gas or oil for supplemental heating)
• Find the appropriate provisions and tables based on volume and fuel (applicable to tier 5 only) for the energy tier you are targeting (currently, only tier 1 and tier 5 are available)
• Use the values in the corresponding column for your climate zone 

APPENDIX

Examples – Prescriptive Trade-Off Path

The examples illustrate how the method works and showcase progressive design changes to Energy Conservation Measures (ECMs) that show the impact of the Energy Conservation Points (ECPs) for compliance. The information for the examples below was taken from multiple 2025 NBC Tables in Subsection 9.36.9.

Caution: To get any ECPs for airtightness, a blower door test is required. The code does not specify who can do this test. Therefore builders could offer testing in in the presence of a building official. 

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