# Calculating energy use intensity for the clean buildings tax credit

Publication date: January 26, 2023

As part of the certification process for the clean buildings tax credit, a qualified person must provide and confirm the required energy use intensity (EUI) calculation results of the eligible building. They must also confirm that the retrofit reduced the EUI of the building and met the targets.

## Qualified persons

For the purpose of providing and confirming the required energy use intensity calculation results for a clean buildings tax credit certification, a “qualified person” includes:

• An architect
• A professional engineer
• A qualified energy advisor certified by Natural Resource Canada and employed by or under contract with a service organization licensed by Natural Resources Canada to perform EnerGuide Rating System evaluations

## Understanding energy use intensity

A building’s energy use intensity (EUI) is the net energy used by the building divided by the building’s floor area.

To qualify for the clean buildings tax credit, a retrofit must reduce the EUI of the building to a value lower than:

• What it was before the retrofit, and
• The target EUI for the type of building

A building’s target EUI depends on the:

• Location of the building
• Type of building, and
• Hours the building is operating in an ordinary week

## Calculating a building’s energy use intensity for a year

To calculate the energy use intensity (EUI) for a building for the purpose of the clean buildings tax credit, you need to first determine:

1. The net energy of the building for the year, expressed as megajoules, and
2. The floor area of the building, expressed in square meters

Net energy of the building for the year is the total of metered energy that entered the building during the year and bulk fuel used by the building in the year, less any metered energy that left the building.

Bulk fuel use may be calculated by:

• Measuring existing inventories at the beginning of the year
• Subtracting final inventories at the end of the year

To determine the amount of energy used, you may use these prescribed energy value conversion factors:

Prescribed energy value conversion factors

Prescribed energy value conversion factors
Bulk fuel Energy
Fuel oil #1 37.6 MJ/L
Fuel oil #2 38.7 MJ/L
Fuel oil #4 40.7 MJ/L
Fuel oil #5L 41.3 MJ/L
Fuel oil #5H 41.8 MJ/L
Fuel oil #6 42.9 MJ/L
Natural gas 38.4 MJ/L
Propane 25.5 MJ/L
Electricity 3.6 MJ/kWh

The floor area of the building is measured from the exterior faces of exterior walls and from the centreline of walls between buildings. Specific measurement requirements exist for multiple unit residential buildings and other buildings:

Calculating floor area of multiple unit residential buildings

The floor area of a multiple unit residential building is the total of the floor areas of all the conditioned spaces in the building, including:

• Conditioned garages
• Conditioned basements
• Conditioned attics

Conditioned space means a space that is provided with heating or cooling capable of maintaining the temperature of the space between 10oC and 30oC.

The floor area of a multiple unit residential building does not include:

• Crawl spaces
• Covered walkways
• Open roofed-over areas
• Exterior terraces or steps
• Roof overhangs

Calculating floor area of other buildings

To measure the total of the floor areas of any other building, include in your calculation all the spaces within the building except:

• Covered walkways
• Open roofed-over areas
• Porches and similar spaces
• Pipe trenches
• Exterior terraces or steps
• Roof over-hangs
• Parking garages
• Surface parking or similar features

Do not include deductions for holes in the floor other than atria.

Once the above is determined, you can calculate the EUI for a building for a year as:

EUI for a building for the year (MJ/m2) = Net energy of the building for the year / Floor area of the building

## Calculating the target energy use intensity

The target EUI is calculated by multiplying the base EUI target of the building type (see Table 2 below) by an operating hours multiplier (see Table 3 below):

Target EUI (MJ/m2) = Base EUI target of building type x Operating hours multiplier

To make this calculation, you need to know the:

1. Climate zone the building is in
2. Building type, and
3. Operating hours of the building in an ordinary week

Climate zone is determined by the heating degree days below 18oC at the location of the building being retrofitted. The heating degree days must be determined using the 10-year average of climatic data from the weather station most representative of the location of the building or, if 10 years are not available from that weather station, based on climatic data most representative of the location of the building.

Table 1: Climate zone by annual heating degree days below 18oC
Annual heating degree days Climate zone
3,000 HDD or less Zone 4
Between 3,000 HDD and 4,000 HDD Zone 5
4,000 HDD or more Zone 6

You can find local information on heating degree days through:

The climate zone and building type allow you to determine the base EUI target of the building needed for the calculation:

Table 2: Base EUI targets by climate zone for different building types
Building type Climate zone 4 Climate zone 5 Climate zone 6
Multiple unit residential building - 3 or fewer stories 573 550 749
Multiple unit residential building - 4 or more stories 644 658 842
Accommodation 902 923 1046
Colleges and universities 1003 1034 1420
Food services 2345 2328 3002
Hospitals 1787 2032 2919
Logistics and warehouses 470 505 710
Long term care 887 922 1272
Offices 678 720 864
Retail - food 1584 1555 1886
Retail - other 635 671 728
Schools 553 578 835
Other buildings 595 638 734

The multiplier needed for the calculation is based on the operating hours, which refers to how many hours the building is in operation in a typical week. Lookup the multiplier for the building in table 3 below.

If your building has parts that are different types, you must determine a prorated energy target by calculating the target EUI for each part of the building and multiplying that target by the percent of floor space used for each type.

If your building, or part of your building, is used for different purposes at different times, the building or part must be considered for determining the EUI target as belonging to the type of primary use.

Table 3: Operating hours multiplier for different building types
Building type 50 hours or less More than 50 but less than 168 hours 168 hours or more
Multiple unit residential building - 3 or fewer stories 1.0 1.0 1.0
Multiple unit residential building - 4 or more stories 1.0 1.0 1.0
Accommodation 1.0 1.0 1.0
Colleges and universities 1.0 1.0 1.2
Food services 0.8 1.0 1.2
Hospitals 1.0 1.0 1.0
Logistics and warehouses 1.2 1.3 1.3
Long term care 1.0 1.0 1.0
Offices 0.9 0.9 1.2
Retail - food 1.0 1.0 1.4
Retail - other 0.7 1.1 1.5
Schools 1.0 1.0 1.2
Other buildings 0.8 1.0 1.2