TEUI B.1 Major Occupancy

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Of the 50+ user-inputs in the TEUI3 calculator, B.1 Major Occupancy mirrors the Occupancy types as set out in both the National and Provincial Building Codes of Canada. When a Major Occupancy is selected, a number of variables come into play. Here are the options for Major Occupancy:

• A – Assembly
• B1 – Detention
• B2 – Care and Treatment
• B3 – Detention, Care and Treatment
• C – Residential
• D – Business and Personal Services
• E – Mercantile
• F – Industrial

By selecting the appropriate Occupancy type, six distinct functions are determined namely;

• Temperature limits, Occupancy-dependent Cooling and Heating Temperature Setpoints (see table below, ie. 18ºC or 22ºC for Heating, 24ºC for Cooling, the latter being a new addition to the 2025NECB/NBC, where 26ºC is a new absolute limit proposed for the 2020 cycle: https://cbhcc-cchcc.ca/eng/public-review/2024_2/pcfs/nbc20_divb_01.01.03.01._002061.html)
• DHW or SHW Use – based in litres per person per day, this Domestic Hot Water Use is set at 275 l/pp-day for C Residential Occupancies – but must be defined by an engineer for all other uses. This 275 l/pp-day used by TEUI3 is a mix of Hot and Cold water use, where the NBC assumes 97 l/per day per household [Table NBC 9.36.5.8] is 100% hot water use at a delivery temperature of 55ºC.
• Plug Loads, the total loads from occupant devices that generally are not hard-wired into a building’s electrical system, computers and blenders and toasters belong to this group. For some background research on this, and why these are lower than formerly assumed, see NREL’s report here: https://www.nrel.gov/docs/fy14osti/60266.pdf
• Lighting Loads, generally fixed loads, hardwired into the building, and having a known load profile and schedule or ‘Lighting Power Density’ or LPD in W/m² (refer to NECB Table 4.2.1.5).
• Equipment Loads, heavy equipment such as pumps, fans, compressors, elevators and the like, hardwired, but generally functioning during the same schedules as other loads (ie. an office that is unoccupied at night, less LPD load, less plug loads, less Equipment Loads.
• Typical Schedules (Defined in both NBC, NECB, SB10, SB12 and ASHRAE, but simplified in TEUI3). TEUI3 sets all occupancy usage at 12hrs/day or 4380hrs/yr, or 50% of all annual hours, with Occupants adding 117 W/pp of combined sensible and latent load to the space as a default.

In TEUI3 these appear as:

• B1.1 Thermostat Setpoint Heating (per Occupancy)
• B1.2 Thermostat Setpoint Cooling (per Occupancy, but for All Types per NBC 2025)
• P.1 Scheduled Hours Occupancy/yr.(per Occupancy, but loosely defined in TEUI3, these can be refined or expanded by the user)
• P.2 Plug Loads, set at 5W/m² for Residential uses and 7W/m² for all others.
• P.3 Lighting Power Density: 1.5W/m² set for all occupancies – these were formally much higher, but with LED lighting, LPDs have dropped substantially
• P.4 Equipment Loads, by Occupancy, and we are trying to find some established baselines for defined building typologies
• P.5 Exterior Site Loads, stuff like sprinkler systems, exterior lighting, ice-melting systems or equipment that is external to the building but still shows as a metered load.

These Occupancy-driven presets establish a baseline for common occupant behaviour within a space during defined durations and times of day. For the sake of simplicity, TEUI3 generates these presets from the selected Occupancy, but these can be over-ridden by the user (architect or engineer) on the ‘Schedules’ worksheet. For example, let’s take a Residential Occupancy, C. In a Part 9 Single Family Home, or in any unit of housing, establishing a baseline of 2 adults, 2 children, present in the space 50% of the time has long been considered a way to set a usage pattern that covers a ‘conservative’ scenario, while preventing ‘gaming’ of energy models by allowing unique scenarios such as; one adult, one teenager, at home 90% of the time. The 2 adults accounts for 2 adult metabolic rates, and 2 kids with 2 kid’s worth of metabolism, since occupants generate thermal energy, but also use appliances and lights.

The preset for 50% of the time Occupied can be defined as 4380 of 8760 total hours in a year. This makes it easy to define loads in terms of hours used and Watts used, like Watt-hours Wh and kilowatt hours kWh (multiply or divide by 1,000 to go from one to the other). So a 100m² dwelling with a LPD of 1.5W/m² would have a load of 100*1.5*4380/1000 = 650kWh/yr. It should be noted that most energy uses inside a building do useful work, like illuminating a dining table, making toast, or boiling water, but these also generate heat, and so the energy use converts to an energy gain, which partially offsets heating loads. More on Net-Useable Gains later, but for now, just know that all loads defined by occupancies within a space, also generally convert to gains within the same occupancy.

The Minimum Indoor Temp °C as per OBC 6.2.1.2, otherwise known as the Temperature Set-point for Heating, or Tset. Here’s what the full table looks like from TEUI3’s ‘Design Temps and Schedules’ worksheet. Historically the building codes only really concerned themselves with occupant comfort in the heating season. It’s not a requirement to provide cooling, but with other guidelines when cooling is provided, then cooling setpoints are determined by those standards, such as ASHRAE 90.1. To our knowledge of the draft 2025 NBC/NECB is set to withdraw support for ASHRAE 90.1, and cooling targets will soon be established for critical occupancies, as a result of the increasing frequency of building overheating, a warming climate, and general cooling system design inadequacy. For example, ASHRAE permits temperature values as high as 26ºC as a Tset for cooling, where the proposed NBC reduces this to 24ºC.

Occupancy Type	Min. Indoor Temp °C as per OBC 6.2.1.2	Max. Indoor Temp °C as per NBC 2025  (ref. pending)	Critical Occupancies (apply 1% Coldest Temp)
A – Assembly	18	24	N
B1 – Detention	18	24	N
B2 – Care and Treatment	22	24	Y
B3 – Detention, Care and Treatment	22	24	Y
C – Residential	22	24	N
D – Business and Personal Services	18	24	N
E – Mercantile	18	24	N
F – Industrial	18	24	N

Of course thermal comfort is a much more complex subject than just temperature, as humidity, clothing level, air movement, Radiant Mean Temperature or RMT (how warm or cool your surroundings feel), light hue or temperature – all play a role, but we are only really considering a simplified approach to energy and carbon with TEUI3. When high-performance targets are met, often these complex comfort metrics start to align as well. A building that is neither too hot or too cold generally has a more comfortable RMT, and a building that ventilates well often has an airtight, draft-free construction as well.

If you are modelling a large building with multiple or mixed Occupancies, it’s a good idea to parse these out as separate buildings – each Occupancy can have its own TEUI3 worksbook, and you can just sum the totals together if you want to account for all loads.

In closing, when you select a Major Occupancy in TEUI3, just know that it establishes a number of preset values that attempt to align with NECB, NBC, OBC and good design practices, without becoming too complicated, and without facilitating gaming of the model.

Reference: https://cbhcc-cchcc.ca/eng/public-review/2024_2/pcfs/nbc20_divb_01.01.03.01._002061.html (26ºC Max. in at least one room of any C Occupancy).