| Acronym | Abbreviation |
| AAHP | Air-to-air heat pump |
| AC | Air conditioner |
| AHU | Air handling unit |
| ASHRAE | American Society of Heating, Refrigerating and Air-Conditioning Engineers |
| AWHP | Air-to-water heat pump |
| BEM | Building energy model |
| BTAP | Building Technology Assessment Platform |
| CAV | Constant air volume |
| COP | Coefficient of performance |
| DOE | Department of Energy |
| DX | Exchanger |
| ECM | Energy conservation measures |
| FCU | Fan coil unit |
| GSHP | Ground source heat pump |
| HP | Heat pump |
| HVAC | Heating, ventilation and air conditioning |
| MURB | Multi-unit residential building |
| MZ | Multi-zone |
| NECB | National Energy Code of Canada for Buildings |
| NG | Natural gas |
| NRCan | Natural Resources Canada |
| NREL | National Renewable Energy Laboratory |
| PRT | Packaged rooftop (typically gas-fired) |
| PSZ | Packaged single zone |
| PTAC | Packaged terminal air conditioner |
| RMZ | Recirculating multi-zone |
| SEER | Seasonal energy efficiency ratio |
| UBEM | Urban building energy model |
| VAV | Variable air volume |
| WWHP | Water-to-water heat pump |
Table 1
HVAC characterisation by commercial typology
| BUILDING | HVAC SYSTEMS |
|---|---|
| Mid-rise apartment | Split system units; exchanger (DX) cooling and NG furnace |
| Hospital | Water-cooled electric chiller, natural gas (NG) boiler, 2 varied air valve (VAV) and 2 constant air valve (CAV) systems |
| Large hotel | 2 air-cooled electric chillers, NG boiler, CAV, electric unit heater |
| Large office | 2 water-cooled chillers, VAV with reheat and plenum zones |
| Medium office | Packaged single zone air conditioner (PSZ) with plenum zones, NG furnace |
| Outpatient | DX cooling, NG boiler, 2 VAV systems with reheat |
| Primary school | P-VAV with hot water reheat; PSZ-AC, NG furnace |
| Quick service restaurant | PSZ-AC, NG furnace |
| Secondary school | Packaged DX, NG boiler, multi-zone (MZ)-CAV with reheat; PSZ-AC, NG furnace |
| Full-service restaurant | PSZ-AC, NG furnace |
| Small hotel | PTAC, electric unit heaters |
| Small office | PSZ-AC, NG furnace |
| Stand-alone retail | PSZ-AC, NG furnace; electric unit heater |
| Strip mall | PSZ-AC, NG furnace |
| Supermarket | PSZ-AC, NG furnace |
| Warehouse | PSZ-AC, NG furnace |
[i] Source: ASHRAE 2004.
Figure 1
Evolution of HVAC systems over time.
Source: Adapted from (Carrier 2012, US DOE 2015)
Figure 2
Evolution of typical heating efficiencies over different periods.
Source: Adapted from NRCan 1997b, NRCan 2011a.
Figure 3
Evolution of typical cooling equipment performance over different periods, converted from SEER values.
Source: Adapted from NRCan 1997b, NRCan 2011a.
Table 2
HVAC clusters based on classification and characterisation methods
| CLUSTER NUMBER | BUILDING TYPE(S) | PERIOD(S) | MODELLED SYSTEM TYPE | MINIMUM HEATING EFFICIENCY (%) | MINIMUM COOLING EFFICIENCY (COP) | MECHANICAL VENTILATION | EXPECTED LIFE |
|---|---|---|---|---|---|---|---|
| H1 | Smaller commercial (1–3 stories) | 1960–2004 | PRT-DX unit | 75 | 3.6 | Assumed none (operable windows) | 15–20 yrs |
| H2a | Mid-size commercial | pre-1960 | Non-condensing NG boiler and chiller with FCU | 4.5 | None | 20 yrs for the boiler | |
| H2b | Non-condensing NG boiler with hydronic heating | N/A | |||||
| H3a | Mid-size commercial | 1960–2004 | PRT-DX unit | 80 | 3.6 | Assumed none (operable windows) | Boiler 20 yrs max AHU 25+ yrs Chiller 15–20 yrs |
| H3b | Large commercial | 1960–2004 | Gas-fired RMZ AHU; water-cooled chiller | 4.5 | Multi-zone recirculating AHU w/VAV | boiler 20 yrs max AHU 25+ yrs Chiller 20–30 yrs | |
| H4a | Small MURBs | pre-1970 | Non-condensing NG boiler with hydronic heating | 75 | N/A | None | Boiler 20 yrs max |
| H4b | Small MURBs | pre-1970s | Non-condensing NG boiler with hydronic heating and window ACs | 3.16 | Boiler 20 yrs max. Window AC 10 yrs | ||
| H5 | Mid-Rise MURBs | post-1970 | Non-condensing NG boiler with hydronic heating and window ACs | 80 | Corridor pressurisation + kitchen/bathroom exhaust | ||
| H6 | Mid-rise and high-rise MURBs | 1980–2000 | Non-condensing NG boiler and chiller with FCU | 4.45 | Boiler 20 yrs max Chiller 20–30 yrs |
Table 3
HVAC retrofit suggestions for Toronto building archetypes
| CLUSTER NUMBER | MODELLED SYSTEM TYPE | DISTRIBUTION TYPE | EASIEST RETROFIT (R1) | HIGHEST ENERGY IMPACT RETROFIT (R2) | DISTRICT ENERGY ENABLED RETROFIT (R3) |
|---|---|---|---|---|---|
| H1 | PRT-DX unit | VAV AHU, perimeter induction units | Packaged air-to-air HP w/ electric auxiliary coil | Packaged air-to-air HP w/ VRF | — |
| H2a | Non-condensing NG boiler and chiller w/ FCU | FCU | Air-to-water HP w/ electric boiler auxiliary | High-temp WWHP (sourced from city supply) | |
| H2b | Non-condensing NG boiler with hydronic heating | Hot water radiators | High-temp WWHP w/ electric boiler auxiliary coil | ||
| H3a | PRT-DX unit | VAV AHU | Packaged air-to-air HP w/ electric auxiliary | Packaged air-to-air HP w/ VRF | — |
| H3b | Gas-fired RMZ AHU; water-cooled chiller | Central water loop HP | High-temp WWHP w/ hybrid VRF | High-temp WWHP (sourced from city supply) | |
| H4a | Non-condensing NG boiler with hydronic heating | Hot water radiators |
| High-temp WWHP w/ hybrid VRF | High-temp WWHP (sourced from city supply) |
| H4b | Non-condensing NG boiler with hydronic heating, window ACs | ||||
| H5 | |||||
| H6 | Non-condensing NG boiler, chiller w/ FCU | FCU |
|
|
|
[i] Source: Based on ASHRAE 2022; Purpose Building 2024; RDH Building Science 2024.
Figure 4
Annual CO2 emissions of baseline and retrofit systems in post-1960 small commercial buildings (H1) on North American climate zone 5 A grids.
Figure 5
Annual CO2 emissions of baseline and retrofit systems in pre-1960 mid-size commercial buildings with FCUs (H2a) on North American climate zone 5 A grids.
Figure 6
Annual CO2 emissions of baseline and retrofit systems in pre-1960 mid-size commercial buildings with hydronic heating (H2b) on North American climate zone 5 A grids.
Figure 7
Annual CO2 emissions of baseline and retrofit systems in post-1960 mid-size commercial buildings (H3a) on North American climate zone 5 A grids.
Figure 8
Annual CO2 emissions of baseline and retrofit systems in post-1960 large commercial buildings (H3b) on North American climate zone 5 A grids.
Figure 9
Annual CO2 emissions of baseline and retrofit systems in post-1970 mid-rise MURBs (H5) on North American climate zone 5 A grids.
Figure 10
Annual CO2 emissions of baseline and retrofit systems in post-1980 mid- and high-rise MURBs (H6) on North American climate zone 5 A grids.