# Decarbonizing Local Mobility and Greenhouse Agriculture through Residential Building Energy Upgrades: A Case Study for Québec

^{1}

^{2}

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## Abstract

**:**

^{−1}of electricity would be available for decarbonization, equivalent to a 19% and 12% increase of the province’s electricity supply for the retrofitted or rebuilt houses, respectively. This is enough energy to convert 83–100% of personal vehicles to BEVs or 35–56% to FCEVs. Decarbonization using the electricity that is made available by upgrading to low-energy solar houses could reduce the province’s greenhouse gas (GHG) emissions by approximately 32% (26.5 MtCO

_{2eq}). The time required for the initial embodied GHG emissions to surpass the emissions avoided by electrification ranges from 3.4 to 11.2 years. Building energy efficiency retrofits/rebuilds combined with photovoltaics is a promising approach for Québec to maximize the decarbonization potential of its existing energy resources while providing local energy and food security.

## 1. Introduction

## 2. Energy and Emissions Analysis

#### 2.1. House Characteristics

^{2}). Although the footprint of residential buildings in Canada has increased by approximately 20% in the last 30 years [1], future trends may be different as compact cities and environmentally friendly lifestyles are favored. For a balanced prediction given these uncertainties, the newly built houses were specified to have the same living area as its existing counterpart which also allows a fairer comparison of their energy performance. To build two houses on the same land lot (∼850 m

^{2}) while maximizing available outdoor space, the new homes will have two stories (Figure 2b). Similarly, the new houses will have an attached garage and a basement. The houses are equipped with heating and cooling and the upgraded houses also have energy recovery ventilation.

^{2}and 46.1 m

^{2}, producing 20.7 kW and 9.8 kW of peak electricity for the retrofitted and rebuilt houses, respectively. Additional details for the modeled houses can be found in a previous study by Bambara, Athienitis and Eicker [7].

#### 2.2. Greenhouse Characteristics

^{2}(10,000 sqft). More of the details for the greenhouse can be found in a previous study by Bambara and Athienitis [24].

#### 2.3. Energy Modeling and Simulation

**House energy performance**

**Greenhouse energy consumption**

^{−2}d

^{−1}to reflect their growing needs [28]. The heating energy is provided by burning natural gas inside the greenhouse. Other energy such as pumping, air circulation fans, etc. is taken as 34 kWh m

^{−2}and ventilation fan power is calculated using 4.7 W m

^{−3}h

^{−1}[30]. Table 2 provides the peak winter demand and monthly energy consumption that was obtained by summing hourly simulation output data.

#### 2.4. Energy Analysis

- The first part covers the energy analysis of a single-detached house to answer the following questions:
- 1.1.
- How much energy can be made available by upgrading an existing house to a low-energy solar house?
- 1.2.
- What is the maximum amount of mobility electrification that is achieved using upgrade energy?
- 1.3.
- How much energy is available for heating decarbonization and what is the maximum amount of greenhouse area that can be decarbonized/operated by using it?

- The second part consists of evaluating the impact of upgrading many houses to answer the following questions:
- 2.1.
- Scenario 1: How many houses should be upgraded to provide enough energy for decarbonizing/operating all of the greenhouses needed to achieve fresh vegetable production autonomy in Québec?
- 2.2.
- Scenario 1: How many houses should be upgraded to provide enough energy for decarbonizing/operating all of the greenhouses needed to achieve fresh vegetable production autonomy in Québec?

_{decarb}in kWh year

^{−1}) is found by summing the electricity that is freed up by implementing energy efficiency measures (E

_{eff}in kWh year

^{−1}) and the solar electricity generation (E

_{PV}in kWh year

^{−1}). The sum of these hourly values over one year provides the annual quantity of energy for the case where the house is retrofitted or rebuilt. Monthly totals are used to visualize and calculate some of the results.

_{EV}in kWh month

^{−1}) that is made available from the house energy upgrade. A value of one month was selected for convenience and because the hydropower grid with large reservoirs allows it to provide energy flexibly. Therefore, each month, an amount of energy equal to E

_{EV}is reserved for EVs. When the monthly value of upgrade energy exceeds E

_{EV}, the surplus serves to electrify heating. The annual quantity of electricity that is available for EVs is E

_{EV}multiplied by twelve.

_{EV}in km year

^{−1}) using the electricity that is provided by upgrading a single-detached house is given by:

- E
_{EV}is the monthly energy reserved for EVs (kWh month^{−1}) - EC
_{EV}is the BEV or FCEV energy consumption (kWh km^{−1}) - the factor 12 is the number of months per year (month year
^{−1}).

_{BEV}) was taken as the weighted value between cars (0.19 kWh km

^{−1}for 63% of personal vehicles) and light trucks (0.25 kWh km

^{−1}for 37% of personal vehicles) [31]. The energy consumption of a FCEV is estimated by comparing the efficiencies of BEV and FCEV for converting grid electricity into power at the wheels. The grid-to-wheel efficiency of a BEV is estimated to be 83% by multiplying the following efficiencies: 97% for the AC/DC inverter, 95% for the batteries, 97% for the DC/AC inverter, and 93% for the electric motor [32]. The grid-to-wheel efficiency of an FCEV is taken as 35% by multiplying the following efficiencies and assuming hydrogen is produced directly at the refuel station: 97% for the AC/DC inverter, 73% for water electrolysis, 92% for hydrogen compression, 60% for the fuel cell, 97% for the DC/AC inverter, and 93% for the electric motor [32,33]. The ratio of these efficiencies (R

_{BEV:FCEV}) equals 2.37 (83%/35%), meaning that a FCEV requires that many times more energy than the BEV for a similar range. The energy consumption (EC

_{FCEV}) of a personal FCEV is found by multiplying the energy consumption of a BEV (EC

_{BEV}) by this ratio of efficiencies (R

_{BEV:FCEV}). If the energy that is made available by upgrading a given number of houses exceeds the need for electrifying all the personal vehicles, then the surplus energy can be used to decarbonize other vehicles such as fuel cell electric trucks (FCET) for regional or long-haul transport. The energy consumption of a FCET (EC

_{FCET}) is estimated the same way as for the FCEV using the energy consumption for battery electric trucks (BET) provided by Ref. [34].

_{EV}) is calculated by:

_{EV_yr}is the personal EV annual travel distance (km year

^{−1}).

_{EV}in kWh month

^{−1}) from the monthly amount of upgrade energy (E

_{decarb_mo}in kWh month

^{−1}). The amount of power available during periods of peak demand is found by subtracting the EV power demand from the maximum hourly value of power that is freed up by implementing energy efficiency measures. The contribution of solar energy is ignored as it is not guaranteed to be available during peak periods. The power demand from EV is assumed to be constant with time and calculated by dividing the monthly amount that is reserved for EV (E

_{EV}in kWh month

^{−1}) by the number of hours in one month.

_{GH}in kWh year

^{−1}) is given by:

- E
_{decarb}is the electricity available from upgrading one house (kWh year^{−1}) - the factor 12 is the number of months per year (month year
^{−1}).

_{GH_per_house}in m

^{2}) which minimizes the annual difference between the house upgrade energy and the actual energy consumed by a given greenhouse area. The greenhouse area based on power availability can be found by dividing the power that is dedicated to greenhouses (P

_{max}in kW, obtained by subtracting the EV power demand (P

_{EV}in kW) from the maximum power freed up by implementing efficiency measures (P

_{eff}in kW)) by the greenhouse’s peak power demand per unit area (P

_{GH}in kW m

^{−2}). The calculated greenhouse areas (A

_{GH_per_house}calculated for existing and new greenhouse) based on energy and power are compared and the lowest value obtained is selected as the final design. The annual thermal energy consumed by the existing greenhouses (E

_{GH_exist_per_house}in kWh year

^{−1}) that are heated using the electricity that is made available from upgrading a house is determined from:

- A
_{GH_exist_per_house}is the greenhouse area that can be decarbonized from one house upgrade (m^{2}) - E
_{GH_heat}is the electricity consumed for heating per unit area of a greenhouse (kWh m^{−2}year^{−1}).

_{GH_new_per_house}in kWh year

^{−1}) that are operated using the upgrade energy may be written as:

- A
_{GH_new_per_house}is the greenhouse area that can be operated from one house upgrade (m^{2}) - E
_{GH}is the electricity consumed per unit area of a greenhouse (kWh m^{−2}year^{−1}).

^{2}is used to grow 41,000 t year

^{−1}of vegetables in Québec [29]. The government has plans and established financial incentives to achieve fresh vegetable production autonomy by doubling the greenhouse production area by 2025 [8,35]. Therefore, approximately 1,280,000 m

^{2}of additional greenhouse area would be needed to produce a total of 82,000 tonnes of vegetables per year.

_{house_GH_exist}) needed to provide enough power for electrifying the heating in all existing greenhouses is estimated using:

_{GH_tot_exist}is the total existing greenhouse area (m

^{2}).

_{house_GH_new}) needed to provide enough electricity for operating all the new greenhouses is determined from:

_{GH_tot_new}is the total new greenhouse area (m

^{2}).

_{house_GH_tot}) is defined as:

_{upgraded_GH}in %) is derived from:

- N
_{house_tot}is the total number of single-detached homes in Québec - the factor 100 serves to express the result in percentage.

_{decarb_tot}in TWh year

^{−1}) is calculated as:

- E
_{decarb}is the electricity that is available for decarbonization (kWh year^{−1}) - the factor 10
^{9}serves to convert kWh to TWh (month year^{−1}).

_{decarb}in %) is determined by dividing total electricity that is available for decarbonization (E

_{decarb_tot}) by the total electricity consumption in Québec (E

_{QC}in TWh year

^{−1}) and multiplying this by 100 to express the result in percentage.

_{GH_tot}in TWh year

^{−1}) is computed as:

^{9}serves to convert kWh to TWh (month year

^{−1}).

_{GH_heat_tot}in TWh year

^{−1}) that is used solely for heating the existing and new greenhouses will be needed to determine the avoided GHG emissions and is described by:

^{9}serves to convert kWh to TWh (month year

^{−1}).

_{EV_tot}in TWh year

^{−1}) is calculated by:

^{−1}) and 10

^{9}serves to convert kWh to TWh (month year

^{−1}).

_{leftover}in TWh year

^{−1}) and available for other decarbonization purposes such as electrifying heating in buildings that employ natural gas is expressed as:

_{EV_tot}) is given by:

_{EV_tot}in %) is estimated using:

- N
_{PV_tot}is the total number of personal vehicles - the factor 100 serves to express the result in percentage.

_{house_added}) equal to:

_{house_EH_tot}is the number of houses that use electric resistance heating.

_{GH_tot}is ignored), (15), and (16), but using N

_{house_added}instead of N

_{house_GH_tot}. The total values for scenario 2 are the sum of the contributions from N

_{house_GH_tot}and N

_{house_added}.

#### 2.5. GHG Emissions Analysis

**GHG emissions avoided by decarbonization**

_{EV_per_house}in tCO

_{2eq}) that can be achieved using a portion of the upgrade energy is determined from:

- FE
_{PV}is the average fuel efficiency of personal vehicles (L km^{−1}) - EF
_{PV}is the emissions factor of gasoline-powered personal vehicles (kgCO_{2eq}L^{−1}) - the factor 1000 serves to convert kg to tonne (t).

_{FCET}in MtCO

_{2eq}year

^{−1}) is estimated using:

- E
_{FCET}is the surplus electricity available for FCETs (kWh year^{−1}) - EC
_{FCET}is the FCET energy consumption (kWh km^{−1}) - FE
_{T}is the average fuel efficiency of a diesel-powered truck (L km^{−1}) - EF
_{T}is the emissions factor of diesel-powered truck (kgCO_{2eq}L^{−1}) - the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{EV}in MtCO

_{2eq}year

^{−1}) in scenario 1 (N

_{house_GH_tot}) or scenario 2 (N

_{house_EH_tot}) is given by:

^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{GH}in MtCO

_{2eq}year

^{−1}) from electrifying the heating in existing greenhouses and from the emissions that are avoided by employing electric heating in the new greenhouses (assuming they would otherwise be heated using natural gas burned inside the greenhouse) is calculated by:

- EF
_{NG}is the emissions factor of natural gas (kgCO_{2eq}m^{−3}) - EV is the energy value of natural gas (MJ m
^{−3}) - the factor 10
^{9}serves to convert TWh to kWh - the factor 3.6 serves to convert MJ to kWh
- the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{leftover}in MtCO

_{2eq}year

^{−1}) to convert building heating from natural gas boilers to electric heat pumps is approximated by:

- η is the natural gas boiler efficiency (dimensionless)
- COP is the average coefficient of performance of an electric heat pump (MJ m
^{−3}) - the factor 10
^{9}serves to convert TWh to kWh - the factor 3.6 serves to convert MJ to kWh
- the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{tot}in MtCO

_{2eq}year

^{−1}) is equal to:

_{GHG}in %) is expressed as:

- GHG
_{QC}is Québec’s total annual GHG emissions (MtCO_{2eq}year^{−1}) - the factor 100 serves to express the result in percentage.

**Embodied GHG emissions**

_{houses}in MtCO

_{2eq}) in scenario 1 (N

_{house_GH_tot}) or scenario 2 (N

_{house_EH_tot}) is calculated by:

- EE
_{house}is the embodied emissions per unit area for a retrofitted or rebuilt house (kgCO_{2eq}m^{−2}) - A is the living area of the house (m
^{2}) - the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{PV}in MtCO

_{2eq}) in scenario 1 (N

_{house_GH_tot}) or scenario 2 (N

_{house_EH_tot}) is estimated using:

- EE
_{PV_m2}is the embodied emissions per unit area of the PV system (kgCO_{2eq}m^{−2}) - A
_{PV}is PV area (m^{2}) - the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{FCETs}in MtCO

_{2eq}) is determined from:

- D
_{ET_yr}is the FCET annual travel distance (km year^{−1}) - EE
_{FCET}is the embodied emissions per truck (kgCO_{2eq}) - the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{EVs}in MtCO

_{2eq}) in scenario 1 (N

_{house_GH_tot}) or scenario 2 (N

_{house_EH_tot}) is computed as:

- the factor 1000 serves to convert kg to tonne (t)
- the factor 10
^{6}serves to convert tonnes (t) to megatonnes (Mt).

_{tot}in MtCO

_{2eq}) are approximated by:

**Emissions payback time**

_{GHG}in yr) is equal to:

Parameter | Value | Reference |
---|---|---|

Living area of existing, retrofitted and rebuilt houses (A) | 140 m^{2} | [7] |

PV area (A_{PV}) (value for rebuilt house in parenthesis) | 97.7 (46.1) m^{2} | [7] |

BEV energy consumption for (EC_{BEV}) | 0.22 kWh km^{−1} | [31] |

FCEV energy consumption for (EC_{FCEV}) | 0.52 kWh km^{−1} | Calculated |

BET energy consumption for (EC_{BET}) | 1.15 kWh km^{−1} | [34] |

FCET energy consumption for (EC_{FCET}) | 2.73 kWh km^{−1} | Calculated |

Electric vehicle annual travel distance (D_{EV_yr}) | 14,800 km year^{−1} | [37] |

Electric truck annual travel distance (D_{ET_yr}) | 120,000 km year^{−1} | [34] |

Total number of personal vehicles (N_{PV_tot}) | 5,400,000 | [38] |

Total number of single-detached houses (N_{house_tot}) | 1,735,000 | [39] |

Single-detached houses with electric resistance heating (N_{house_EH_tot}) | 734,000 | [39] |

Emissions factor for gasoline-powered personal vehicles (EF_{PV}) | 2.3 kgCO_{2eq} L^{−1} | [31] |

Average fuel efficiency for personal vehicles (FE_{PV}) | 0.1 L km^{−1} | [37] |

Emissions factor for diesel-powered trucks (EF_{T}) | 2.7 kgCO_{2eq} L^{−1} | [40] |

Average fuel efficiency for trucks (FE_{PV}) | 0.4 L km^{−1} | [41] |

Emissions factor for natural gas (EF_{NG}) | 1.9 kgCO_{2eq} m^{−3} | [42] |

Energy value of natural gas (EV) | 37 MJ m^{−3} | [43] |

Boiler efficiency (η) | 0.8 | [44] |

Average COP of electric heat pump (COP) | 3 | [3] |

Total electricity consumption in Québec (E_{QC}) | 174.6 TWh year^{−1} | [1] |

Total annual GHG emissions in Québec (GHG_{QC}) | 82 MtCO_{2eq} | [1] |

Embodied emissions for house rebuilds (EE_{house_rebuild_m2}) | 600 kgCO_{2eq} m^{−2} | [45] |

Embodied emissions for house retrofits (EE_{house_retrofit_m2}) | 120 kgCO_{2eq} m^{−2} | [21] |

PV system embodied emissions (EE_{PV_m2}) | 300 kgCO_{2eq} m^{−2} | [46] |

Embodied emissions per BEV (EE_{BEV}) | 9900 kgCO_{2eq} | [47] |

Embodied emissions per FCEV (EE_{FCEV}) | 7400 kgCO_{2eq} | [47] |

Embodied emissions per FCET (EE_{FCET}) | 148,000 kgCO_{2eq} | Estimated based on weight |

## 3. Results and Discussion

#### 3.1. Energy Available by Upgrading a House

^{−1}of electricity being freed up and available for decarbonization elsewhere. In addition, the retrofitted and rebuilt houses generate approximately 14,800 kWh year

^{−1}and 31,300 kWh year

^{−1}of solar electricity on-site, respectively. This large difference is caused by the retrofitted house having a PV area more than double the size of the rebuilt house. The simulated solar energy production for the rebuilt house (14,800 kWh year

^{−1}) is in good agreement with a simple calculation that yields 15,500 kWh year

^{−1}based on the annual global radiation on a south-facing surface at a tilt angle equal to the latitude for Montreal (4.35 kWh m

^{−2}year

^{−1}) provided by Ref. [48], a PV module efficiency of 21.16%, and a PV area of 46.1 m

^{2}.

^{−1}per retrofitted house and 29,500 kWh year

^{−1}per rebuilt house. In other words, the retrofitted house could provide energy for decarbonization that is equal to twice the electricity consumption of the existing house and 1.3 times more for the rebuilt house. Solar energy provides 50% and nearly 70% of the total upgrade energy for the retrofitted and rebuilt houses, respectively, with the remainder provided by the efficiency measures. Meanwhile, the amount of energy that is freed up due to efficiency is highest during periods of peak demand in winter and is found to be 7.1 and 7.3 kW per retrofitted and rebuilt house, respectively. When the electricity that is made available by upgrading to a low-energy solar house is used to decarbonize elsewhere, the amount of energy and peak power that is required for the electrified load must not exceed these values.

^{−2}month

^{−1}(in summer) and this is what limits the electricity that can be reserved year-round for EVs. For solar electricity generation (red line in Figure 4a), the minimum value is 8 kWh m

^{−2}month

^{−1}in November. However once combined (green line in Figure 4a), the minimum value becomes 19 kWh m

^{−2}month

^{−1}(in November), which is 90% more than the sum of the minimum values for efficiency and solar individually (total of 10 kWh m

^{−2}month

^{−1}). Therefore, the efficiency and solar combo can achieve the desired goal of attributing a greater share of the total upgrade energy for EV, and the remainder is concentrated in winter and is ideal for heating decarbonization (Figure 5). It would be possible to use an alternative source of energy such as biomass to assist solar electricity production in winter (neglects efficiency) or to complement efficiency in summer (neglects solar) to achieve a constant annual energy profile. However, this study focuses on how to employ energy from building upgrades as the sole means for providing energy needed for decarbonization.

#### 3.2. Heating Decarbonization

^{2}of the existing greenhouse and operate 7 m

^{2}of the new greenhouse. Both of these areas were selected based on the availability of peak power. Rebuilding a house can provide enough electricity to heat 14.1 m

^{2}of existing greenhouse (selected based on energy availability) and to operate 10.1 m

^{2}of new greenhouse (selected based on peak power availability).

^{−1}of electricity and would add nearly 1000 MW of peak demand to the existing grid. This represents a 2.6% increase compared to today’s peak demand of approximately 39,000 MW [5], or half of the new peak demand that is predicted to be required in the province by 2029 [15]. As shown in Table 6, all the energy needed to have an entirely local and decarbonized supply of fresh vegetables can be achieved by retrofitting 16% or rebuilding 12% of single-detached homes in Québec, respectively.

^{−1}of surplus electricity for decarbonizing heating in other buildings for the retrofitted and rebuilt houses, respectively. The total energy that is made available by retrofitting and rebuilding these houses equals 33.4 and 21.8 TWh year

^{−1}or 19% and 12% of the total electricity consumption of the province, respectively.

#### 3.3. Mobility Decarbonization

^{−1}for the retrofitted house and 1652 kWh month

^{−1}for the rebuilt house. The rebuilt house provides 38% less energy for EVs than the retrofit house because less solar electricity is generated by its smaller roof area. Approximately 70% of the house upgrade energy can serve to electrify mobility. This energy is sufficient to power 9.8 and 6.1 personal BEVs for the retrofitted and rebuilt houses, respectively. For FCEVs, this energy is sufficient to power 4.1 and 2.6 personal vehicles for the retrofitted and rebuilt houses, respectively. The lower values for FCEVs are due to their lower well-to-wheel efficiency compared to BEV (35% versus 82%).

^{−1}of electricity would be available to decarbonize mobility for the retrofitted and rebuilt house, respectively. This would provide enough energy to convert 52% and 24% of personal vehicles to BEVs and 22% and 10% to FCEVs for the retrofitted and rebuilt house, respectively.

^{−1}of electricity would be available to decarbonize mobility for the retrofitted and rebuilt house, respectively. This would provide enough energy to convert 133% and 83% of personal vehicles to BEVs and 56% and 35% to FCEVs for the retrofitted and rebuilt house, respectively. For the case where BEVs are powered using energy that is made available by retrofitting houses, there is more than enough energy to cover all the energy required for personal vehicles. This surplus energy can be used for other mobility electrification purposes such as producing hydrogen for long-haul fuel cell electric trucks.

#### 3.4. GHG Emissions Analysis

_{2eq}year

^{−1}) whereas for scenario 2, emission reductions of 12–32% (10.2–26.5 MtCO

_{2eq}year

^{−1}) could be achieved.

#### 3.5. Benefits of Densification

#### 3.6. Comparison to Alternative Low-Emission Energy Supply Solutions

## 4. Conclusions

^{−1}) and 1.3 times more (about 29,500 kWh year

^{−1}) for the rebuilt house. This “new” electricity is characterized by an annual profile that is greater in winter, allowing it to serve for the electrification of both mobility and heating. It was found that retrofitting 12% or rebuilding 16% of single-detached houses in Québec could provide enough energy to decarbonize the heating energy used for all existing greenhouses and operate all the new greenhouses that are required to achieve local fresh vegetable production autonomy.

^{−1}which is equivalent to a 19% and 12% increase of the province’s electricity supply for the retrofitted and rebuilt houses, respectively. In addition to decarbonizing the energy used by all greenhouses, 7.9 and 5.1 TWh year

^{−1}would be available to electrify the heating energy used in other buildings, for instance by switching from a natural gas boiler to electric heat pumps, which are becoming essential because they can provide both heating and cooling which is increasingly needed with rising summer temperatures. Approximately 70% of the total house upgrade electricity or 14.6 and 23.4 TWh year

^{−1}can be dedicated to electrifying mobility, which is enough to convert 83% and 100% of the personal vehicles to BEVs and 35% and 56% to FCEVs for the rebuilt and retrofitted houses, respectively. The available electricity that is more than the requirements for personal vehicles can serve to decarbonize other vehicles such as public transportation or delivery vehicles.

_{2eq}year

^{−1}from greenhouse heating electrification, by 3.5 and 5.4 MtCO

_{2eq}year

^{−1}from electrifying heating in other buildings, by 19 and 26.5 MtCO

_{2eq}year

^{−1}from switching to BEVs, or by 10.2 and 16.1 MtCO

_{2eq}year

^{−1}from switching to FCEVs for the rebuilt and retrofitted houses, respectively. Using house upgrade energy for decarbonization could reduce the province’s emissions by up to 32% (26.5 MtCO

_{2eq}year

^{−1}). Meanwhile, the building upgrades and production of EVs generate emissions of up to 116.1 MtCO

_{2eq}year

^{−1}. The time required for these embodied emissions to surpass the emissions avoided by electrification ranged from 3.4 to 11.2 years (retrofits have a significantly shorter emissions payback and should be prioritized when appropriate). Therefore, emissions will initially increase before the desired reductions occur and finding ways to minimize this is a major challenge of the sustainable transition.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Nomenclature

Symbol | |

A | Living area of the existing, retrofitted and rebuilt house (m^{2}) |

A_{GH_exist_per_house} | Greenhouse area that can be decarbonized from one house upgrade (m^{2}) |

A_{GH_tot_exist} | Total existing greenhouse area (m^{2}) |

A_{GH_tot_new} | Total new greenhouse area (m^{2}) |

A_{PV} | PV area (m^{2}) |

COP | Average coefficient of performance of an electric heat pump (MJ m^{−3}) |

D_{ET_yr} | FCET annual travel distance (km year^{−1}) |

D_{EV} | Annual distance EVs (BEVs or FCEVs) can travel (km year^{−1}) |

D_{EV_yr} | Annual travel distance of a vehicle (km year^{−1}) |

EC | Energy consumption (kWh km^{−1}) |

EC_{FCET} | FCET energy consumption (kWh km^{−1}) |

E_{decarb} | Annual electricity made available by low-energy solar house upgrade (kWh year^{−1}) |

E_{decarb_mo} | Monthly amount of upgrade energy (kWh month^{−1}) |

E_{decarb_tot} | Total electricity that is available for decarbonization (TWh year^{−1}) |

EE_{EVs} | Embodied emissions related to the production of EVs (MtCO_{2eq}) |

EE_{FCET} | Embodied emissions per truck (kgCO_{2eq}) |

EE_{FCETs} | Embodied emissions related to the production of FCETs (MtCO_{2eq}) |

E_{eff} | Annual electricity made available from efficiency measures (kWh year^{−1}) |

EE_{house} | Embodied emissions per unit area for a retrofitted or rebuilt house (kgCO_{2eq} m^{−2}) |

EE_{houses} | Embodied emissions produced by retrofitting or rebuilding the houses (MtCO_{2eq}) |

EE_{PV} | Embodied emissions produced by the PV system (MtCO_{2eq}) |

EE_{PV_m2} | Embodied emissions per unit area of the PV system (kgCO_{2eq} m^{−2}) |

EE_{tot} | Total embodied emissions (in MtCO_{2eq}) |

E_{EV} | Monthly energy reserved for EVs (kWh month^{−1}) |

E_{EV_tot} | Total electricity for EV (TWh year^{−1}) |

E_{FCET} | Surplus electricity available for FCETs (kWh year^{−1}) |

EF_{NG} | Emissions factor of natural gas (kgCO_{2eq} m^{−3}) |

EF_{T} | Emissions factor of diesel-powered truck (kgCO_{2eq} L^{−1}) |

E_{GH} | Electricity consumed per unit area of a greenhouse (kWh m^{−2} year^{−1}) |

E_{GH} | Annual electricity that is available for greenhouses (kWh year^{−1}) |

E_{GH_exist_per_house} | Annual thermal energy consumed by the existing greenhouses (in kWh year^{−1}) |

E_{GH_heat} | Electricity consumed for heating per unit area of a greenhouse (kWh m^{−2} year^{−1}) |

E_{GH_heat_tot} | Electricity that is used solely for heating the greenhouses (TWh year^{−1}) |

E_{GH_new_per_house} | Annual energy consumed by the new greenhouses (kWh year^{−1}) |

E_{GH_tot} | Total electricity consumed for decarbonizing the greenhouses (TWh year^{−1}) |

E_{leftover} | Leftover electricity (TWh year^{−1}) |

E_{PV} | Annual solar electricity generation from photovoltaics (kWh year^{−1}) |

E_{QC} | Total electricity consumption in Québec (TWh year^{−1}) |

EV | Energy value of natural gas (MJ m^{−3}) |

F_{decarb} | Fraction of total electricity consumption (%) |

FE_{PV} | Average fuel efficiency of personal vehicles (L km^{−1}) |

FE_{T} | Average fuel efficiency of a diesel-powered truck (L km^{−1}) |

F_{EV_tot} | Fraction of total personal vehicles that could be converted to EVs (%) |

F_{PV} | Emissions factor of gasoline-powered personal vehicles (kgCO_{2eq} L^{−1}) |

F_{upgraded_GH} | Fraction of total single-detached houses that would need to be upgraded (%) |

GHG_{EV} | Reduction in emissions achieved by electrifying mobility (MtCO_{2eq} year^{−1}) |

GHG_{EV_per_house} | Reduction in emissions from mobility electrification (tCO_{2eq}) |

GHG_{FCET} | Reduction in emissions (in MtCO_{2eq} year^{−1}) |

GHG_{GH} | Reduction in emissions from decarbonizing greenhouses (MtCO_{2eq} year^{−1}) |

GHG_{leftover} | Reduction in emissions achieved using the leftover electricity (MtCO_{2eq} year^{−1}) |

GHG_{QC} | Québec’s total annual GHG emissions (MtCO_{2eq} year^{−1}) |

GHG_{tot} | Total reduction in emissions (MtCO_{2eq} year^{−1}) |

N_{EV} | Number of EVs (BEVs or FCEVs) that can be powered using upgrade energy |

N_{EV_tot} | Total number of EVs (BEVs or FCEVs) |

N_{house_added} | Additional number of houses |

N_{house_EH_tot} | Number of houses that use electric resistance heating |

N_{house_GH_exist} | Number of houses needed to provide energy for heating existing greenhouses |

N_{house_GH_new} | Number of houses needed to provide energy for operating new greenhouses |

N_{house_GH_tot} | Total number of houses that would need to be upgraded |

N_{house_tot} | Total number of single-detached homes in Québec |

N_{PV_tot} | Total number of personal vehicles |

P_{eff} | Maximum power freed up by implementing efficiency measures (kW) |

P_{EV} | EV power demand (kW) |

P_{GH} | Greenhouse peak power demand per unit area (kW m^{−2}) |

P_{max} | Power availability from a house (kW) |

PT_{GHG} | Emissions payback time (yr) |

R_{BEV:FCEV} | Ratio of grid-to-wheel efficiency efficiencies |

R_{GHG} | Reduction in Québec’s emissions (%) |

η | Natural gas boiler efficiency (dimensionless) |

## References

- Whitmore, J.; Pineau, P.-O. État de L’énergie au Québec; Minister of Energy and Natural Resources: Montréal, QC, Canada, 2021.
- Albatayneh, A.; Assaf, M.N.; Alterman, D.; Jaradat, M. Comparison of the Overall Energy Efficiency for Internal Combustion Engine Vehicles and Electric Vehicles. Environ. Clim. Technol.
**2020**, 24, 669–680. [Google Scholar] [CrossRef] - Carroll, P.; Chesser, M.; Lyons, P. Air Source Heat Pumps field studies: A systematic literature review. Renew. Sustain. Energy Rev.
**2020**, 134, 110275. [Google Scholar] [CrossRef] - Inner City Fund (ICF). Implications of Policy-Driven Electrification in Canada; A Canadian Gas Association Study Prepared by ICF; ICF: Ottawa, ON, Canada, 2019. [Google Scholar]
- Hydro-Québec. État D’avancement 2018 du plan D’approvisionnement 2017–2026; Hydro-Québec: Montréal, QC, Canada, 2018. [Google Scholar]
- Office of Energy Efficiency—Residential Sector. Québec. Table 21: Heating System Stock by Building Type and Heating System Type. 2018. Available online: https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/showTable.cfm?type=CP§or=res&juris=qc&rn=21&page=0 (accessed on 9 June 2021).
- Bambara, J.; Athienitis, A.K.; Eicker, U. Residential Densification for Positive Energy Districts. Front. Sustain. Cities
**2021**, 3, 3. [Google Scholar] [CrossRef] - Programme de Soutien au Développement des Entreprises Serricoles 2020–2024. Available online: https://www.mapaq.gouv.qc.ca/fr/Productions/md/programmesliste/productionhorticole/Pages/programme-soutien-developpement-entreprises-serricoles.aspx (accessed on 11 June 2021).
- Vadiee, A.; Martin, V. Energy analysis and thermoeconomic assessment of the closed greenhouse—The largest commercial solar building. Appl. Energy
**2013**, 102, 1256–1266. [Google Scholar] [CrossRef] - Anifantis, A.S.; Colantoni, A.; Pascuzzi, S.; Santoro, F. Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study. Sustainability
**2018**, 10, 378. [Google Scholar] [CrossRef] [Green Version] - Bambara, J.; Athienitis, A.K. Energy and economic analysis for the design of greenhouses with semi-transparent photovoltaic cladding. Renew. Energy
**2019**, 131, 1274–1287. [Google Scholar] [CrossRef] - Greenhouse Heating with Biomass. Available online: https://www.saatotuli.ca (accessed on 11 June 2021).
- Sturm, B.; Maier, M.; Royapoor, M.; Joyce, S. Dependency of production planning on availability of thermal energy in commercial greenhouses—A case study in Germany. Appl. Therm. Eng.
**2014**, 71, 239–247. [Google Scholar] [CrossRef] - Moreno, J.R.; Pinna-Hernández, G.; Fernández, M.F.; Molina, J.S.; Díaz, F.R.; Hernández, J.L.; Fernández, F.A. Optimal processing of greenhouse crop residues to use as energy and CO
_{2}sources. Ind. Crop. Prod.**2019**, 137, 662–671. [Google Scholar] [CrossRef] - Hydro-Québec. Plan D’approvisionnement 2020–2029; Hydro-Québec: Montréal, QC, Canada, 2019. [Google Scholar]
- Hydro-Québec. Dynamic Pricing. Available online: https://www.hydroquebec.com/residential/customer-space/rates/dynamic-pricing.html (accessed on 9 June 2021).
- Belussi, L.; Barozzi, B.; Bellazzi, A.; Danza, L.; Devitofrancesco, A.; Fanciulli, C.; Ghellere, M.; Guazzi, G.; Meroni, I.; Salamone, F.; et al. A review of performance of zero energy buildings and energy efficiency solutions. J. Build. Eng.
**2019**, 25, 100772. [Google Scholar] [CrossRef] - Ifeu; Fraunhofer IEE; Consentec. Building Sector Efficiency: A Crucial Component of the Energy Transition; A Study Commissioned by Agora Energiewende; European Climate Foundation: Berlin, Germany, 2018. [Google Scholar]
- Athienitis, A.K.; O’Brien, W. Modeling, Design, and Optimization of Net-Zero Energy Buildings; John Wiley & Sons: Toronto, ON, Canada, 2015. [Google Scholar]
- Asaee, S.R.; Nikoofard, S.; Ugursal, V.I.; Beausoleil-Morrison, I. Techno-economic assessment of photovoltaic (PV) and building integrated photovoltaic/thermal (BIPV/T) system retrofits in the Canadian housing stock. Energy Build.
**2017**, 152, 667–679. [Google Scholar] [CrossRef] [Green Version] - Feng, H.; Liyanage, D.R.; Karunathilake, H.; Sadiq, R.; Hewage, K. BIM-based life cycle environmental performance as-sessment of single-family houses: Renovation and reconstruction strategies for aging building stock in British Columbia. Clean. Prod.
**2020**, 250, 119543. [Google Scholar] [CrossRef] - Oberegger, U.F.; Pernetti, R.; Lollini, R. Bottom-up building stock retrofit based on levelized cost of saved energy. Energy Build.
**2020**, 210, 109757. [Google Scholar] [CrossRef] - ur Rehman, H.; Hirvonen, J.; Jokisalo, J.; Kosonen, R.; Sirén, K. EU Emission Targets of 2050: Costs and CO
_{2}Emissions Comparison of Three Different Solar and Heat Pump-Based Community-Level District Heating Systems in Nordic Conditions. Energies**2020**, 13, 4167. [Google Scholar] [CrossRef] - Bambara, J.; Athienitis, A.K. Energy and Economic Analysis for Greenhouse Envelope Design. Trans. ASABE
**2018**, 61, 1795–1810. [Google Scholar] [CrossRef] - Klein, S.A.; Duffie, J.A.; Mitchell, J.C.; Kummer, J.P.; Thornton, J.W.; Bradley, D.E.; Kummert, M. Mathematical Reference. In TRNSYS 17; Solar Energy Laboratory, University of Wisconsin: Madison, WI, USA, 2014; Volume 4. [Google Scholar]
- Hydro-Québec. Consumption Based on the Home’s Specific Features. Available online: https://www.hydroquebec.com/residential/customer-space/electricity-use/tools/electricity-use.html (accessed on 18 March 2020).
- Proulx-Gobeil, G.; Dion, L.M. Evaluation du Chauffage à L’électricité pour les Serres. Journée provinciale en sericulture—Maraichère et Ornementale; Québec Reference Center for Agriculture and Agri-Food (CRAAQ): Québec City, QC, Canada, 2015.
- Tomatoes under Lights. Available online: http://magazine.greenhousecanada.com/publication/?i=62359&p=26 (accessed on 11 June 2021).
- Agri-Food Canada. Statistical Overview of the Canadian Greenhouse Vegetable Industry—2019; Crops and Horticulture Division, Agriculture and Agri-Food Canada: Ottawa, ON, Canada, 2020.
- Posterity Group. Greenhouse Energy Profile Study; ALL ABOVE 32 IS MINUS 1; Posterity Group: Ottawa, ON, Canada, 2019. [Google Scholar]
- Natural Resources Canada. Fuel Consumption Guide. Available online: https://www.nrcan.gc.ca/energy-efficiency/transportation-alternative-fuels/fuel-consumption-guide/21002 (accessed on 29 June 2021).
- Handwerker, M.; Wellnitz, J.; Marzbani, H. Comparison of Hydrogen Powertrains with the Battery Powered Electric Vehicle and Investigation of Small-Scale Local Hydrogen Production Using Renewable Energy. Hydrogen
**2021**, 2, 76–100. [Google Scholar] [CrossRef] - International Energy Agency Technology Roadmap. Hydrogen and Fuel Cells. Available online: https://www.iea.org/reports/technology-roadmap-hydrogen-and-fuel-cells (accessed on 29 June 2021).
- Comparing Hydrogen and Battery Electric Trucks. Available online: https://www.transportenvironment.org/publications/comparing-hydrogen-and-battery-electric-trucks (accessed on 29 June 2021).
- Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec (MAPAQ). Portrait-Diagnostic Sectoriel des Légumes de Serre au Québec; MAPAQ: Québec City, QC, Canada, 2018.
- National Renewable Energy Laboratory. Life Cycle Greenhouse Gas Emissions from Solar Photovoltaics; U.S. Department of Energy: Golden, CO, USA, 2012.
- Transport Canada. Road Transportation—Table RO4: Light Vehicle Statistics by Province/Territory (2009). Available online: https://tc.canada.ca/en/corporate-services/policies/road-transportation-0 (accessed on 29 June 2021).
- Statistics Canada. Vehicle Registrations in Québec, by Type of Vehicle (2019) (Vehicles Weighing Less than 4500 Kilograms). Available online: https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=2310006701&pickMembers%5B0%5D=1.6&cubeTimeFrame.startYear=2018&cubeTimeFrame.endYear=2019&referencePeriods=20180101%2C20190101 (accessed on 29 June 2021).
- Office of Energy Efficiency. Residential Sector. Québec. Table 22: Single Detached Heating System Stock by Heating System Type. Office of Energy Efficiency. Available online: https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/showTable.cfm?type=CP§or=res&juris=qc&rn=22&page=0 (accessed on 17 June 2021).
- Environmental Protection Agency. Greenhouse Gases Equivalencies Calculator—Calculations and References. Available online: https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references (accessed on 17 June 2021).
- Natural Resources Canada. Fuel Efficiency Benchmarking in Canada’s Trucking Industry. 1999. Available online: https://www.nrcan.gc.ca/energy/efficiency/transportation/commercial-vehicles/reports/7607 (accessed on 29 June 2021).
- Environment and Climate Change Canada. National Inventory Report 1990–2014: Greenhouse Gas Sources and Sinks in Canada; Environment and Climate Change Canada: Gatineau, QC, Canada, 2016.
- Canada Energy Regulator. Energy Conversion Tables. Available online: https://apps.cer-rec.gc.ca/Conversion/conversion-tables.aspx?GoCTemplateCulture=en-CA (accessed on 24 June 2021).
- U.S. Boiler Company. What Is a High Efficiency Gas Boiler? Available online: https://www.usboiler.net/what-is-a-high-efficiency-gas-boiler.html (accessed on 24 June 2021).
- Tavares, V.; Lacerda, N.; Freire, F. Embodied energy and greenhouse gas emissions analysis of a prefabricated modular house: The “Moby” case study. J. Clean. Prod.
**2019**, 212, 1044–1053. [Google Scholar] [CrossRef] - Kristjansdottir, T.F.; Good, C.S.; Inman, M.R.; Schlanbusch, R.D.; Andresen, I. Embodied greenhouse gas emissions from PV systems in Norwegian residential Zero Emission Pilot Buildings. Sol. Energy
**2016**, 133, 155–171. [Google Scholar] [CrossRef] - Ambrose, H.; Kendall, A.; Lozano, M.; Wachche, S.; Fulton, L. Trends in life cycle greenhouse gas emissions of future light duty electric vehicles. Transp. Res. Part D Transp. Environ.
**2020**, 81, 102287. [Google Scholar] [CrossRef] [Green Version] - Natural Resources Canada. Photovoltaic Potential and Solar Resource Maps of Canada. Available online: https://www.nrcan.gc.ca/our-natural-resources/energy-sources-distribution/renewable-energy/solar-photovoltaic-energy/tools-solar-photovoltaic-energy/photovoltaic-potential-and-solar-resource-maps-canada/18366 (accessed on 5 October 2021).

**Figure 1.**Diagram showing how building energy upgrades can make electricity available to the utility who redirects it for decarbonization applications and for the building itself (self-consumption).

**Figure 2.**Schematic showing the two modeled houses [7]: (

**a**) single-story existing house; (

**b**) two two-story solar houses built on the same land lot (they can be semi-detached or spaced with a small distance).

**Figure 4.**Monthly electricity freed up due to efficiency measures (blue line), solar electricity generation (red line), and total electricity that is made available by (green line): (

**a**) a house retrofit; (

**b**) rebuilding a house.

**Figure 5.**Generic energy profile produced by upgrading to a low-energy solar building showing the portions available for mobility and heating decarbonization.

**Figure 6.**Energy profile that is made available for mobility and heating decarbonization by upgrading to: (

**a**) a retrofitted house and (

**b**) a rebuilt house.

**Figure 7.**Monthly electricity available to decarbonize heating compared to the electricity consumption of the greenhouse (based on the area determined in Table 5) for: (

**a**) a retrofitted house; (

**b**) a rebuilt house.

**Figure 8.**Daily profile of power that is made available in winter and summer by replacing an existing house with a low-energy solar house.

**Table 1.**Energy performance of the existing, retrofitted, and rebuilt houses (values are based on 140 m

^{2}of living area for all three houses).

Month | Average Exterior Air Temperature (°C) | Existing House Total Energy Use (kWh m^{−2}) | Retrofit | Rebuild | ||
---|---|---|---|---|---|---|

Total Energy Use (kWh m^{−2}) | Solar Electricity Generation (kWh m^{−2}) | Total Energy Use (kWh m^{−2}) | Solar Electricity Generation (kWh m^{−2}) | |||

January | −10.1 | 29 | 11 | 14 | 10 | 7 |

February | −8.8 | 24 | 8 | 18 | 7 | 9 |

March | −2.2 | 19 | 5 | 24 | 5 | 11 |

April | 5.8 | 11 | 4 | 21 | 3 | 10 |

May | 13.3 | 7 | 3 | 24 | 3 | 11 |

June | 17.9 | 6 | 3 | 23 | 3 | 11 |

July | 21.1 | 6 | 4 | 24 | 4 | 11 |

August | 19.6 | 5 | 4 | 21 | 4 | 10 |

September | 14.6 | 6 | 3 | 21 | 3 | 10 |

October | 8.5 | 9 | 3 | 16 | 3 | 7 |

November | 1.9 | 15 | 4 | 8 | 4 | 4 |

December | −6.8 | 26 | 8 | 10 | 7 | 5 |

Total | 6.3 | 161 | 60 | 224 | 56 | 106 |

Month | Heating Energy (kWh m^{−2}) | Lighting Energy (kWh m^{−2}) | Other Energy (kWh m^{−2}) | Total Energy (kWh m^{−2}) |
---|---|---|---|---|

January | 125 | 43 | 2 | 170 |

February | 120 | 14 | 2 | 137 |

March | 99 | 5 | 2 | 106 |

April | 55 | 4 | 2 | 62 |

May | 28 | 3 | 3 | 33 |

June | 13 | 1 | 4 | 18 |

July | 6 | 2 | 5 | 12 |

August | 9 | 4 | 4 | 17 |

September | 22 | 6 | 3 | 31 |

October | 45 | 23 | 2 | 70 |

November | 63 | 48 | 2 | 113 |

December | 100 | 53 | 2 | 156 |

Total energy (kWh m^{−2} year^{−1}) | 684 | 206 | 34 | 925 |

Peak power demand (kW m^{−2}) | 0.28 | 0.22 | 0.003 | 0.50 |

**Table 4.**Energy and peak power that is made available from retrofitting/rebuilding a single-detached house.

Item | Existing | Retrofit | Rebuild |
---|---|---|---|

House energy use (kWh year^{−1}) | 22,557 | 8435 | 7846 |

Energy freed up due to efficiency (kWh year^{−1}) | - | 14,122 | 14,711 |

Solar energy generation (kWh year^{−1}) | - | 31,323 | 14,793 |

Total energy made available due to upgrade (kWh year^{−1}) | - | 45,445 | 29,504 |

Fraction of energy provided by efficiency measures | - | 31% | 50% |

Fraction of energy made available that is from PV | - | 69% | 50% |

Power made available due to efficiency measures (kW) | - | 7.1 | 7.3 |

**Table 5.**Greenhouse (GH) area that can be decarbonized/operated using the energy that is made available from retrofitting/rebuilding a single-detached house.

Item | Retrofit | Rebuild | ||
---|---|---|---|---|

Analysis for Electrifying Heating in Existing Greenhouses | Analysis for the Energy Needs of New Greenhouses | Analysis for Electrifying Heating in Existing Greenhouses | Analysis for the Energy Needs of New Greenhouses | |

Energy made available by upgrading a house (E_{decarb} kWh year^{−1}) | 45,445 | 45,445 | 29,505 | 29,505 |

Freed up power due to efficiency measures (P_{eff} kW) | 7.1 | 7.1 | 7.3 | 7.3 |

Average power reserved for EV (P_{EV} kW) | 3.6 | 3.6 | 2.3 | 2.3 |

Peak power available for GH (P_{max} kW) | 3.5 | 3.5 | 5 | 5 |

GH peak load (P_{GH} kW m^{−2}) | 0.28 | 0.5 | 0.28 | 0.5 |

GH area possible based on peak demand (A_{GH_per_house} m^{2}) | 12.5 | 7 | 18 | 10.1 |

GH area possible based on energy availability (A_{GH_per_house} m^{2}) | 19.8 | 14.6 | 14.1 | 10.4 |

GH design based on: energy or peak? | peak | peak | energy | peak |

Electricity use for GH heating (kWh year^{−1}) | 8555 | 4791 | 9650 | 6912 |

Other electricity used for GH (kWh year^{−1}) | N/A | 1681 | N/A | 2426 |

Fraction of total energy available consumed for GH | 19% | 14% | 33% | 32% |

Electricity leftover for other decarbonization (kWh year^{−1}) | 4973 | 7056 | 31 | 343 |

Fraction of total energy available for other | 11% | 16% | 0.1% | 1.2% |

**Table 6.**Energy that is provided by upgrading enough houses to achieve greenhouse (GH) crop production autonomy (scenario 1) and all houses heated by electric resistance (scenario 2).

Item | Scenario 1 | Scenario 2 | ||
---|---|---|---|---|

Retrofit | Rebuild | Retrofit | Rebuild | |

House upgrades needed to electrify heating in existing GH (N_{houses_GH_exist}) | 102,000 | 90,000 | 102,000 | 90,000 |

Houses upgrades needed to operate new GH (N_{houses_GH_new}) | 183,000 | 126,000 | 183,000 | 126,000 |

Other houses to be upgraded in scenario 2 (N_{houses_added}) | N/A | N/A | 449,000 | 518,000 |

Total houses to be upgraded (N_{houses_GH_tot} or N_{houses_tot2}) | 285,000 | 216,000 | 734,000 | 734,000 |

Fraction of total single-detached homes upgraded (F_{upgraded}) | 16% | 12% | 42% | 42% |

Energy that is made available for GH (E_{GH_tot} TWh year^{−1}) | 2.1 | 2.1 | 2.1 | 2.1 |

Energy that is made available for EV (E_{EV_tot} TWh year^{−1}) | 9.1 | 4.3 | 23.4 | 14.6 |

Energy leftover for other decarbonization (E_{leftover} TWh year^{−1}) | 1.8 | 0 | 7.9 | 5.1 |

Total energy available from upgraded homes (E_{decarb_tot} TWh year^{−1}) | 13 | 6.4 | 33.4 | 21.8 |

Fraction of Quebec total electricity use made available (F_{decarb}) | 7% | 4% | 19% | 12% |

**Table 7.**Number of personal EVs that can be operated using the energy that is made available from retrofitting/rebuilding a single-detached house.

Item | Retrofit | Rebuild |
---|---|---|

Monthly energy reserved for EVs (E_{EV} kWh month^{−1}) | 2660 | 1652 |

Annual energy for EVs (12 E_{EV} kWh year^{−1}) | 31,917 | 19,824 |

Fraction of house upgrade energy that is consumed for EVs | 70% | 67% |

Travel distance for BEV (D_{BEV} km year^{−1}) | 145,078 | 90,107 |

Travel distance for FCEV (D_{FCEV} km year^{−1}) | 61,379 | 38,122 |

Number of BEVs powered by one house upgrade (N_{BEV}) | 9.8 | 6.1 |

Number of FCEVs powered by one house upgrade (N_{FCEV}) | 4.1 | 2.6 |

**Table 8.**Mobility electrification that can be achieved by upgrading enough houses for greenhouse crop production autonomy (scenario 1) and by upgrading all houses that employ electric resistance heating (scenario 2).

Scenario 1 | Scenario 2 | |||
---|---|---|---|---|

Retrofit | Rebuild | Retrofit | Rebuild | |

Fraction of total single detached homes upgraded (F_{upgraded}) | 16% | 12% | 42% | 42% |

Energy available for EV (E_{EV_tot} TWh year^{−1}) | 9.1 | 4.3 | 23.4 | 14.6 |

Number of BEVs (N_{EV_tot}) | 2,793,735 | 1,315,082 | 7,195,092 | 4,468,843 |

Number of FCEVs (N_{FCEV_tot}) | 1,181,965 | 556,381 | 3,044,077 | 1,890,664 |

Fraction of total personal vehicles replaced with BEV (F_{EV_tot}) | 52% | 24% | 133% | 83% |

Fraction of total personal vehicles replaced with FCEV (N_{FCEV_tot}) | 22% | 10% | 56% | 35% |

**Table 9.**GHG emission reductions, embodied emissions, and payback time associated with upgrading enough single-detached houses to achieve greenhouse (GH) crop production autonomy (scenario 1) and all houses that employ electric resistance heating (scenario 2).

Scenario 1 | Scenario 2 | |||
---|---|---|---|---|

Retrofit | Rebuild | Retrofit | Rebuild | |

Fraction of total single-detached homes upgraded (F_{upgraded}) | 16% | 12% | 42% | 42% |

Reduction in GHG emissions | ||||

By converting personal vehicles to BEVs (GHG_{BEV} MtCO_{2eq}) | 9.5 | 4.5 | 20.7 | 15.2 |

By converting personal vehicles to FCEVs (GHG_{FCEV} MtCO_{2eq}) | 4 | 1.9 | 10.4 | 6.4 |

By electrifying GH heating (GHG_{GH} MtCO_{2eq}) | 0.3 | 0.3 | 0.3 | 0.3 |

By electrifying heating in other buildings (GHG_{leftover} MtCO_{2eq}) | 1.2 | 0 | 5.4 | 3.5 |

Total for BEV option (GHG_{tot} MtCO_{2eq}) | 11.1 | 4.8 | 26.5 | 19 |

Percent reduction in total GHG emissions (for BEV option) | 14% | 6% | 32% | 23% |

Total for FCEV option (GHG_{tot} MtCO_{2eq}) | 5.6 | 2.2 | 16.1 | 10.2 |

Percent reduction in total GHG emissions (for FCEV option) | 7% | 3% | 20% | 12% |

Embodied GHG emissions | ||||

For house retrofit/rebuild (EE_{houses} MtCO_{2eq}) | 4.8 | 18.1 | 12.3 | 61.7 |

For PV system (EE_{PV} MtCO_{2eq}) | 8.4 | 3 | 21.5 | 10.2 |

For production of BEV (EE_{BEVs} MtCO_{2eq}) | 27.7 | 13 | 56.1 | 44.2 |

For production of FCEV (EE_{FCEVs} MtCO_{2eq}) | 8.7 | 4.1 | 22.5 | 14 |

GHG emissions payback time | ||||

For the BEV option (PT_{GHG} yr) | 3.7 | 7.1 | 3.4 | 6.1 |

For the FCEV option (PT_{GHG} yr) | 3.9 | 11.2 | 3.5 | 8.4 |

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**MDPI and ACS Style**

Bambara, J.; Athienitis, A.K.; Eicker, U.
Decarbonizing Local Mobility and Greenhouse Agriculture through Residential Building Energy Upgrades: A Case Study for Québec. *Energies* **2021**, *14*, 6820.
https://doi.org/10.3390/en14206820

**AMA Style**

Bambara J, Athienitis AK, Eicker U.
Decarbonizing Local Mobility and Greenhouse Agriculture through Residential Building Energy Upgrades: A Case Study for Québec. *Energies*. 2021; 14(20):6820.
https://doi.org/10.3390/en14206820

**Chicago/Turabian Style**

Bambara, James, Andreas K. Athienitis, and Ursula Eicker.
2021. "Decarbonizing Local Mobility and Greenhouse Agriculture through Residential Building Energy Upgrades: A Case Study for Québec" *Energies* 14, no. 20: 6820.
https://doi.org/10.3390/en14206820