Author: EcofuturistUK

Overview

At the end of 2014, the petrol hybrid vehicle was changed for a full battery electric vehicle (BEV), the Nissan Leaf (24kWh battery capacity), to further reduce travel emissions and eliminate tailpipe emissions completely. Electric vehicles are also an essential part of the sustainable energy transition, providing the storage of excess wind power generation, and reducing its curtailment as more is added to the grid system.

This 2^nd generation of the first mass produced full BEV had a range of 90 miles on one charge. Although this range was low, crucially it enabled me to travel more miles at less cost with lower emissions. At the dwelling, the vehicle was charged on an economy seven tariff, ensuring lower cost, and charging during off-peak time at night when grid electricity is greener. The carbon fingerprint is shown in Fig.1. in comparison with previous years and baseline. 

Fig.1. The fingerprint of CO₂e emissions in 2015, in comparison with previous years and baseline.

Solar Power Generation

The total solar power generation for the year increased slightly by 20 kWh to 1613 kWh, derived from reading the generation meter. The monthly solar generation data are shown in Fig.2.

Fig.2. Monthly solar generation data.

Household Electricity Consumption

Total annual household electricity grid consumption increased on the previous year by 345 kWh or 32% to 1427 kWh, again derived from reading the electricity meter. The monthly grid electricity consumption data are shown in Fig.3.

Fig.3. Monthly grid electricity consumption data.

Using the assumption of 25% solar self-consumption, 1427 kWh grid consumption minus 1210 kWh solar export resulted in a net grid electricity consumption of 217 kWh. Grid electricity was given a carbon intensity figure of 0.5 kgCO₂e/kWh (DECC, 2015) for a 2015 generation mix. This resulted in an emission increase of 170 kgCO₂e to 109 kgCO₂e or 0.1 tCO₂e.

Space and Water Heating

Total annual household gas consumption increased by 21% to a more typical level of 4922 kWh, compared to the previous year’s low, derived from monthly meter readings, shown as a column chart in Fig.4. All consumption was provided by the gas grid, and given a carbon intensity figure of 0.205 kgCO₂e/kWh (DECC, 2015). This resulted in an increase of 172kgCO₂e to 1009 kgCO₂e or 1.0 tCO₂e emissions.

Fig.4. Monthly gas consumption data.

Car Travel

Fig.5. The Battery Electric Nissan Leaf.

The car in use was now a battery electric vehicle (BEV), shown in Fig.5. The annual mileage had also increased by 50% in this year, and estimated to the nearest 1000 was given as 12000 miles, or 19000 km. As the fuel is electricity, the carbon intensity figure of fuel production and use in an electric vehicle is the same as is given for grid electricity, which this year was 0.5 kgCO₂e/kWh (DECC, 2015) for a 2015 generation mix. The car consumed 2500 kWh of electricity to charge, derived from monthly readings of the night time consumption meter and shown as a column chart in Fig.6. This resulted in fuel production emissions only, and a reduction of 31% or 570 kgCO₂e to 1250 kgCO₂e or 1.3 tCO₂e.

Notes: Had the mileage remained at 8000 miles, the emission value would have been reduced by 54% to 833 kgCO₂e. In the units previously given for vehicle emissions, 2015 grid electricity equates to 0.066 kgCO₂e/km.

Fig.6. Monthly car charging data.

Water Consumption

Total annual household water consumption increased by 33% to 32 m³, derived from a utility bill for that year. The 2015 carbon intensity figure of domestic water supply (0.344 kgCO₂e/m³), and treatment (0.709 kgCO₂e/m³) is given as 1.053 kgCO₂e/m³ (DECC, 2015). This resulted in an emission increase of 9 kgCO₂e to 34 kgCO₂e, holding the fingerprint value at 0.03 tCO₂e.

Lifestyle

The energy supplier was changed to a different 100% renewable generator, Ecotricity. This provided a better tariff for charging the BEV, and enabled investment in a green bond to fund building of new renewable generation assets like wind and solar farms. A further investment was made in Thrive Renewables for the same reason. These did not affect the results for lifestyle in the carbon footprint calculator (WWF, 2016), so emissions remained at 0.5 tCO₂.

Infrastructure

The figure for infrastructure emissions in the carbon footprint calculator (WWF, 2016) remained at 2.75 tCO₂ for each UK citizen. The annual donation to the Woodland Trust to plant 25 m² of woodland, and the 12 trees planted off-set and sequester -1.12 tCO₂ of these indirect emissions.

Behaviours

The travel mileage had increased as more time was spent away from home on work placements. Household electricity use increased, possibly due to less time available to use solar power for clothes and dishwashing due to being out during the daytime, and some unintended charging of the EV outside of the off-peak period.

Conclusions

There was an overall emissions reduction of 2% or 0.1 tCO₂e compared to the previous year, and 57% or 6.1 tCO₂e compared to the baseline year. This was mostly due to the reduction in travel emissions of 0.5 tCO₂e, however this reduction was limited by a 50% increase in vehicle mileage, and increases in grid electricity use and gas consumption emissions both of 0.2 tCO₂e. There was a further, slight increase in water use, which does not show in the fingerprint. 

References

The Department for Energy and Climate Change (2015). Greenhouse gas reporting – Conversion factors 2015. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2015 (accessed 05 August 2016).

WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).

Overview

I graduated this year from the Open University with a BSc Environmental Studies and Diploma in Environmental Policy, as a mature student aged 40. Over the previous three years, the action taken to reduce carbon dioxide emissions in the four main areas of electricity use, space heating and hot water, travel, and lifestyle, resulted in an annual reduction of 43% or 4.6 tCO₂e. However, whilst good progress had been made in reducing these direct emissions, there remained a substantial contribution to the footprint from the indirect emissions from infrastructure. These emissions could only be reduced by off-setting, and so it was decided to increase the contribution of natural carbon capture and storage, or sequestration, through planting a further six trees at home and donating money each year to plant a further 25 m² of woodland. The carbon fingerprint is shown in Fig.1. in comparison with previous years and baseline. 

Fig.1. The fingerprint of CO₂e emissions in 2014, in comparison with previous years and baseline.

Solar Power Generation

The total solar power generation for the year increased slightly by 16 kWh to 1593 kWh, derived from reading the generation meter. The monthly solar generation data are shown in Fig.2.

 Fig.2. Monthly solar generation data.

Household Electricity Consumption

Total annual household electricity grid consumption was reduced on the previous year by 20% or 271 kWh to 1082 kWh, again derived from reading the electricity meter. The monthly grid electricity consumption data are shown in Fig.3.

Fig.3. Monthly grid electricity consumption data.

Using the assumption of 25% solar self-consumption, this year 1082 kWh grid consumption minus 1195 kWh solar export resulted in a net grid electricity export of 113 kWh. Grid electricity was given a carbon intensity figure of 0.537 kgCO₂e/kWh (DECC, 2014) for a 2014 generation mix. The combined solar self-consumption and exported generation resulted in an emissions reduction on the previous year of 144 kgCO₂e to -61 kgCO₂e or -0.1 tCO₂e.

Space and Water Heating

Due to very mild winter weather conditions, total annual household gas consumption decreased by 20% on the previous year to 4065 kWh, the lowest value so far, derived from monthly meter readings, shown as a column chart in Fig.4. All consumption was provided by the gas grid, and given a carbon intensity figure of 0.206 kgCO₂e/kWh (DECC, 2014). This resulted in a decrease of 210kgCO₂e to 837 kgCO₂e or 0.8 tCO₂e emissions.

Fig.4. Monthly gas consumption data.

Car Travel

The vehicle in use remained a mid-sized 1.6 litre petrol hybrid. The estimated annual mileage to the nearest 1000 was given as 8000 miles, or 13000 km. The carbon intensity figure of petrol fuel production and use in a hybrid vehicle is given as 0.14 kgCO₂e/km (DECC, 2012). This resulted in emissions remaining at 1.8 tCO₂e.

Water Consumption

A 300-litre water butt was installed to collect rainwater from the main house roof for later use in the garden, and watering houseplants. Total annual household water consumption was reduced by 11% to 24 m³, derived from a utility bill for that year. The 2014 carbon intensity figure of domestic water supply (0.344 kgCO₂e/m³), and treatment (0.709 kgCO₂e/m³) is given as 1.053 kgCO₂e/m³ (DECC, 2014). This resulted in an emissions reduction of 3 kgCO₂e to 25 kgCO₂e, holding the fingerprint value at 0.03 tCO₂e.

Lifestyle

An extremely inefficient LCD television was replaced with a more efficient LED TV at the beginning of this year. The new TV was Ten-times more efficient, reducing the power output from 350 Watts to just 35 Watts. This was the likely reason for the 20% reduction in grid electricity demand. The old TV was sold to a second-hand store.

My savings were moved to ethical bank Triodos, to ensure my money was only being invested in environmentally and socially positive, sustainable projects. I also became a member and supporter of the Centre for Alternative Technology in Machynlleth, Wales.

These did not affect the results for lifestyle in the carbon footprint calculator (WWF, 2016), so emissions remained at 0.5 tCO₂.

Infrastructure

The figure for infrastructure emissions in the carbon footprint calculator (WWF, 2016) remained at 2.75 tCO₂ for each UK citizen. Six more trees were planted, some are shown in Fig.5., and money donated annually to the Woodland Trust to plant 25 m² of woodland to off-set a further 1.06 tCO₂ of these infrastructure emissions. Together with the 0.06 tCO₂ sequestered each year by the six trees planted in 2011, this resulted in sequestration of -1.12 tCO₂ in the fingerprint. This action also has an additional positive effect by increasing biodiversity.

Fig.5. Four of the six newly planted trees. (Clockwise from left) Rowan, Silver Birch, Oak, and Field Maple.

Behaviours

With a new understanding of the electricity grid and my solar generation, I began to change behaviour around electricity use. Making the most of the solar generation by doing clothes washing and using the dishwasher when the solar PV system was producing peak power. I also began delaying cooking my evening meals until 7.30 pm. This reduces carbon emissions by reducing the amount of fossil-fuelled power needed to meet the evening peak electricity demand between 4pm and 7.30pm.

Conclusions

There was an overall emissions reduction of 23% or 1.4 tCO₂e compared to the previous year, and 56% or 6 tCO₂e compared to the baseline year. This was mostly due to off-set infrastructure emissions of 1.06 tCO₂e by natural sequestration from tree planting. Contributions also came from net grid electricity export, and a weather-related decrease in gas consumption further reducing emissions by 0.1 tCO₂e and 0.2 tCO₂e, respectively. There was a further, slight reduction in water use which does not show in the fingerprint. 

References

The Department for Energy and Climate Change (2014). Greenhouse gas reporting – Conversion factors 2014. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2014 (accessed 05 August 2016).

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 6d. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).

Overview

With a 41% reduction in carbon emissions per year already achieved from space and water heating, car use, and electrical efficiency, the focus turned to reducing electrical demand from the grid. With the help of a government incentive, the Feed-in-Tariff (FiT), it became financially viable to install a solar system. In November 2012, a 1.8 kWp (kiloWattpeak) solar photovoltaic array was installed on the south-east facing roof of the property, consisting of eight 230-Watt polycrystalline silicon modules. The system was predicted by the installer to produce 1472 kWh of zero-carbon electricity per year, of which approximately one-quarter would be self-consumed, and the rest exported to the grid.

Further improvements to thermal efficiency were also made in September of this year, in the form of A-rated, argon-filled, double-glazed windows with a low emissivity coating which traps heat in and maximises passive solar gain. The carbon fingerprint is shown in Fig.1. in comparison with previous years and baseline. 

Fig.1. The fingerprint of CO₂e emissions in 2013, in comparison with previous years and baseline.

Solar Power Generation

The solar array, shown in Fig.2., reached the predicted generation value on September 22^nd, with a full quarter of the year still to go. The total generation for the year was 1577 kWh, derived from reading the generation meter. The monthly solar generation data are shown in Fig.3.

Fig.2. The 1.8 kWp Solar Photovoltaic rooftop array on my home.

Fig.3. Monthly solar generation data.

Furthermore, the solar PV system installation improved the Energy Performance Certificate (EPC) value from Band C (Rating 73) to Band B (Rating 83), shown in Fig.4.

Fig.4. A draft EPC showing the new current energy efficiency rating of the building.

Household Electricity Consumption

Total annual household electricity grid consumption was reduced on the previous year by 23% or 403 kWh to 1353 kWh, again derived from reading the electricity meter. The monthly grid electricity consumption data are shown in Fig.5. However, a new approach was now needed to work out the CO₂e emissions.

Fig.5. Monthly grid electricity consumption data.

The methodology to determine the net CO₂e emissions from electricity use is worked as follows, using the data from this first year of solar generation. The predicted solar self-consumption of 25% of total generation would be 394 kWh, very close to the electricity grid consumption reduction of 403 kWh. Working on the assumptions that overall household electrical demand was similar, but slightly lower, to the previous year, and all electricity grid consumption reduction was a result of solar generation, this then leaves 75% or 1183 kWh of solar generation exported to the grid. This exported generation removes the equivalent amount having to be generated by the electricity grid, off-setting household electricity consumed from the grid, at night for example.

This year, 1353 kWh consumed minus 1183 kWh exported resulted in a net grid electricity consumption of 170 kWh. Grid electricity was given a carbon intensity figure of 0.484 kgCO₂e/kWh (DECC, 2013) for a 2013 generation mix. The combined solar self-consumption and exported generation resulted in a 91% emissions reduction compared to the previous pre-solar year of 789 kgCO₂e to 82 kgCO₂e or 0.1 tCO₂e.

Note: This is a very simplified method, and is used because the data sources i.e., meter readings, are very basic. It is however, considered appropriate for the illustrative purposes and scope of this work.

Space and Water Heating

Due to colder winter weather conditions, total annual household gas consumption increased by 17% on the previous year to 5081 kWh, derived from monthly meter readings, despite the thermal improvement of the glazing. The monthly gas consumption data are shown as a column chart in Fig.6., and the effect of the new windows can be seen in the lower gas consumption during the winter months at year end when compared to those at the beginning of the year. All consumption was provided by the gas grid, and given a carbon intensity figure of 0.206 kgCO₂e/kWh (DECC, 2012). This resulted in an increase of 153kgCO₂e to 1047 kgCO₂e or 1.0 tCO₂e emissions.

Fig.6. Monthly gas consumption data.

Car Travel

The vehicle in use remained a mid-sized 1.6 litre petrol hybrid. The estimated annual mileage to the nearest 1000 was given as 8000 miles, or 13000 km. The carbon intensity figure of petrol fuel production and use in a hybrid vehicle is given as 0.14 kgCO₂e/km (DECC, 2012). This resulted in emissions remaining at 1.8 tCO₂e.

Water Consumption

Total annual household water consumption was reduced by 16% to 27 m³, derived from a utility bill for that year. The 2012 carbon intensity figure of domestic water supply (0.344 kgCO₂e/m³), and treatment (0.709 kgCO₂e/m³) is given as 1.053 kgCO₂e/m³ (DECC, 2013). This resulted in a reduction of 6 kgCO₂e to 28 kgCO₂e, holding the fingerprint value at 0.03 tCO₂e emissions.

Lifestyle

The firm providing energy to the home was changed at the beginning of the year, from one of the ‘big six’ to one of the two 100% renewable energy providers in the UK, Good Energy. They would also provide the FiT payments for solar power generation. Although it is a better lifestyle choice to support the building of new renewable energy sources through supporting these suppliers, this did not affect the results for lifestyle in the carbon footprint calculator (WWF, 2016), so emissions remained at 0.5 tCO₂.

Infrastructure

The figure for infrastructure emissions in the carbon footprint calculator (WWF, 2016) remained at 2.75 tCO₂ for each UK citizen. Again, a value of -0.06 tCO₂ was attributed to the natural sequestration of CO₂ by the six trees planted in 2011.

Behaviours

Beginning this year, meter readings were now being taken monthly and logged, for solar generation, electricity grid consumption and gas consumption.

Conclusions

There was an overall emissions reduction of 10% or 0.7 tCO₂e compared to the previous year, and 43% or 4.6 tCO₂e compared to the baseline year. This was exclusively due to reduced emissions of 0.8 tCO₂e from net grid electricity consumption, because of solar power generation. A slight weather-related increase in gas consumption reduced the margin by 0.1 tCO₂e. There was a further, slight reduction in water use, and a CO₂ reducing lifestyle choice that do not show in the footprint. 

Importantly, the change to a 100% renewable energy supplier was not used to give a zero-emission factor for electricity grid consumption in the footprint. It was decided, using the yearly emission factors of the mix of generation provided a true representation of CO₂ emissions in this category.

References

The Department for Energy and Climate Change (2013). Greenhouse gas reporting – Conversion factors 2013. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2013 (accessed 05 August 2016)

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 6d. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).

Overview

The measures implemented by the end of 2011 are achievable in most homes, especially with funding from government, and this demonstrates that just implementing the less expensive measures can achieve a 20% reduction in carbon emissions. To put this in context, the UK national carbon emission reduction target by 2020 under the Kyoto protocol and EU emission target was 20% below the 1990 baseline year (UNFCCC, 2012).

However, the carbon fingerprint highlights there were further reductions to be made. With the lowest cost measures having been taken to reduce emissions from the property, with significant effect, it was time to focus on reducing travel emissions. The carbon fingerprint is shown in Fig.1. in comparison with the previous year and baseline. 

Fig.1. The fingerprint of CO₂e emissions in 2012, in comparison with the previous year and baseline.

Household Electricity Consumption

Total annual household electricity consumption slightly increased on the previous year by 1% to 1756 kWh, derived from a utility bill for that year. All consumption was provided by the electricity grid and given a carbon intensity figure of 0.496 kgCO₂e/kWh (DECC, 2013) for a 2012 generation mix. This resulted in an increase of 17 kgCO₂e to 871 kgCO₂e, holding the fingerprint value at 0.9 tCO₂e emissions.

Space and Water Heating

No further improvements to thermal efficiency were made this year. However, due to milder winter weather conditions and less hot water demand, total annual household gas consumption was reduced by 29% on the previous year to 4342 kWh, derived from a utility bill for that year. All consumption was provided by the gas grid and given a carbon intensity figure of 0.206 kgCO₂e/kWh (DECC, 2012). This resulted in a reduction of 368 kgCO₂e to 894 kgCO₂e or 0.9 tCO₂e emissions.

An Energy Performance Certificate (EPC) survey was undertaken in October of this year to provide a value of energy performance for the building. This was needed in preparation for a solar PV system installation. The result was a value of Band C (Rating 73), shown in Fig.2.

Fig.2. The EPC showing the current energy efficiency rating of the building.

Car Travel

At the end of 2011, the vehicle in use was changed to a mid-sized 1.6 litre petrol hybrid, pictured in Fig.3. With the new breed of battery electric vehicles still in their infancy, and prohibitively expensive, this was the best option at the time. The estimated annual mileage to the nearest 1000 was given as 8000 miles, or 13000 km. The carbon intensity figure of petrol fuel production and use in a hybrid vehicle is given as 0.14 kgCO₂e/km (DECC, 2012). This resulted in a 44% reduction of 1417 kgCO₂e to 1820 kgCO₂e or 1.8 tCO₂e emissions.

Fig.3. Myself with the Toyota Auris petrol hybrid car.

Water Consumption

This year a water meter was installed at the property. Total annual household water consumption was reduced by 16% to 32 m³, derived from a utility bill for that year. The 2012 carbon intensity figure of domestic water supply (0.344 kgCO₂e/m³), and treatment (0.709 kgCO₂e/m³) is given as 1.053 kgCO₂e/m³ (DECC, 2013). This resulted in a reduction of 6 kgCO₂e to 34 kgCO₂e or 0.03 tCO₂e emissions.

Lifestyle

There were no changes to the previous year, so emissions remained at 0.5 tCO₂.

Infrastructure

The figure for infrastructure emissions in the carbon footprint calculator (WWF, 2016) remained at 2.75 tCO₂ for each UK citizen, and a value of -0.06 tCO₂ was attributed to the natural sequestration of CO₂ by the six trees planted in 2011.

Behaviours

Occupancy remained the same as the previous year, however more vigilance was observed with water use, with the installation of the water meter. This clearly reduced water use, but also reduced gas consumption for water heating, as showers were now taken more often than a bath.

Conclusions

There was an overall emissions reduction of 21% or 1.8 tCO₂e compared to the previous year, and 41% or 3.9 tCO₂e compared to the baseline year. This was primarily due to reduced car-fuel consumption, from the decreased emission factor in the production and use of petrol in a hybrid drivetrain vehicle. The difference between a two-litre petrol car compared to a 1.6 litre hybrid car was an impressive 1.4 tCO₂e/year when driving the same mileage. There was a further contribution from reduced gas consumption, although this was mostly weather related, and another small contribution from reduced water use.

References

The Department for Energy and Climate Change (2013). Greenhouse gas reporting – Conversion factors 2012. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2012

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 6d. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).

UNFCCC (2012). Doha Amendment to The Kyoto Protocol Doha, 8 December 2012. Available at: Microsoft Word – wtp1356369662324.doc (un.org) (accessed 04 November 2022).

Overview

In 2005, before consciously reducing my carbon footprint, the house was extensively refurbished. The front and patio doors were replaced with new standard PVCu units with thermal values of the time, the side door was removed and bricked up, the flat roof extension roof was replaced, re-insulated and covered with a rubber membrane, the loft was insulated to 150 mm with wool fibre and the old inefficient boiler was replaced with a 90% efficient gas condensing boiler, new pipework, and radiators. This improved the thermal efficiency of the building when compared to the baseline year. The electrics were rewired and there were also new electrical additions in the form of a desktop PC and a dishwasher, and an old washing machine was replaced.

In 2011, the first low-cost measures were introduced to further improve the thermal efficiency of the building and its energy and water consumption. The carbon fingerprint is shown in Fig.1. in comparison to the baseline. 

Fig.1. The fingerprint of CO₂e emissions in 2011, in comparison with the baseline.

Household Electricity Consumption

Initially, an energy monitor was used to find where consumption could be reduced. LED bulbs were installed throughout the house which use 90% less power than the incandescent or halogen bulbs they replaced. Investments were made in an eco-kettle which can boil just a single cup, and a slow cooker. Effort was also made to ensure appliances were never left on standby.

Total annual household electricity consumption was slightly reduced by 2% to 1739 kWh, derived from a utility bill for that year. All consumption was provided by the electricity grid and given a carbon intensity figure of 0.491 kgCO₂e/kWh (DECC, 2013) for a 2011 generation mix. This resulted in a reduction of 65 kgCO₂e to 854 kgCO₂e, holding the fingerprint value at 0.9 tCO₂e emissions.

Space and Water Heating

To further reduce building fabric heat loss, loft insulation was increased to 300 mm with wool fibre, and cavity wall insulation was installed. Areas where air was escaping, gaps under skirting boards for example, were also sealed. Importantly, the insulation was funded by a Welsh Government grant available at the time, which was much appreciated.

These measures reduced total annual household gas consumption by 61% to 6127 kWh, again derived from a utility bill for that year. All consumption was provided by the gas grid and given a carbon intensity figure of 0.206 kgCO₂e/kWh (DECC, 2012). This resulted in a reduction of 1973 kgCO₂e to 1262 kgCO₂e or 1.3 tCO₂e emissions.

Car Travel

The vehicle in use was a mid-sized 2.0 litre petrol. The estimated annual mileage to the nearest 1000 was given as 8000 miles, or 13000 km. The carbon intensity figure of petrol fuel production and use is given as 0.249 kgCO₂e/km (DECC, 2012). This resulted in a 15% increase of 468 kgCO₂e to 3237 kgCO₂e or 3.2 tCO₂e emissions.

Water Consumption

At this time there was no water meter installed at the property. Some low-flow gadgets were installed on taps, and hippos placed in the two toilet cisterns. Total annual household water consumption was reduced by 24% to 38 m³, again derived from a utility bill for that year. The 2011 carbon intensity figure of domestic water supply (0.344 kgCO₂e/m³), and treatment (0.709 kgCO₂e/m³) is given as 1.053 kgCO₂e/m³ (DECC, 2012). This resulted in a reduction of 8 kgCO₂e to 40 kgCO₂e or 0.04 tCO₂e emissions.

Lifestyle

Conscious changes to my lifestyle began in this year.  Food was top of the list, I removed red meat and reduced dairy in my diet, started buying organic, fresh, seasonal food from local farm shops where possible, and only sustainably caught fish. I started supporting environmental charities Greenpeace, and Friends of the Earth, already a supporter of RSPB, and made much more effort to live by the three R’s, Reduce, Re-use and Recycle.

These changes were put into the carbon footprint calculator (WWF, 2016), and a figure was given for a low consumption lifestyle but with some conscious decisions around ethics and low-impact diet. This resulted in a 50% reduction to 0.5 tCO₂ emissions.

Infrastructure

The figure for infrastructure emissions in the carbon footprint calculator (WWF, 2016) remained at 2.75 tCO₂ for each UK citizen. However, whilst these emissions cannot be controlled directly, they can be off set through the natural sequestration of CO₂ through tree planting. This year I planted six native trees in the garden. The principle I use is that, according to the Woodland Trust, each tree will absorb one ton of CO₂ during a 100-year lifetime, which gives a value of 10 kg per year, although trees absorb more CO₂ as they mature and less in the early years. This gives a value of -0.06 tCO₂ in the fingerprint.

Behaviours

By this year the house was occupied most of the time, whilst I studied by distance learning from home, in contrast to occupancy in the baseline year. Because of this, there was inevitably some ‘rebound effect,’ as some of the energy efficiencies made were absorbed by increased consumption patterns.

Conclusions

There was an overall emissions reduction of 20% or 2.1 tCO₂e compared to the baseline year. This mostly came from the greater efficiency of the heating system, but also thermal improvements to the building fabric, through insulation and improved airtightness, with smaller contributions from lifestyle choices and water use. Electricity consumption was also reduced however the reduction was small due to increases in consumption from more appliances and hours of occupancy. Furthermore, the reduction in emissions would have been greater but were countered by the increased emission factor in the production and use of petrol for car fuel compared to diesel.    

References

The Department for Energy and Climate Change (2013). Greenhouse gas reporting – Conversion factors 2011. Available at: Greenhouse gas reporting – Conversion factors 2011 – GOV.UK (www.gov.uk) (accessed 05 August 2016).

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 1d. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 6b. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 9a. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).

Overview

In 2010, I decided to begin making the transition from business-as-usual to a low-carbon, sustainable existence. It was then, and still remains, important to do this to try to mitigate the worst effects of human-caused climate change, the biggest threat to humanity and all life on Earth, to be part of the solution, and one less part of the problem. To achieve this, we can reduce the carbon dioxide emissions from our activities by focussing on four areas: space and water heating, electricity consumption, transport, and lifestyle. We can also reduce our impact on natural systems by reducing water use, planting trees, and increasing green space for biodiversity.

Setting a baseline

It would be nice to live in a zero-carbon eco-house, built for the purpose of living a reduced carbon-emitting lifestyle. However, the reality is that most of us will have to work with what we already have, in this case a 1960’s three-bedroom semi-detached house. The first step is to understand exactly what our energy usage is. This can be done through a combination of looking at old utility bills, and taking meter readings for electricity, gas, and water; the mpg consumption and annual mileage of a car; and using data from a carbon footprint calculator for lifestyle and infrastructure values. Through this process and using Carbon Dioxide (CO₂) emission factors from reliable sources, a representation of the CO₂ fingerprint and total footprint can be formed for a baseline year to measure improvements against, in my case this was 1998, shown in Fig.1.

Fig.1. The fingerprint of CO₂e emissions in the 1998 baseline year.

Notes:

The emission factors are given as kgCO₂e (kilograms carbon dioxide equivalent) which include emissions of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), except those from the WWF carbon footprint calculator.

The emission factors were updated, and WWF carbon footprint calculator values added in 2016.

Household Electricity Consumption

The lights in the house at that time used incandescent bulbs. Appliances were relatively new and had the efficiencies of their time. There was no home computer, tumble dryer, or dishwasher, but apart from those the home had all the usual electrical appliances needed for it to function. 

Total annual household electricity consumption was 1771 kWh (kiloWatt hours), derived from an old utility bill from that year. All consumption was provided by the electricity grid and given a carbon intensity figure of 0.519 kgCO₂e/kWh for a 1998 generation mix (DECC, 2012). This resulted in 919 kg or 0.9 tCO₂e emissions.

Space and Water Heating

This was provided by a 1970’s gas-fired central heating boiler and radiators, very inefficient by modern standards. This was also not a thermally efficient building. There was a thin 2 cm vermiculite insulation layer in the loft, no cavity wall insulation, 1980’s double-glazed aluminium framed windows and patio doors, and leaky wooden front and side doors. Hot water was provided by the boiler on demand.

Total annual household gas consumption was 15704 kWh, again derived from an old utility bill from that year. All consumption was provided by the gas grid and given a carbon intensity figure of 0.206 kgCO₂e/kWh (DECC, 2012). This resulted in 3235 kg or 3.2 tCO₂e emissions.

Car Travel

The vehicle in use was a mid-sized 1.9 litre diesel. The estimated annual mileage to the nearest 1000 was given as 8000 miles, or 13000 km. The carbon intensity figure of diesel fuel production and use is given as 0.213 kgCO₂e/km (DECC, 2012). This resulted in 2769 kg or 2.8 tCO₂e emissions.

Water Consumption

At this time there was no water meter installed at the property. Total annual household water consumption was 50 m³, again derived from an old utility bill from that year. The carbon intensity figure of domestic water supply (0.276 kgCO₂e/m³), and treatment (0.693 kgCO₂e/m³) is given as 0.969 kgCO₂e/m³ (DECC, 2012). This resulted in 48 kg or 0.05 tCO₂e emissions.

Note: These figures relate to 2007/2008, as the nearest year available.

Lifestyle

These emissions come from our lifestyle choices such as type, consumption, production, and origin of goods like clothes, devices, food and energy, and the ethics or Corporate Social Responsibility (CSR), also known as Environmental, Social and Governance (ESG) of companies we use to provide these.

This figure was derived from an online carbon footprint calculator by the World Wildlife Fund (WWF, 2016), whereby a figure is given depending on the inputs we give as to our lifestyle choices. More environmental and ethical choices give a lower score. A figure was given for a low consumption lifestyle but with few conscious decisions around ethics and low-impact diet. This resulted in 1 tCO₂ emissions.

Infrastructure

The infrastructure we use like services, roads, hospitals etc., also have CO₂ emissions attributed to them. The major difference with these emissions compared to the other components is that they are not personally controllable, and therefore remain constant over the monitoring period. Infrastructure processes are generally carbon intensive, with little room to reduce the associated emissions. They are attributed to everyone as a proportion of the total emissions for the whole of the UK. The figure was derived from the same carbon footprint calculator (WWF, 2016), and results in 2.75 tCO₂ for each UK citizen.

Behaviours

During the baseline year, occupancy was extremely low, with me being out at work for most of the day during the week, and at leisure at weekends. This resulted in very low consumption of electricity and gas for space heating. Flight emissions would have been considered here had any flights been taken, but none were in the baseline year or over the monitoring period. In fact, I have not taken any flights since 2001, but consciously none since 2010 due to the climate impacts.

Conclusions

The rounded total emissions figure of 11 tCO₂ for the baseline year is relatively low for a household. However, this household is single occupancy, and remains so right through the monitoring period. It is, therefore, more of an individual footprint in this case, but the methods apply to a household and can be used as such. The baseline highlights the areas for improvement, notably gas, car fuel and electricity consumption emissions, although all areas can and will be improved.

References

1. The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 3c. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

2. The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 1d. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

3. The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 6c. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

4. The Department for Energy and Climate Change and The Department for Environment, Food and Rural Affairs (2012). 2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting. Table 9a. Available at: pb13773-ghg-conversion-factors-2012.pdf (publishing.service.gov.uk) (accessed 05 August 2016).

5. WWF-UK (2016). Available at: WWF Footprint Calculator (accessed 05 August 2016).