the influence of consumer behaviour on the greenhouse gas...
TRANSCRIPT
Method
Functional Unit: One shower event
Technique: Monte Carlo Simulation
Calculation of “contribution to variance”:
- 2-Way Analysis of Variance for categorical variables
- Correlation coefficients for numerical variables
Main Input Variables:
- Consumer survey data
- Consumer’s reasoned choices (Heater type, energy efficiency, shower flow rate )
- Consumer habits (Shower duration, shower temperature, number and type of products, dosage)
- Country-specific factors (Cold water temperature, energy mix, water availability)
Impact assessment: GHG emissions, Water Scarcity (AWARE: Available Water Remaining method)
Countries: Australia (AU), Switzerland (CH), United Kingdom (UK), United States of America (US)
Objective
The objective of this study was to quantify the variability in life cycle GHG emissions and water
scarcity of domestic showering associated with consumer behaviour.
Results
Figure 4. Variability for each footprint indicator per water heater type, given the volume of water used in the shower.
Conclusions:
The Influence of Consumer Behaviour on the Greenhouse Gas and Water Footprints of Showering
Figure 1. Life cycle a) GHG emissions and b) water scarcity associated with one showering event. The box plots show 5th, 25th, 50th, 75th and 95th percentiles.
Figure 3. Variability in the footprints by contributor (P: products, WP&T: water provisioning and treatment, WH: water heating) and by country
Sadegh Shahmohammadi1, Zoran Steinmann1, Henry King2, Hilde Hendrickx2, Mark A.J. Huijbregts1
1Department of Environmental Science, Faculty of Science, Radboud University Nijmegen2Unilever R&D, Colworth Science Park, UK
This project has received funding from the European Union’s Horizon 2020 research andinnovation programme under the Marie Sklodowska-Curie grant agreement No 641459.
Figure 1:
➢ GHG emissions vary by a factor of 10 in the UK up to a factor of 17 in Switzerland (95th
percentile/5th percentile).➢ Inter-country variability (median country A/median country B) is a factor of 2 for GHG emissions
and is a factor of 5 for water scarcity.
Figure 2:
➢ Consumers’ reasoned choices are the dominant contributors to variance for GHG emissions in allcountries and for water scarcity footprints in Switzerland, the UK and the US.
➢ Consumer habits: shower duration (volume of heated water) contributes most to the variancecompared to shower temperature and product type and dosage.
Figure 2 continued:➢ Choice of water heater and shower flow rate are the major contributors to
variance among the one-off reasoned actions.
Figure 3:
➢ Water heating has a dominant contribution to the life cycle GHG emissions ofshowering in all countries.
➢ Water consumed for water provisioning and wastewater treatment has a majorcontribution to the water scarcity footprint except in Switzerland.
➢ Products (e.g. shampoo, shower gel, conditioner etc.) are key contributors to thelife cycle water scarcity footprint in Switzerland and in the UK.
✓Both consumer differences in reasoned choices –particularly water heater type-as well as differences in habitual behavior –shower duration in particular- have alarge influence on the variability in the environmental footprints of showering.
✓Significant savings can be achieved by using more sustainable sources of energyfor water heating and by taking shorter showers.
• Example: If all consumers in Australia switch to solar boosted water heaters, ourcalculations show 62% reduction in the life cycle GHG emissions and 12%reduction in water scarcity.
Figure 4: Variability by water heating type
➢ The footprints are highly related to:1. The volume of water used in the shower (Shower duration × Flow rate)2. The source of energy used by water heater (water heater type)3. The region where the shower event is performed.
➢ Electric water heaters have typically the highest footprints.➢ Solar boosted heaters and heat pumps greatly reduce the environmental footprints.
Figure 2. Contribution to variance associated with the output variables of the model (AU: Australia, CH: Switzerland, UK: United Kingdom, US: United States).
