Different parameters have been set to portray the degree of the audit with a particular objective of giving a more refined LCA on the product.
1) Manufacturing strategies for the DC fan have been dismissed, just its mass is taken into account.
2) The manufacturing process for the screws has been disregarded due to being standardised parts.
3) The HEPA filter’s manufacturing process has been disregarded due to being a standardised filter size – Only the materials have been considered.
4) LED’s are standardised components and therefore manufacturing has been disregarded.
According to a study commissioned by Jacky Brown at Sheilas' Wheels (Telegraph.co.uk, 2017), the average amount of time spent driving is 10 hours. Considering the product is in its planned usage scenario it will be used for this same amount of time as power is drawn from the 12v car outlet socket.
The products primary function is to purify air within the environment of a car. Research has been gathered on the use of the filtration device in order to calculate an estimate of energy required for the purifier over its lifetime using the Eco Audit Tool. It will also be assumed that the product will only be used in this environment due to the limitation of the 12v power supply.
The manufacturer prides a standard 1-year warranty. According to Consumer Watch, a standard air purifier should last between 5-11 years (Consumer Watch, 2017). However, considering the quality, scale and environment of the product and that it comes with a standard 1-year warranty, I will expect that the normal life expectancy of the purifier is 2 years. The manufacturer's website claims that given standard usage in a car environment a filter should last 6 months.
Figure 5 shows the “Material” and “Use” stages demonstrate a comparable example, showing the highest consumptions of energy at 151MJ accounting for 65.25% and 68.3MJ accounting for 29.5% and additionally in regards to CO2: 8.55KG at 62.3% of the 5 stages and 4.26KG at 31% of the 5 stages. Enhancing the "Material" stage will have a significantly more prominent effect on minimising the environmental impact when compared to the other LCA. The product draws is energy consumption from the 12V car socket, because of this the overall reduction on MPG is 0.01, therefore it is a less significant area to focus on.
Figure 6 demonstrates the CO2 emissions of every part, however, the main interest is those that have the greatest effect on the environment which will ultimately lead to redesign. The largest consumer of energy is the circuit board at 40% (60MJ) formed from single crystalline silicon. It is also evident that the LED’s consume a combined total of 28.2% (21MJ). The 3 main ABS enclosures have a total of 22.4%; 33.8MJ. This data will help me to improve the design to ultimately decrease the environmental impact. Fig 3 Shows the material breakdown for the HEPA filter.
The purifier was disassembled into individual components shown in Figure 1 and was made up of permanent/semi-permanent fixings meaning after the disassembly process it was impossible to put back to together. The outer shell (a/b) used a combination of snap and screw fixings these pieces acted as the main structure that the interior parts fixated to such as the Inner Enclosure (3). The motor module (7) fan was impossible to separate from the motor axle with the tools at hand; they could be separated with professional equipment. Additional equipment during disassembly would increase overall energy consumption to complete the process. Disassembly took a total of 8 minutes 32 seconds.
The separation of the fan from the motor axle would require specialist machinery which would use more energy and therefore a more viable option would be landfill. One of the greatest variables that the Eco Audit Tool doesn't take into account is environmental effects. This incorporates the utilisation of electronics which, if put into landfill will discharge harmful materials into the ground – which eventually could drain into water sources.
An additional issue with the LCA Audit Tool is that it doesn’t take into account the life cycles of other essential components. The HEPA filter has a lifespan of 6 months whilst the product has a lifespan of 2 years. Therefore, a total of 4 filters is required to keep the product functional.
A selection of complex parts require complex machinery to carry out complex operations, by optimising parts, in turn, will optimise the manufacturing process reducing energy consumption – improving the “Material” and “Manufacturing” stages.
Another important phase that allows for reduced consumed energy whilst disassembling the product. By designing for disassembly it in turn improved material usage and amount of components.
Improving energy efficiency within the product will improve the “Usage”. This could be carried out through the selection of more efficient components.
This strategy is of the highest importance as it entails the highest impact on reducing energy during the “Use” and “Material” stages.
1) Combining 3 components into 2: The two outer shells (a/b) and the inner enclosure are all made from ABS. Combining these three components into two will reduce the amount of ABS required. Sections of the inner enclosure that is used to secure the fan will be incorporated into the outer shells. As well as reducing materials usage, it will improve the ease of product disassembly.
A) By combining parts an approximate weight reduction of 23% could be achieved. Combined weight of the three parts= 352, reduction of 80 grammes. Fig 8 = Example reduction.
B) A reduction is disassembly time means a quicker recycling process.
A) May increase the complexity of the injection moulding.
B) The additional cost to modify the existing injection mould plates.
2) Part Thickness Reduction: In order to reduce material input a number of components can be reduced in thickness. The outer shells (a/b) have a wall thickness of 3mm. This could be reduced to 1.5mm a reduction of 50%.
A) Reduced the overall amount of ABS used in the product, thus reducing energy levels. Fig 9 = Example reduction.
A) The possibility of reducing the product lifespan.
B) Durability could become reduced leading to it being more likely to break.
3) Circuit Board Reduction: The circuit board uses a significant amount of energy (60MJ) and accounts for 40% overall, after analysing the board it is possible that a reduction of 50% could take place, components could become more closely positioned.
A) By reducing the amount of crystalline silicon it will significantly reduce the amount of energy.
4) Simplifying the complexity of the parts: 53.6% of the overall manufacturing process is shared by the two outer shells (a/b). They both have complex features internally in order to keep the overall structure integral. There are also spacers that separate the inner enclosure from the shell, these can be removed if the shells are reduced to match the size of the inner enclosure – reducing ABS usage and machine energy/time.
A) By reducing internal structures it would reduce complexity; reducing machine energy and time.
B) By removing the internal spacers and reducing the overall size of the shell to match the inner enclosure it would further reduce ABS usage and part size.
A) By reducing internal structure it could reduce the rigidity of the product reducing product lifespan.
5) Removal of electrical component: There are multiple LED’s within the product, one of which is UV required to cleanse the air. A power LED is also used which is not functionally required as the glow from the UV led is more than enough to learn that the device is powered.
A) By removing an electrical component energy consumption is reduced, however not by a large degree.
B) LED removal would decrease energy consumption as it accounts for 14.1%, the second largest of all the components
A) It may not be as obvious to the user that the product is turned on, causing confusion.
6) Reducing the power of the motor: The motor attached to the fan is rated at 12V 0.16A. There are many other motor fan components that are able to achieve the same level of m3/h at a reduced amount of amps. An example is the ADDA AD0824MS-A76GL that is able to achieve 0.10A, a reduction of .06A.
A) By reducing the amount of energy required by the motor it will reduce the overall energy in the use phase.
A) More efficient components could result in a more expensive end product putting it into a high price bracket.
7) Auto Mode: In order to improve overall energy efficiency, a particle sensor could be incorporated into the design to automatically detect levels of pollution.
A) By reducing the use of the motor, it would, in turn, reduce the overall energy consumption of the product.
A) By incorporating additional components, the overall price of the product will increase.
B) By adding an extra complexity there is more room for failure of components.
This product combines the ideas of 1, 3, 4, and 5. The inner enclosure has been removed and instead its features have been incorporated into the outer shell. The outer shell has been simplified internally, and instead, the features taken from the inner enclosure have been used to keep the product structurally integral. The circuit board has been reduced by 50%, as a large amount of the board was excess and not being used. Furthermore, one of the external LED's have been removed, instead, the user can identify that the product is functioning the illumination of the internal LED which peers through the gaps. Further, it would be viable for the product to be incorporated into a service system where filters are replenished and recycled.
The redesigned product presents a total improvement of 23% less energy consumption over the 5 stages, furthermore, a total reduction of 25% has been achieved on the CO2 footprint. The stage with the largest improvement in regards to the air purifier is the material phase. The "Material" stage has seen a decrease from 163MJ (63.9%) to 109MJ (53.2), a total reduction of 53MJ (32%). This has had an effect on the "Manufacture" stage with a slight reduction of 10.1MJ to 9.65MJ. Additionally regarding the HEPA filter, by incorporating an in-house replenishment service of the filters it means they can be processed more efficiently - the EOL has greatly increased specifically for the Activated Carbon as it can be re-manufactured. The LCA results conclude that the design alternation has successfully reduced the economic impact of the air purifier.