CARY+ Environmentally Sensative Redesign

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CARY+ is a small in-car air purifier pupular across parts of Asia. The manufacturer failed to provide all of the CAD assembly files. Therefore, it was necessary to reverse engineer sections that were missing before re-designing to reduce its environmental impact. An LCA (life cycle analysis) was carried out using an eco audit tool.


System Boundaries

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.

Usage per week

According to a study commissioned by Jacky Brown at Sheilas' Wheels (, 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.

Usage Phase

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.

Life expectancy

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.

LCA Results

Interpreting the Results

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.

The Material Stage

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.

HEPA Results

Purifier Results

Qualitative Analysis

Ease of Disassembly

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.

Recycling & Use

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.

Design Strategies

Optimised Manufacturing

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.

Design for Disassembly

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.

Product Life Optimisation

Improving energy efficiency within the product will improve the “Usage”. This could be carried out through the selection of more efficient components.

Resource Minimisation

This strategy is of the highest importance as it entails the highest impact on reducing energy during the “Use” and “Material” stages.


Minimising Material Input

Minimising Energy Consumption During Production

Minimising Energy Consumption During Use

Final Design

Re-design LCA results

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.

Air Purifier

HEPA Filter