# Assessing Energy Efficiency in Desktop-Size FFF 3D Printers
## 3 Results and Discussion
To validate the regression model, diagnostic checks, including residual plots and standardized residuals, were performed to ensure the assumptions of normality and homoscedasticity were met. Additionally, descriptive statistics such as mean, standard deviation, and confidence intervals were calculated for each energy metric to provide a comprehensive overview of the dataset. By leveraging the robust statistical tools available in Minitab, the analysis ensured accuracy and reproducibility, strengthening the confidence in the significance of the observed relationships and the study's conclusions. A natural assumption is that smaller products should be printed on smaller machines. While generally accurate, this is not universally true: a machine with over twice the working volume achieved a slightly better energy efficiency than the smallest machine. Regression analysis indicated a statistically significant relationship (\(p\) = 0.005) between machine volume and energy consumption, showing a 0.00001883 kWh increase per 1 cm3 increase in working volume. Machines with closed chambers consumed slightly more energy (0.0281 kWh) than open-chamber machines, though this difference is not statistically significant (\(p\) = 0.258). Similarly, while direct-drive extruders showed better energy efficiency by 0.0155 kWh, a \(p\)-value of 0.522 suggests that extruder drive type is not statistically significant for FFF energy consumption. Figure 3: Comparison of energy consumption per gram and per minute for FFF 3D printers. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Device** & **Energy Consumption** & **Percentage of** & **Energy Consumption** & **Percentage of** & **Weight of** & **Energy Consumption** & **Percentage of** \\  & **per Machine Prating** & **Minimum Energy** & **per Test Point** & **Minimum Energy** & **per Test Point** & **Minimum Energy** \\  & **Volume [BW/Wm\({}^{2}\)]** & **Consumption [\%]** & **Volume [BW/Wm\({}^{2}\)]** & **Consumption [\%]** & **Test Point [\%]** & **Weight [BW/Wg\({}^{2}\)]** & **Consumption [\%]** \\ \hline _Anet ASM_ & 0.000000503 & 205.2075 & 0.00719 & 100.0075 & 5.04525 & 0.011149 & 109.54\% \\ Corality ECHO PRO & 0.000000043 & 132.0273 & 0.04849 & 20.5675 & 4.62575 & 0.02339 & 249.57\% \\ Creilly Endar J3 V1 & 351.4173 & 0.01199 & 166.8775 & 4.64725 & 0.03373 & 198.28\% \\ Creilly Endar J3 V2 & 0.000007521 & 305.1573 & 0.01016 & 164.2785 & 4.57925 & 0.018972 & 195.24\% \\ Creilly Endar J3 V3 & 0.000007789 & 317.0079 & 0.01203 & 167.265 & 5.57925 & 0.016346 & 160.78\% \\ FlashFlow Center Pro & 0.000001807 & 480.6476 & 0.00571 & 105.7878 & 5.84675 & 0.0101738 & 100.00\% \\ Puss 3 MK3 & 0.000001515 & 30.8578 & 0.01048 & 145.3375 & 5.88025 & 0.014650 & 143.73\% \\ Rausel Dv2 & 0.000003732 &  
After producing the test elements, each was weighed, and energy consumption was calculated per unit mass. This significantly altered machine rankings, with the Zortrax M200+--the machine with the longest production time--showing the highest energy efficiency. Although a mandatory raft was included for this machine, considered as technological waste, the energy efficiency calculated with raft mass was 0.006 kWh/g, nearly double the efficiency of the next best machine. Examining average mass values per machine revealed a 40% mass difference between the lightest and heaviest samples. These variations underscore the challenge of comparing results across different FFF machines in terms of energy efficiency and product mass consistency, even with tightly controlled parameters. An additional point of interest is the performance of the Ender 3 devices. Versions V1 and V2, operating on the same NC code, showed no significant efficiency differences. While the code for V3 was generated by a different engine to match production time, energy consumption remained comparable to the earlier versions. However, adjusting V3's speed settings to its true PLA processing capabilities improved energy efficiency, yielding a total consumption of 0.0635 kWh--substantially lower than that of V1.