Table 10. TRIZEE design tools

No	Concept & part element	Eco-efficiency element	Description	Triz principle	Description	Technical response
1.	Dual-function	Reduce material	Efficient use of resources	#22 Blessing in disguise	Reducing material use	Natural wood material
		Extend function and lifespan	Adding chair functions	#5 Merging	Combining one product into two functions	Product innovation
		Extend function and lifespan	Adding chair functions	#6 Universality	Making products with multiple functions	Precise and efficient design
2.	Unity	Increase recycling	Combining wood waste to complete components	#22 Blessing in disguise	Optimizing resource use by utilizing wood waste	Natural wood material, precise design
2.	Unity	Integrate life cycle principles	Considering material and waste sustainability	#22 Blessing in disguise	Optimizing resource use by utilizing wood waste	Natural wood material, precise design
3.	Seat Size	Extend product durability	Designing according to human body size	#9 Preliminary anti-action	Preventing unwanted issues, such as breakage	Ergonomic dimensions
4.	Removal of footrest and addition of backrest	Reduce material	Using resources minimally	#2 Taking out	Removing unnecessary parts and selecting needed parts	Precise and efficient design, connection construction

TRIZEE: theory of solving problems inventively, eco-efficiency.