During that warm up event, we have received tons of comments and suggestions given by authorities and experts. One suggested that we should add a feature which allows residents to recycle rubbish, since environmental protection is something worth doing. There was also another professional commented on our design, saying that it may not be applicable to older buildings, as our current design requires extra space for the board to cycle back to their original spot. However, the refuse chute of the older building isn’t that big, so it may not be possible to add a track behind the refuse chute. We have two choices, we could either just give up on older buildings and only focus on changing the refuse chute of rebuilt buildings, Or we could think of another design for older buildings which can be fit inside the current refuse chute, while maintaining our original design for rebuilt buildings.

　　Just as we were about to give up on changing the refuse chute of older buildings, we suddenly had an idea, we could modify our design, instead of making the board go up using another track, we could make the board so it go up and down using the same track, and the board can stack up at the very bottom when the board is going down. This can reduce the space needed by removing the extra space for building the second track for boards to go up.

　　Although this design can greatly reduce the horizontal space occupied, in order for the boards to have space to stack up, we have to dig down to provide space, which will increase the vertical space occupied. Digging down (increase space vertically) is probably easier to do than destroying the wall and adding a second track (increase space horizontally), but we do need to keep in mind the reinforcements under the building.