It's pseudoscience but its method isn't scientifically based. I guess you're believing that it's science-based because of the calculation. But if you'll analyze the whole thing and also research what it means, you'll find that it's just all about superstitions. As being applied to lives and how to get luck, then it's also applicable to gambling and you'll see gamblers believing on it will say that they've been lucky because they've followed a certain suggestion from feng shui like putting some vase on the north side of the house, etc.
It's not scientific but it includes things that are complicated to explain, especially for people who don't understand superstition, Fengshui, and others. Maybe it's superstition but there are still people who will believe it and use it. I only know that Fengshui is about the position of how we should arrange the layout or position that can give positive energy to be in harmony and can also give positive energy to our lives.
There's no scientific basis for it but if you're going to look at the perspective of others, they believe that there's also a relation to science. Well, that's what they're believing.
But to me, it's not really related to science and all about the belief that has been passed on from generation to generation and until now, it's still keeps on living.