I'm no expert in building, but surely a purpose built house would be more logical both practically and financially. Given the success of this season, sponsors shouldn't be too hard to source. I understand the original house was renovated each season, but pulling this one apart and putting it back together, especially if they were looking at doing 2 seasons in one year (unless back to back) just seems very costly. Plus having a purpose built house means DW can cater to fans during the off-season with tours and private functions.
I've said this before, but utilising the Exhibition Centre solely for the live shows would make more sense, too. Much easier building and removing a small set for the live shows than an entire house.
But like I said, I'm no expert in building