Let the surface area of the big house be \( S \). According to the information provided, the surface area of the small house is \( \frac{1}{2} S \) (since it is half the size of the big house).
To find out how much smaller the surface area of the small house is compared to that of the big house, we subtract the surface area of the small house from that of the big house:
\[ S - \frac{1}{2} S = \frac{1}{2} S \]
Thus, the surface area of the small house will be \( \frac{1}{2} \) the size of the big house.
In conclusion, the surface area of the small house will be \(\frac{1}{2}\) the size of the big house.