The function that models the value of the building is given by:
\[ y = 240,000 - 20,000x \]
To find the y-intercept of this linear function, we need to determine the value of \(y\) when \(x = 0\). This represents the initial value of the building at the start of the depreciation period.
Substituting \(x = 0\) into the equation:
\[ y = 240,000 - 20,000(0) \] \[ y = 240,000 \]
Thus, the y-intercept is \(240,000\). This means that when the building is new (at year 0), its value is $240,000.