In some cases, you can’t rebuild the old building because the building codes have changed since the original construction. The new construction must meet current building codes to be approved for occupancy.
The good news is that modern codes will typically improve the suitability of the building. You will have an easier time finding space to plug in computers and other electronics, and your electrical system will be better able to handle the demand – less dimming of lights and a reduced risk of fire from an overloaded circuit.