Donations to a capital campaign (e.g. from individuals and businesses) are treated in the same way as grants (e.g. from foundations and governments).
Your funders and donors have provided money that is intended to benefit your organization over the life of the capital purchases. In the same way that the cost of a capital asset is spread over the years of ownership, the benefits of a capital grant must be spread over the same years, using the same technique.
You should discuss your organization’s capital policies with your accountant, to make sure they are appropriate to your particular situation.