The short answer is that we can’t know the operating costs of a building that we haven’t designed yet. However, we can specify some parameters which would help to narrow the possible answers to the question:
The Town already pays the operating costs of a set of buildings that house the Council on Aging & Human Services (COA&HS) and the Parks & Recreation Department (PRD), specifically Bemis Hall and two of the Hartwell Pods. So the appropriate question is not what the operating costs of the Community Center will be, but how those costs will be different from the current costs.
The Town will continue to pay operating costs for Bemis even if the COA&HS, moves out (though it is likely that those costs will diminish as the intensity of use diminishes, and the Town’s expenses are likely to be increasingly offset by rental income and fees from community organizations). But most plans have at least two of the Hartwell Pods disappearing — demolished or integrated — with the construction of the Community Center, so the appropriate focus here is on the net change in operating costs for the Hartwell Pods versus the Community Center.
The Hartwell Pods are very inefficient buildings, while the Community Center would be a very efficient – probably net-zero – building, so there would be a large savings in utility costs. That savings might be offset by an increase in custodial costs. The Pods currently have part-time custodial support (carried on the school budget), while the Community Center would probably have a full-time custodian. (Additional personnel expenses, such as staffing for a reception desk, are very hard to model at this point, because we don’t know if those tasks will be necessary, or if they might be performed by volunteers or rotating staff or seniors working for tax abatements.) For planning purposes, it is reasonable to expect that any net change in operating expenses from a new Community Center – a decrease in utility costs offset by a possible increase in custodial costs — would not have a discernible impact on property tax bills.