In the field of building energy management, "recommissioning" is a bit of a hot topic. In some cases, it's also a bit of a misnomer, as it's hard for a building to get "recommissioned" when it was never "commissioned" in the first place.

In today's parlance, "commissioning" a building means going through, post-construction, and verifying that the various mechanical systems and features are working as they were originally designed and engineered. See, building systems are engineered based on certain estimated loads -- how much heat, or cooling, or light will a particular space require given local climatic condiions -- and based on published capacity specifications -- how much heat, cooling or light is a particular unit, operating in a particular configuration, supposed to put out.

Of course, all these engineering calculations are based on paper plans. The last time I built a house, each page of the blueprints had a notation that said something like "all dimensions to be verified in the field". That is, what happens in real construction and what happens on paper probably won't be identical.

The same thing's true for mechanical systems. Move a pump a foot from where it was planned to be (even if for perfectly good reason), and now a pipe which was supposed to be straight has a significant jog in it. Change materials to something with less thermal mass, and the heating system can suddenly become undersized. Widen a staircase to meet new code requirements, and ventilation can get thrown off.

So what a "commissioning" step does is go through and test/verify that the systems are working correctly. When they're not (which is hardly uncommon), fix them. Cause the building to perform, from an energy management standpoint, the way it was designed to.

Recommissioning, by comparison, is going through a building which has been in operation for a number of years, and bringing it back "into spec". Whether or not it performed on its first day of duty as it was originally intended to, take steps to fix whatever problems now exist. And problems will, in fact, exist.

Interior space will have been reconfigured, so the ventilation won't work the way it was intended. Other buildings will have been erected nearby, so lighting needs will have changed. Plumbing changes will have been made, so pipe configurations will be suboptimal. And pipe insulation will have been removed (and only sometimes replaced), so that heat is being lost.

Buildings may not move (at least, we hope not), but they constantly change. Tangential parts disappear from radiators, or get added to cover up that ugly cast iron. Windows get cracked, causing drafts which, somehow, duct tape doesn't fix. Doors leak air. Roofs leak heat. Sometimes, both of them leak water.

Going through a building which has undergone twenty years of even the most conscientious maintenance is an illuminating experience (and that's only sometimes a pun). Go through a building which has had indifferent maintenance (like, maybe it's owned by a University with recurrent budget pressures?), and there's a lot that needs doing.

Recomissioning isn't particularly cheap. But it usually pays for itself in 1 - 3 years, based on simple energy savings calculations. Think of it as "deferred maintenance" in the most positive possible sense. Really, it's just intelligent building operation -- the buildling, itself, doesn't have to be intelligent, but the operator clearly does.

Will recommissioning get Greenback or any other campus to carbon neutrality? Of course not. Recommissioning isn't specifically for purposes of achieving sustainability. Of course, it does move us -- or our campuses -- a step in that general direction.