Balancing energy performance with functional outcomes during commissioning and system operation.

I firmly believe that improving the energy efficiency of our refrigeration and air-conditioning systems is the major technical challenge of the next 10 years. When I look where we need to be in terms of fuel consumption, operational effectiveness, and system availability by, say, 2050, it is clear that massive change is imperative. However, I have no idea how we will achieve it. To make matters worse, I have felt this way for most of my career, but I haven’t seen any indication that the necessary step change is in preparation.

This dilemma can be summed up in the balance between efficiency (how expensive it is to operate a system) and efficacy (how well it works). This strikes at the heart of the commissioning process; the client requires his stuff to be cold and won’t be happy unless it is. The supplier is under huge time pressure to get the process on-line, and given the choice between being cold or being efficient but not cold enough, there is never any real debate. Efficacy wins every time.

Usually this sort of works; achieving operating temperature is easily measurable and clearly demonstrable—it is just the sort of SMART objective that contract lawyers love to base their documents on. However, when time pressure is on, and particularly when things are not running particularly smoothly, lots of ways exist to achieve temperature compliance by sacrificing other desirable features. Energy efficiency is usually the first casualty when deadlines loom.

Proper commissioning comprises three nested layers, and like a classic arcade game, you can only proceed to the next level by achieving a certain level of proficiency in the current one. Level One is “setting to work”—making it go round and round and up and down, and getting the stuff down to temperature. Once this is happening, it is possible to advance to Level Two, “tuning up.” This is where efficiency is won or lost: making the system operate as the designer intended and ensuring that the temperature is not being achieved at the expense of other desired or intended effects. Of course to do this, the guy doing the commissioning needs to have a clear idea of what the designer intended in the first place.

Some iteration will follow, since the designer may not have been able to foresee all the circumstances that arise on site. If the commissioning guy guesses what the design guy wanted in response to these unknowns, his efforts at Level Two are as likely to move him away from the goal as toward it.

This is when successful commissioning moves to Level Three, “closing the loop.” Only when the response of the system to the real world has been fed back to the designer and has been confirmed as acceptable that the whole job is complete.

It is therefore quite striking how few installation contracts include a mechanism for feeding performance information back to the designer as part of the handover process, and even fewer include the equipment or system designer in periodic reappraisals of system performance throughout its life.

Fortunately, we seem to have all the tools necessary for whole-life performance analysis available to us. The missing ingredient seems to be the will to do anything with them. I can’t understand why this should be; suggestions are welcome.

Efficiency: the state or quality of being efficient

Efficacy: the ability to produce a desired or intended result