Babel Buster Network Gateways: Big Features. Small Price.
Now is the time when we discover whether we have taken the right approaches throughout the process.
The fifth in a series of articles on the delivery of BMCSs to our
The Construction Process
Tendering a BMCS
Specifying Control Systems
Control System Technologies,
and the series introduction BAS or BS?
We have now worked our way through most of the process of obtaining a BMS. We have finished the construction of our building: all devices have been installed, all the wiring is in place, and we are ready to start up our building.
Okay, in reality, many projects have staggered starts. This causes some levels of complexity as often you may only have some parts of the central plant working. In retrofits, often you have to keep the plant working and do organised change outs in evenings and weekends. Often, you move clients from one floor to another as you refinish one floor at a time. We will not try to address projects of this complexity in this article, but we must recognise that this raises issues that increases the difficulty and planning of commissioning (as well as construction) by a whole level of magnitude.
For the purposes of this article we will look at commissioning as a single process, or logical series of processes carried out sequentially on the building as a whole.
Now is the time when we discover whether we have taken the right approaches throughout the process.
To simplify, there are two possibilities: a good project and a baaaaaddddd project.
The project has been done right from the start, in a proactive manner, following the methods recommended in earlier articles. (As opposed to a project that is built reactively, as suggested in the last article; and we shall see shortly, for the first time, the full and ugly consequences.)
Let's look at the properly approached project with the well thought out commissioning procedure as a natural part of the job.
This project will be a piece of cake, assuming we do not have trouble from an external source (poor design, faulty mechanical or electrical equipment, shoddy contracting, bad project management, etc.).
With a well-planned project we will observe the following:
There is a proper programme (project schedule) and said programme allows a reasonable period for balancing and commissioning between the completion of installation and project handover.
Rough-in has been done by skilled electricians who properly label all wiring.
Commissioning sheets confirm every input and output has been end-to-end checked for continuity of wiring.
The controls contractor, the mechanical engineer and the mechanical contractor have had meetings to fully review the intended sequence of operation of the plant and the control panels have been pre-programmed, or the programs have been written and are ready to load into the controllers.
All the terminal devices have been professionally mounted and terminated and are ready for commissioning.
BAS commissioning has been coordinated with the balancing commissioning agent.
The mechanical contractor and the builder have coordinated tests with the fire protection system and other trades whose work affects the operation of the mechanical plant.
The BAS contractor has experienced and trained staff who fully understand this complete project scheduled for commissioning.
The programme has been met, in that the electrical and mechanical system installations finish just as we are ready to commission.
At this point the installation staff or electrical subcontractor who has executed the installation of the wiring formally turns the project over to the commissioning technician. They will use the I/O sheets to review and sign off each and every physical point to confirm that the wiring is correct.
Once every point has been confirmed for continuity, the electrician powers the system. (In a bad installation this is called the "smoke test". If nothing starts to smoke it is generally accepted to be okay.) At the end of this step, we are basically accepting that the installation has been done properly.
But this states nothing about the correctness of the system operation.
The second step is to establish communications between the controllers and across the system. (This may be swapped with the third step that follows depending on the manufacturer's system and the contractor's philosophy.) All controllers on the network are brought on line and it is confirmed that data can be passed between them. The speed and difficulty of this step varies immensely with different systems depending on how "robust" the system and architecture is (see notes on architecture below.)
The third step is to confirm the operation of every point in the controller. All outputs are driven on and off, open and closed, etc. Each input is confirmed for a valid reading and calibrated. This confirms that the all the inputs and outputs work and are numbered correctly. (The author has seen projects where the wrong room sensor is tied to the wrong zone valve or VAV box, and the building meanders along for years before it is detected.)
There are several practical ways that the I/O is verified. A technician may work alone carrying a handheld device, which he plugs into each controller. There may be two technicians. One is in the field, testing the devices, the other is at the BMS MMI (man-machine interface) confirming the operation of the system via two way radio. This is probably the most common way to commission modern systems.
Having one technician working at the MMI while the other is in the field is one reason why system wide communications has to be established prior to verifying operation of the inputs and outputs.
For air and water flow commissioning the BAS should work closely with the balancing and commissioning agent. This is particularly true of VAV projects.
Okay, now we have a working network of controllers and I/O points.
Now we have to take the final technical step, and prove the sequence of operation. This involves reviewing every line of the sequence of operation and confirming that the equipment behaves in the expected manner under each (actual or simulated) change in conditions. We now have a completely working system.
In reality, this often requires working with air and water balancing technician to confirm proper water and airflow readings and to confirm that the entire system works as a single unit.
The final step is to demonstrate the installation to the engineering authority, and often the contractor for whom the BMS contractor is working. At this point formal sign of the project is given and the project moves into defects liability (warranty). On larger and more formal projects this will involve running the system for a period of days (usually one week) without disruption and to have trend logs to confirm continuous operation.
At this time the clients will be given the first round of training on the operation of the their particular building. (On larger, well-organised projects, the client may have gone for earlier training to understand the operation of the BMS technology itself, not as to how it is applied to their project.)
Substantial Completion is granted for the project and the kindly project manager for the mechanical contractor signs off the project and sends the cheque for the remainder of the project to the BMS contractor, and everybody is happy.
Okay, that was too easy, and hence, for the purposes of article reading… boring. For excitement, let's look at the…
First, we recognise from our previous article on construction, that one or all of a series of compromises have already been made.
Poor equipment selection
Shoddy installation practices
Insufficient time for proper commissioning
Poor coordination of the trades, and hence, target dates for completion of various steps have failed to be met.
No-one fully understands the intent of the complete project.
Cost savings result in a "stressed" architecture, that will work in theory, but in practice will barely stand up.
Okay, let's start the commissioning process. We recognise that being a "bad project", the commissioning is started on Friday morning before turnover to the client the following Monday morning. Everyone had planned on having two weeks to a month to commission the project, but the other trades all ran late getting their work done, but we can't move the client's occupancy date. So we have one day to commission the system. The consultant has been called in to witness the system and to sign it over.
This is all done on the vague hope that the controls contractor is going to be given power, flick the switch, and magically the whole system is going to operate flawlessly.
Haahhhh. Not a chance.
First problem. Several pieces of equipment are lying open with wiring spread out waiting for the electrician to complete the power wiring. Some thermostats haven't been mounted, waiting for the painter to paint the walls first.
In this sort of project, compromises are made, leaving some equipment out of the commissioning process as "minor defects" to get the project to substantial completion.
There has been no formal test of the wiring prior to power. Everybody hopes (or prays fervently, in the case of those truly religious individuals on the crew) that all the wiring was correct.
Fuses blow and smoke comes out of a variety of pieces of equipment. Hence the term "smoke test". Now we have additional systems that can't be checked, as we have to wait for new controllers and random devices to picked up or shipped in from overseas. More minor defects to be corrected later.
The contractor connects his laptop to the system and hopes to be able to immediately demonstrate the sequence of operation. No need or time for that silly calibration step.
Unfortunately, this is that "bad project". Remember? The contractor is unable to even see the majority of the controllers on the network. This may be caused by:
Poor installation of electrical equipment by others, such as the variable speed drives (an absolute guarantee that network communications are going to fail) which creates noise in the data communications network.
Stressed Architecture as related before. (See following paragraph).
Network wiring faults. Improper grounding. Poor connections.
Inexperienced technicians who have little idea how to troubleshoot network problems.
Stressed architecture deserves special mention. This is very hard for outside parties to evaluate. The controls contractor has had to make concessions in the design of the system to meet budget realities. The system has been "stressed" by selecting controllers that barely meet the broad specification, with no thought as to whether they are actually adequate for the specific project. This is exacerbated by expecting one hundred zone controllers to communicate on each sub-network. This keeps down the number of very expensive primary controllers. In theory, this system may work. In reality, even if we can get communications working, this network is closely analogous to a house made of cards. Even minor changes are almost impossible, and it takes only a very small shove, to cause the whole system to collapse. When it collapses, the whole painful process of putting up our house of cards is redone. We do not fix the basic design flaws.
This puts incredible stress on the commissioning technician. The technician has a crowd of contractors, balancing agents, and consultants hanging over his shoulder, while he is desperately trying to even get the system back up and communicating.
This is the point on this sort of project where the consultant should pull the pin. Forget false hopes of pulling the project off at the last second. It is time to advise the client that the project will not be ready for handover as scheduled.
Unfortunately, this brings another retribution - liquidated damages. On what may be the majority of projects, every subcontractor blindly states that he will meet the project schedule, even if the subbie knows that there is not a chance of meeting the projected completion date. The first subbie who admits that they can't meet the schedule is tagged with being responsible for holding up the project, and may be liable for liquidated damages.
Most contract documents have liquidated damages, which are penalties for not meeting the project schedule. These can range from a few hundred dollars a day to tens of thousands of dollars per week. No one wants to take the blame for delaying the project, so the project goes blindly ahead and we have the situation mentioned at the start of this section on the "bad project"…A compressed time frame to commission project that is barely even physically completed.
to our jobsite.
Assuming we have gotten this far, and in reality, on a rough job, this is well after the expected completion date, and everybody is blaming everybody else and putting incredible pressure on the controls contractor to "get the damned thing finished".
For the above reasons, it is very often the case, that there is a rush to get the project signed off. It is the opinion of the author that the majority of projects are granted substantial completion without adequate commissioning of the BMS.
As stated in our first article, Steve Hennessey of AHA Management, did a survey of buildings in downtown Sydney and discovered that, on average, buildings with a BMS performed worse than buildings with old electric or pneumatic controls.
The lack of commissioning is compounded by other faults that go hand in hand with a rushed and badly managed project. Compound this with inadequate design and supervision by the consulting engineer, (who is in exactly the same boat as the contractors - shrinking fees for doing the same work) and you have a project with a dissatisfied client.
When things go wrong with the mechanical services, you can be sure the first person everyone is going to blame is the controls contractor. External problems such as poor electrical wiring, (in particular Variable Speed Drives) and weak mechanical design and installation will automatically be blamed on the control system. Often problems are the fault of the building automation contractor. Just as often, they are not.
Next month we will finish this series of articles by looking at the long-term operation of the building.
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