The e-magazine for KNX home & building control

Trade Talk: we must spread the KNX word to M&E consultants

Simon Buddle explains why KNX professionals must evangelise about how simple, reliable and cost-effective KNX can be for multiple system control in apartment blocks.

That’s definitely enough mince pies and terrible films for me. How about you? It felt like a very compact break. Working at 5pm on the 23rd and straight into Christmas Eve the following day. A week later, we’re out the other side, it’s the start of another year, and time for a rant. As a general rule, I don’t like to moan too much in an article, BUT, I just want to know who in the world decided that the right place for an emergency knock off button is right next to the plant room’s light switch. I mean, really! That’s asking for trouble, right?

And talking of asking for trouble, how many control systems does it take to run a block of upmarket apartments? The punchline in this not-so-funny joke, is four. OK, we need to rewind a little bit here, so pull up a chair, and let me tell you a story.

Whose brilliant idea was this?

A happy KNX story

A couple of months ago I was called out to look at a problem with some heating in a very swanky penthouse apartment. The system was a fully-integrated KNX system doing all the usual stuff such as lights, blinds, air-conditioning, heating and a few other bits and pieces. The call out was pretty routine; it turned out that one of the thermoelectric actuators had failed and so one room wasn’t getting any heat from the UFH manifold. Whilst I was there chatting with the facilities manager, he asked me if I could take a look at another apartment that had a similar heating issue, but which didn’t have KNX in it. “Sure, no problem, glad to help”, I said. So off we wander to the next heating issue. And this is where the world of madness and trouble starts to unfold.

Before I go any further with this particular rant, I want to make it totally clear that all of the products I’m about to mention are absolutely not the issue; they are all great products made by reputable manufacturers and installed to a good standard. The issue though, will reveal itself.

A sad non-KNX story

So the unit controlling the heating manifold is a Titan CCM202. There were three 24V outputs opening and closing the vales with two high-current relay outputs to operate the electric floors in the bathrooms. Control system one.

The electric underfloor heating is switched on/off by the Lutron lighting system using some volt-free outputs. Control system two.

The in-room thermostats that control the underfloor heating and fan coils is from a company called Distech Controls. Control system 3.

The Distech Controls BACnet controller for in-room thermostats.

System one and three talk to each other over BACnet. The centralised plant control ‘listens’ to all local apartments’ BACnet communications via a Trend IQ4, one per apartment. Control system four.

The centralised plant control ‘listens’ to all local apartments’ BACnet communications via a Trend IQ4.

And there we have it: four control systems to do a very simple job. OK, I can hear someone at the back muttering about ‘it all being fine as it’s all on BACnet’. But if that were true, I wouldn’t have a story to tell. They are all on BACnet, but programmed by different companies. And guess what? Apart from the Trend maintenance team, no one has a copy of any of the software. But surely you can just scan the network and find all the relevant points, so it’s no big deal, unless… one of the devices has reinvented itself as a toaster and point blank refuses to discuss/obey/take part in any of the other devices, or even acknowledge that it may in fact be a BACnet device or point at all.

The last part to add into this maelstrom of trouble is the absence of any documentation whatsoever. No schematics, no points lists, no O&M documentation of any description. Nor indeed any knowledge of the original installers – except the Trend guys, who, to be fair, are on point, but won’t touch anything in the apartments. Another tiny detail I should mention is that there are 230 of these apartments.

Become an evangelist for unified KNX solutions

So there you have it; rant over, time to calm down a bit. The lessons here are clear, and primarily, there are two. Firstly, the M&E design or controls design should have been considered in more detail. We, as KNX integrators, ought to be showing our wares to as many M&E consultants as possible, demonstrating how simple, reliable and cost-effective KNX is in this type of scenario. I would go so far as to say I don’t know of a system better suited to the job of these four control systems.

We need to let the world know how simple, reliable and cost-effective KNX is for managing control systems in apartment blocks.

Secondly, whoever does the work must provide programs and documentation at the panel in each apartment. The electronic sub systems are, after all, the property of the homeowner and therefore they should be given all of the relevant information to run, service and maintain the systems.


I don’t need to bang the KNX drum here; it’s benefits in this situation are obvious to all of us because we already know KNX. It’s to those that don’t know KNX that we must train our sights on. Spread the word – it’s good for everyone! As my old boss used to say, “If the pie is bigger, everybody gets to eat more.”

Simon Buddle CEng MIET, is a consultant for Future Ready Homes, a specialist in BMS and ELV services system design.

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