Loxone in older buildings: what really went wrong retrofitting a Bavarian villa

The project sounded manageable on paper: a 1960s villa in Anger, around 280 square metres, the owner wanted Loxone for lighting, heating and access control. The electrician had already booked a date. Then they called us — three days before the planned start of installation.

What we found when we opened the distribution panel

The first look into the panel was sobering. In an old building of this generation, "checking the electrical installation" usually means: plan for surprises. In this case we found a mix of 2.5 mm² and 1.5 mm² cables with no recognisable scheme, three generations of fuses, and — the real problem — no continuous neutral conductors in the switch boxes.

For a Loxone system, that is critical. The Loxone Tree bus runs over four wires (two for data, two for power), but it needs a clean basic supply in every switch box. What is taken for granted in a new build is often simply absent in older buildings — because no one needed it back then.

That afternoon we decided to push the planning back by two weeks. The client, an entrepreneur from the Berchtesgaden area, was initially not amused. In hindsight, that decision saved him roughly 4,000 euros in rework costs.

The wiring question: Tree or Air, and why we usually pick Tree

In older buildings the question always arises: wireless or wired? Loxone Air is tempting because you don't have to pull new cables. We use Air in our projects — but rarely as the main system, mostly for retrofits in individual rooms where pulling cable would be disproportionately expensive.

For this project we chose a hybrid solution: Tree as the backbone in areas where we had to pull new cables anyway (heating, main distribution), Air extensions for the upper bedrooms, where a single switch box would have meant twelve metres of hollow-wall drilling.

The result: Miniserver Gen 2 as the central unit, nine Tree extensions for lighting and blinds on the ground floor and first floor, four Air-Tree extensions for the second floor. Total installation time: 14 working days — around 60 percent more than a comparable new-build project of the same size. You have to factor that into the calculation.

What really takes time: programming or cable?

A question that owners often ask us: "How long does the programming take?" The honest answer: in older buildings, programming is rarely the problem. Pulling cable, upgrading the existing installation, testing every single actuator — that's what eats the time.

For this project we needed about three days for the actual Loxone configuration. Eleven for the electrical installation. Heating integration via Modbus to the existing Viessmann unit: half a day, including parameterisation. Integration of four Loxone NFC Code Touch units at the main and side entrances: two hours.

The ratio surprises many people who know Loxone projects from new builds. But it is the reality of the existing-building world — and anyone who doesn't communicate that from the start gets into trouble at billing time.

Three mistakes we made on this project

It would be dishonest to write only about what went well. Three things we should have done differently:

First: we committed to the heating control too early. The Viessmann unit was Modbus-capable, but had a firmware version that used a particular register layout — different from the documentation. Two hours of troubleshooting, a call to Viessmann support, and ultimately a firmware update later, everything ran. Since then we always ask for the exact firmware version of heating systems before pricing the Modbus integration into the offer.

Second: we agreed on the visualisation only after commissioning. The client had different ideas about the room layout in the Loxone app than what we had set up. No big problem, but unnecessary rework. Since then we run a short workshop format before the programming, in which we agree the structure in Loxone Config together.

Third: we created the documentation too late. After 14 days of installation, our own overview is still good — but anyone who works on the system again a year later for an extension is grateful for clean wiring diagrams. That sounds banal, but in everyday project life it slips easily.

What the system delivers today

Twenty months after commissioning, we asked the client for his summary. His answer was matter-of-fact: heating costs had fallen by about 18 percent, which he attributed to the per-room control. The shading system saves him daily manual operation of eleven external blinds. What surprised him most: that he hardly uses the app any more, because the automations simply run.

That is exactly the goal. A well-planned Loxone system should make itself invisible in everyday life — not constantly demand attention.

For questions on planning a Loxone retrofit in your existing building, we are happy to schedule an initial conversation. For an overview of our Loxone projects in the Berchtesgaden and Chiemgau region you will find references in our portfolio.

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