Smart home retrofits: what an existing building can learn – and what it can't
Most of the buildings that will ever exist are already standing. So the question is rarely "new build or not" but rather: how much intelligence can an existing building take – and at what price? An honest assessment.
First the site survey, then the promises
Before anything is recommended, we look into distribution boards, wall boxes and ceilings: Which cables are in place? Are there empty conduits? How deep are the switch boxes, is there a neutral wire everywhere? One hour of surveying saves months of surprises – and decides which of the three routes fits.
Route 1: The renovation – lay the bus
If renovation is happening anyway, the answer is simple: put the bus cable in. With open walls, the KNX infrastructure costs little more than conventional electrics – and the building stays open to everything for decades, from lighting scenes to energy optimization. Every renovation without empty conduits is a missed opportunity.
Route 2: Wireless – strong, with clear limits
Where nobody wants to chase walls, we work with wireless components: switching actuators in deep wall boxes, batteryless push-buttons, wireless radiator valves. This works well – if you know the limits: range through reinforced concrete, battery changes, and not every wireless solution speaks open standards. We rely on systems that integrate into KNX rather than on app islands.
Route 3: Hybrid – the realistic default
In practice, the mix almost always wins: bus where the floor, ceiling or bathroom happens to be open anyway; wireless where the wall stays closed; central intelligence in the distribution board. This way the existing building grows into a system in stages – each stage worthwhile on its own, all of them together a whole.
Where to start?
The most rewarding entry points are almost always the same: shading (a comfort gain you feel immediately, often already motorized), lighting in the main rooms (scenes instead of banks of switches) and heating (individual room control saves real energy). Door communication and audio follow elegantly once the foundation is in place.
And what is better left alone?
Honesty lasts longest: if you would have to rebuild half the apartment for a single wireless lamp, leave it. If you are renovating in three years anyway, retrofit only what is reversible today. And if you are considering a cloud island solution that nobody will maintain in five years, you are saving at the wrong end. In existing buildings too: first the plan, then the product.