Old house renovation HA firendly: thinking ahead

Hi everyone,
I am a long time user of HA but I have mostly used “smart” devices like IKEA lamps or plugs or more generally, off the shelf products. This was mainly because I have always rented a place and could not do major electrical changes (I’ve still managed to install my Netatmo thermostat everywhere :smiley: ) .

Now I am about to completely renovate an old house and I believe I am in the perfect position to “think ahead” and make sure what I will purchase will not blow in my face when I will try to connect to Home Assistant.

So, thinking HA first!

I would need some advices on what kind of electrical ecosystem system to install.
My goal would be to “unlink” all endpoints, lights, switches, possibly sockets) from a direct connection with each other, but rather have each light operated by a centralised relais, commanded by the switches.

This would allow me to program centrally the behaviour of the system, i.e. having one switch turning all the lights off when I exit.

Since I am about to renovate everything, drawing the necessary cables will not be a problem.
I would definitely base it on cables and not on anything wireless: at least the fixed things like sockets, switches lights, need to have a high level of predictiveness for an average user (a guest, older people, people unfamiliar with automations).

Can you advice if there is a solution that offer similar functionalities?
I live in Belgium so I looked first at the Legrand products, but I am not really able to understand the underlying physical architecture.

Is anyone else employing this route?

A couple of other considerations:

  • ideally it should be local only, cloud + local would be good but in 10 years I’d like to be able to control these things even if the mother company dies
  • I will also use other smart lights like ikea or philips but for other purposes like light temperature, other kind of sensors etc.

One option you might want to explore is KNX, which is a popular standard for home automation. It allows for centralized control of various devices and is widely supported by different manufacturers. In terms of local-only control and future-proofing, you can consider combining HA with a local hub or controller.

That kind of rules like every vendor firm/software and leaves you with self-brewn *ware like esphome

This way you can buy hardware independtly from the manufacture as long you have supported chips like esp’s or pico

Easy to do with a battery load of relais and some/one esp’s. They can be programmed so that they work independently from HA.

You can also buy (expensive) ready made I/O boards like this :point_down:

Don’t think HA first, think smart home and future proof first. Renovating a house is a long term commitment. What you add in the walls now will shape what you can do or can’t do for decades to come. You don’t know if you will still be using HA in 10 years or if HA will still exist in 20 years. Your cables will still be in the walls though. A good setup will make HA work great, but it will go beyond that.

Try to keep it to well established standards as much as possible. Cat / Ethernet cabling is a good starting point, even for things outside of the smart home world. KNX is very well established open industry standard that fits cable based smart home solutions perfectly and is as future proof as you can possibly get:

KNX is an approved standard by the following organisations, (inter alia):[1]

  • International standard (ISO/IEC 14543-3)
  • European standard (CENELEC EN 50090 and CEN EN 13321–1)
  • US standard (ANSI/ASHRAE 135)
  • China Guobiao (GB/T 20965)

It’s not inexpensive though.

If wireless is an option, Zigbee or Zwave are good choices. While adoption rates may change and vendors / protocols come and go, all these are entirely local and well documented standards. Open source drivers exist for both, so you can keep an existing network running as long as the hardware works.

About DIY. While possible, I would avoid basing your entire hardwired house setup on a full DIY solution. It’s as proprietary as it can get (proprietary to you) and noone else will be able or willing to maintain / extend it. This can be a real issue for resale value of your home, because the new owner would have to pay someone to rip all your DIY stuff out of the walls and replace it.


Quality @HeyImAlex reply :joy:

It’s simply not possible to own if you don’t have control/ownership over hardware AND software. Buying something today from a manufacturer and just HOPE they will continue support it over 10 years including fixing bugs and adding new features is just a WISH. :pray: (check all the blog posts on the HA site of vendors abandoning the hardware they sold… :put_litter_in_its_place:)

On the other hand if you own hardware which allows you to run your own firmware on you are not depended of the manufacture (which typically let you down sooner than later :fallen_leaf:)

It’s simply about having a black box at home and hoping the vendor will continue supporting it or having a device you can call your own including modifying it, adding new features, etc. :gift:

It’s essentially about the right to repair/own :star2:

@nick2k3 plans to have all endpoints centralized so to the contrary what you say: nothing easier than change/ do whatever with the hardware :man_shrugging:

I expect that it should be easy feasible to “preper” for a central (premium) solution like KNX were all wiring comes together in central cabinets but than just spend a fraction and install some relay/inputs solution with esphome. At whatever later point in life and for whatever reason another solution can be a drop-in replacement or the house can be advertised as “KNX ready” when sold :sunglasses:

As it was mentioned a few times already, go with KNX for all cable things. :slight_smile:

And there are news about KNX and HA, just came in last week:

I agree that KNX is a good solution when wired is a must.
It’s just quite expensive and the DIY/cheap idea gets another meaning.

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If it would be me, I wouldn’t bother on planning this to the end. Too many variables that could come in between during the renovation.

What I’d do is putting empty tubes everywhere, so I can always pull some cables through it, if needed. If not needed, they can stay where they are, they are not expensive at all, and you have every possibilty to do whatever you want later.

In an essence: don’t put cables or whatnot everywhere, just make it for a very easy installation afterwards. Renovating is expensive enough, no need to blow out your budget at the beginning, for things you might need (or not).

KNX requires very specific cabling (types and topology). While imho this is very easy to install at build time, it is not a well fitted system for after-thought quick renovation.

Also KNX is known to be quite expensive, but imho most comparisons are apples vs pears :apple::pear:. Since you generally plan a Knx installation very detailed, it often ends up at the beginning with a lot more features than a “do some things now and extend later” build.
A typical 230V/16A switch channel on a ~16-fold actuator costs <20€ (without energy metering capabilities).

You could also have a look into DALI for lighting. This is also a good match with KNX for controlling it.

And Modbus for energy monitoring etc.

So when @nick2k3 does like he planned initial and have all lights, switches, etc. together in centralized cabinets he can’t make use of KNX anymore even though every endpoint is available? Obviously a simple wall switch doesn’t need to be connected via 1.5mm² solid copper wire just for signaling but it still works with low DC voltage instead of 240VAC. :zap:

Indeed - people build houses for less than other people pay for they knx installation. :joy:

A little less DIY but probably still completely ownable (future proof :muscle:) are the sonoff DIN Powermeter/relay series.

Still “missing” the input as far as I can see and while already relatively cheap it can be still made for much less when doing the hardware part a little more DIY by combining simple relay boards like these :point_down:

or even ditch the 16A relays and go straight with the beefier DIN-mountable 30A ones… :muscle:

paired with a esp/pipico and some more inputs added - probably via optocopulers :bulb:

Going a DIY router like this I expect to be somewhere around $1 per endpoint/relay - just for example a ready made 8-relay board with a esp8266 is sold for less than $10 :money_with_wings:

But instead of choosing a wifi only solution I rather would go with a esp32 with ethernet to have everything neatly wired :electric_plug:

Technically it is possible, but you wouldn’t do it that way from the beginning. In KNX you would span a tree topology (with a YCYM 2x2x0.8 EIB certified cable) (or open ring) to every sensor point (presence detector, switch, thermostat etc). This saves a lot of wiring work and materials compared to a 100% star topology.

Keep in mind to talk to your (/a) certified electrician about your plans. Depending on your local legislation you may need a certified test protocol of your whole electrical installation.

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Now I remembered this rocketcontroller (formerly robotdyn) devices which also feature inputs and does have various versions (solid state relays, mechanical relays, AC/DC, …) :point_down:

They are quite affordable ($20 for 4 AC relays with 4AC Inputs, DIN housing and PSU for example) and also have expansion modules (4 relays/4 Inputs, DIN hosing, PSU sells for $15)

Nice touch is that these device come already “freed” so no sh!tty vendor firmware but tasmota for the start (which should allow easy OTA to esphome etc.) :rocket:

As a side note: The website also lists KNX as a “internal module” for this controllers - but it looks like they are not available (yet?) in the store.

Oddly enough the website isn’t available behind a piHole :person_shrugging:
Tasmota has KNXnet/IP (“Routing”) support since a long time, so this may be the reason. From what I’ve read (never tried Tasmota myself) it’s a quite basic implementation (few DPT, no Secure, no ETS configuration).

Hi everyone, thank you for all your extremely useful inputs!
I have read and re-read the topic and in the meantime gathered more info on KNX.
Searching for electrician to whom to ask for a quotation for the whole works (not just domotics but the whole revamping of the electrical system + solar etc…) I see that many in this area support KNX.
I think it’s the way to go for two reasons:

  • the whole installation needs to be certified, so I need to rely on an installer
  • for as much as I consider myself a skilled hobbyst, I would not feel comfortable going for the full DIY route. Especially since this will cost money and has to endure any criticism by my partners when things will go wrong :rofl:

So I will start asking around for quotations, can I ask your advice on what things should be a must in the first installation and thus save some costs in the beginning? (namely, what I need to install and foresee at the beginning and what I can postpone to later).
This comes to mind:

  • network topology (and conduit placement) since it will impact the masonry works: which one should I go towards?
  • switch/lights placement and basic logics
  • predisposition (mere empty conduits) for future integrations, i.e. roller-blinds, exterior webcams


  • complex logics: my understanding is that the base KNX modules would allow to control the single entities, then I should be able to modify the programming myself or expose them to other systems (HA?) and manage things there
  • fancy wall-mounted panels etc…

anything else?

Most important thing is sensors. You can’t automate good without having good sensors around. Consider placing ceiling mounted presence detectors in every room - or at least conduit etc. to get KNX there later.
Some presence detectors also support temperature or CO2 etc.

Thanks for the input. What usage could a room presence sensor have? Other than turning light on-off depending on the presence of a person?

Presence sensors (especially mmWave based) seem to be quite the rage around these forums lately. I personally find such fine grained per-room presence detection rather useless for my own use case, but that’s the point after all - every case is different. If you put in conduit now, you will be able to choose later. If you don’t run conduit, things get messy if you decide to add sensors down the road.

In general, as farmio mentioned, sensors are key for a smart home. Not necessarily presence detection only, but things like climate sensors, lighting sensors, PIRs, air quality, etc. Without sensors, your home is blind, so to speak. From smart climate control, over smart ventilation based on air quality to alarm systems, having places to put sensors keeps your options open for future developments.

Indeed I agree that putting sensors is key and for this I am already foreseeing one ethernet point in each room just in case.
In this case, being “pure ethernet” I already know that I should consider a star topology with the router (or floor switch) as a centerpoint.

But what I am a bit more confused is the KNX topology, which also will have an impact on the phsical placement of the conduits.
I can imagine a bus or star topology there but I could use some directions.

A Knx installation can be done as tree, star, open ring or a mix of these. Quite easy to install.

Presence detectors can’t only be used for lighting, but for climate purposes, shading (eg. turn auto-shading off when someone is in the room) and poor man’s alarm system. Also to remind if you forgot to close any windows when you are the last leaving the house (you’d need to know if someone is in any room) etc. in Knx this is usually done with ceiling mounted PIRs instead of mmWave. Some even have zones - so you can do different things depending on if you are sitting at the kitchen table or standing at the stove…

is there one to prefer in terms of scalability for the future? My best guess would be tree (or a bus with many sub-branches)