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When you decide to build or extensively renovate your home, you will need to do a LOT of planning. This series of posts will give you some insights on how to begin to plan your smart home installation.

The Old Way of Doing Things

Our homes weren’t smart until about 10, maybe 15 years ago (for some rare enthusiasts like me).

The old way was to run two circuits of power wiring on separate fuses to each room, one for lamps, the other for outlets. Then you would have the lamps directly hard-wired to the switches and the switches to the power circuit (using wires in cable conduits inside the walls). The outlets would be directly wired to the other power circuit.

For large loads (washing machine, oven, water heater) you would have a separate fuse and power circuit, again directly hard-wired to the corresponding outlet.

All the fuses and a RCD were collected in a main distribution box somewhere near the entrance of the house.

Pros

  • Simple to install
  • Minimal length of wiring, minimal costs

Cons

  • Very hard to make any changes after installation, everything is hard-wired
  • Very hard to automate
  • Very hard to log useful data

What Is a Smart Home Then?

For me, the defining feature of a smart home installation is the fact that hard-wiring of functions is, to the extent this is sensible, replaced with software and automation elements.

Instead of wiring a switch directly to the lamp the old way, the switch is wired to a controller digital input and the lamp is wired to the controller relay output. When we press the switch, the controller software senses this and switches the relay, turning the lamp on or off.

Hardwired v. Controlled
The Paradigm Shift

At first glance, this seems like a really roundabout way of doing things, but it opens all kinds of possibilities:

  • You can turn the lamp off automatically once the presence sensor is inactive for a while to save energy.
  • You can turn the lamp on automatically when someone enters the room, but only if the illumination sensor shows it’s dark in there.
  • If you are deaf, you can set the lights to blink three times if somebody rings at the door.
  • You can turn things (e.g. heat) on or off remotely, so you come home from a long trip to a warm home.
  • You can reuse the same sensors for different purposes, e.g. presence sensors can be used for alarms, energy saving functions and comfort.

The possibilities are really endless and can help you save money and energy, have more comfort, be safer, etc.

What Are the Main Features of a Well Designed Smart Home System?

Reconfigurability

We all know how we try to make plans and then life happens.

You want to use a different switch for a certain lamp? With a good smart home system, all you need to do is change a line of a YAML file. Adding many features often entails simply installing and configuring a plugin. A well designed system also allows easy hardware upgrades and system extensions (e.g. adding a room) due to it’s modular and distributed nature.

Reliability

Things break. A smart home will have many more parts than a traditional installations and you are certain to have a failure every now and then. It is important the system is built as resiliently as possible.

I cannot overstate the importance of good backup, which is the backbone of reliability in any software-controlled system. It is the difference between an utter catastrophe and an inconvenient chore once something breaks or you are hacked. Make at least daily backups of any relevant files locally (you need a NAS anyway) and invest in a good well-encrypted online backup service to backup at least the important files from there. I found IDrive to work on any Linux SBC and the pricing is reasonable.

Modularity is an important part of reliability—a set of several smaller subsystems will be more reliable, less complex, and easier to troubleshoot than an equivalent big system. There is also an added benefit that most of the overall system will continue to work despite a part being down.

Another important part is wiring. Wireless connectivity can be really helpful where wiring things is impractical, but you should wire everything else. This gives you several advantages:

  • No need for batteries. Batteries wear out and this is bad for two reasons: First there are the natural resources being wasted and secondly, a lot of e-waste comes from devices that are simply thrown away instead of replacing the battery (if that is even possible).
  • Wireless works most of the time. Wired works all the time.
  • Some devices need to be responsive: When you press a button, the lamp should light up in less than a second or you will think there is a problem. Wireless loses packets all the time and you will get weird delays/issues when you least expect them.

Sustainability

Sustainability has several dimensions:

Sustainable Use of Materials

Choosing the right system topology can substantially reduce the amount of work and materials needed. This will also have knock-on effects on reliability and reconfigurability.

Sustainable Choice of Platforms

To put it very simply: If you are building a system that needs to work for a couple of decades, you must actively avoid any closed source products!

15 or 20 years later, that fancy PLC will not be available to buy if you need to replace it. Even more, the programming software for it will likely not work on the future OS (Windows 17?). And since it’s all closed source, you can’t port or hack it. All the expensive gear and precious natural resources will go to waste and you will have to start almost from scratch.

Bought a cloud-enabled app-controlled EV charger? Read about Juicebox and imagine being locked out of your smart home because somebody ran their company into the ground and simply turned off the cloud computers.

What will work forever? Open source software (Linux, Home Assistant and a lot more), open hardware (any Linux SBC or PC, Modbus or MQTT relay/input boxes, etc.) and open industrial communication protocols/standards (Modbus, RS232, RS485, Ethernet, MQTT, and a lot more). If something breaks, these are cookie-cutter modules—even if the one you want to replace is not available anymore, just buy a similar one and reconfigure (RaspberryPi 12 is sure to happen someday).

Sustainable Use of Energy

As you are planning your home, remember that efficiency pays for itself quickly. Buy better performing machines, but don’t pay extra for gimmicks:

  • Better home insulation will be more expensive, but then you need a smaller and cheaper heat pump, air conditioning, etc., so it should pay for itself.
  • A heat pump does not need a fancy app to control it, just a Modbus interface for your system and the best COP you can afford.
  • Invest in ventilation with heat recuperation. Or live with mold. Forget about apps, choose the model with efficient motors and some kind of communication interface. An integrated CO2/VOC sensor is a plus, so you only run it when needed.
  • Buy an EV charger that will be locally controllable (i.e. it has a control interface) by your smart-home system so you can charge efficiently. Or build one yourself.
  • Some EVs will consume 12kWh/100km, some will consume 25. Buy what you need, but not more. Same size cars from different manufacturers can have very different consumption. Why am I including your car in this article about smart homes? It will be a major consumer of energy, but also has the potential for a LOT of optimization, from smart charging control to V2G. Most important: For the love of Earth, don’t replace it until it stops working or you really need a different one. Buying a new car every few years is easily the most expensive habit of your life and a colossal waste of resources.
  • Heating/air-conditioning is easily your biggest energy consumer. Install temperature and humidity sensors in all the residential rooms and make the heating controllable so you can only use the energy you really need.

Questions You Need To Ask Yourself

Having a smart home can save you money, increase comfort and safety, and make your life more sustainable, mainly by reducing your energy consumption. But there are some important questions:

  • Could you build it yourself, even if you choose to use a contractor?
  • If not, do you understand it well enough to communicate your desires, needs, and concepts to the contractor?
  • Do you trust the contractor?
  • Is the design clear and well-documented enough for somebody else to continue maintaining the system in case you want to change the contractor?
  • Are you able to reconfigure the system yourself after it is built or will you need ongoing support here as well? What about repairs?
  • Have you thought enough about the sustainability of the system?
  • Did you avoid pitfalls related to closed systems?

Be honest with yourself, the answers to these questions are important! Depending on them, your smart home can be an awesome thing or a source of SEVERE frustration. Good luck!

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