Sensory Overload – what does it cost to kit out a three bedroom home with sensors and switches on a budget.

The Smarthome Book

Ok so I have been running Xiaomi Aqara sensors (zigbee) for more than a year now and they have been brilliant. So much so that I’ve just bought another load. When this package arrived through the door, my girlfriend made her usual comment about me spending too much on tech etc. When I told her how much It all came to, she was genuinely surprised. These are really cost effective for what you’re getting, so I decided to let my imagination run free and see how much would it cost to deck out a modest three bedroom house with sensors and some essential automation equipment. I’m thinking the basics here in terms of equipment. I don’t included thermostats or alarms because they could cost anything from hundreds to thousands of pounds/dollars etc. I am referring to sensors, a control system which can interact with them, and some basic lighting options. *If you want to skip to the bottom you can see the complete buildout costed by item.*

Now in order for us to go through this, some assumptions need to be made.

Doors:

I am assuming we have one main front door, one kitchen back door, a patio door (single or double) and a garage door (not the big shutter, I’m talking about a walk through).

Windows:

I’m assuming that we would need sensors on the parts of the window that are large enough to fit through. I am discounting smaller windows that tend to be at the top which can open vertically. I’m also assuming that for most windows, you would have openings on either side and thus would want a pair of sensors on each double window i.e. on each pane.

Rooms:

I am assuming the average 3 bedroom house consists of the following:

Lounge or Living Room

2nd Reception room (can be study/dining room/games room etc)

Kitchen

Master Bedroom

Bedroom 2

Bedroom 3

Downstairs (Guest) Bathroom

Upstairs Bathroom

Loft/Attic and/or Basement/Cellar

Garage or shed

 

Motion Detection:

Where would we like to detect motion?

Under each bed (*3) for night lights or bedside lights

In a loft/attic to turn on or off a light when needed (saves reaching for a switch in the dark and prevents you leaving one on for days on end).

In a garage to turn on or off as a security measure as well as saving you leaving it on.

 

Water/Leak Detection:

Where would we like to detect a leak?

Under the Dishwasher.

Under the Washing machine.

Under the Tumble Dryer.

Under the Fridge.

Under the Freezer.

Under the boiler (which could be in a garage or in a cupboard).

 

How would we like to switch things on/off (lights, music, electronics)?

Switch locations:

2 x master bedroom (each side)

1 x bedroom 2

1 x bedroom 3

1 x by front door (turn off everything in the house when leaving with one press?)

 

Where would we like to measure temperature/pressure/humidity?

Lounge

2nd Reception

Master Bedroom

Bedroom 2

Bedroom 3

Garage

Loft/Attic or Basement/Cellar

 

Where would we like to measure vibration/tilt (drawer or cabinet open alerts)?

Where do you keep sensitive things:

Filing Cabinet

Gun Cabinet

Jewellery Box

Garage

 

Where would we like to be able to control lamps (socket)?

Lounge

Master Bedroom (each side)

Bedroom 1

Bedroom 2

 

Where would we like to be able to control Lights wirelessly?

Garage

Attic/loft or basement

 

I’ve summarised the above in a table at the bottom of this article. At first glance it looks like a pretty overwhelming list. If you break it down though, if you take a standard room like a bedroom, you’re in essence asking for a smart light, motion sensor, and contact sensors on the windows. You would know at any moment in time if the windows were open or shut and you could use the motion sensor to trigger a night light (under bed) or bedside light if needed. You would also know the temperature there.

Look at the kitchen. Here we would have a door sensor on the back door, window sensors on the opening windows (allowing for 2), and leak sensors underneath all appliances that deal with mains… washer/dryer/fridge/freezer/dishwasher. Is that totally over the top? Or is it common sense?

Lounge – one door sensor (for patio doors), windows sensors, a smart lamp socket, temperature sensor.

Attic – motion sensor and smart light.

Garage – Motion sensor, window contact sensor, temperature sensor and I’ve allowed for two vibration/tilt sensors in case someone has something of value there like a gun safe or a filing cabinet.

Front Door/Porch area – motion sensor, smart bulb and door contact sensor, smart switch to turn everything off when leaving

 

Which Sensors could we use? (I’ve used affiliate links which help support the blog (and my haribo habit!)).

Firstly I’d opt for zigbee where I could as opposed to Wifi. You’ll see if you stick on the wifi path, not only do most things need mains power, your wifi network is going to get quite large quite quickly, and most standard consumer routers are going to struggle. I’m opting for zigbee over z-wave because I believe that zigbee is currently (at the time of writing) winning the race and Google, Amazon and Apple have announced that they’re going to throw down behind it. That’s not to say that z-wave wouldn’t work, but I also think z-wave is significantly more expensive than what you can find for zigbee.

So without further ado, we look at the Xiaomi Aqara range:

 

Contact sensors:

These are extremely small, lightweight and easy to mount. They can be mounted on door or window frames and depending on how many you buy, they can be had for around $8.50ish each. We use these for showing the status of a particular opening. Combined with voice alerts after a certain time or phone alerts when the home is in away mode they are very useful. We’ve also enabled the ability to switch on appropriate lights as a security measure in a room if the sensor is triggered after a certain time in the evening. We don’t do this with upstairs lights however as if someone just wants some fresh air in the night, you don’t want them being blasted with the light. Instead we turn on the outside lights on the ground. That should be enough to concern any would be intruder.

Aliexpress

Xiaomi Contact Sensor
Xiaomi Contact Sensor

Temperature/Pressure/Humidity sensors:

Aliexpress

Again, very lightweight, small and portable. We have these throughout our home. They’re so small we can essentially balance them (with a small piece of tape) on top of regular light switches. They are extremely unobtrusive. You could easily just hide them on a shelf or on top of a piece of furniture. Depending on the thermostat / heating system you use, they could potentially be brought in to be used also. I’ve also seen online where people have modfiied these to use them with fridges and freezers. When the temperature has moved above a certain range, they’ve triggered alerts to the home owner and the contents have been saved.

Xiaomi Temperature/humidity/Pressure Sensor
Xiaomi Temperature/humidity/Pressure Sensor

Motion Sensors:

Aliexpress

These are also very small, we use ours througout our home under the beds so that when one of us steps out of the bed they trigger underbed lighting to come on. You can read more about the actual set up and the automation from this post here   We also have them in cupboards where they act as walk in wardobe lights. The minute the door is opened / motion sensed they turn on the lights in the cupboard. After a minute they go off again if no further motion is found. You could have one of these in the garage or shed. Should there be any motion the lights can come on (if you have a smart socket) as well as notifications sent to phones or voice assistants. This is useful if you add a timer function to it. I.e. if the garage or shed senses motion after dark then we send a notification to our LG TVs (via Web OS component) and the Voice Assistants in the lounge and kitchen announce that there’s motion in the garage or shed. Not only can this help to deter intruders by triggering the lights, but it also helps to prevent a family pet from being shut in.

Xiaomi Motion Sensor
Xiaomi Motion Sensor

Vibration/Tilt Sensors:

Aliexpress

I use these on certain drawers in the home. We have sensitive things in the drawer such as passports, emergency cash, various credit cards etc. If I am not at home and that drawer is opened, I want to know about it (the system is smart enough to know whether I am home or not and sends an alert to my phone if the sensor is triggered, as well as announces on the voice assistants that the drawer has been opened). I got this in when we had cleaners and workmen in as you can never be too careful, but this type of solution would also work if you have children and an alcohol cabinet, jewellery box or a drawer. They’re very light and can be stuck to the underside of a drawer or the inside of a door or safe. Again very cheap to use. You can also use one of these on a loft hatch. Whenever someone wants to go into the attic space, and they lift the hatch up, they automatically trigger the light to come on for a pre-determined time. I personally prefer to use motion sensors as it ensures that lights don’t go off when someone is up there, but this is another cheap and easy fix. These would also work well on a garage car shutter. Every time the door was being opened or lowered you could trigger various alerts or events. (forgot to take a photo, but they’re the same size as the temperature sensors).

Leak Sensors:

Aliexpress

Pretty self explanatory, they lay on the floor under the various appliances (I always place them towards the back where the inlet/outlets are) and as soon as any water touches them we immediately get alerted. The alerts for this come via email, phone and voice assistants as well as to the TVs (again via LG’s WebOS component). These leak sensors could be useful in other ways. You could potentially mount them in the bath at a certain height and as soon as the water reaches there, you could be alerted too. This could be good if you have children, or forgetful members of the family!

These are basically the same size as the other sensors. I.e. very small. (I didn’t want to pull out our appliances to photo this one, so i grabbed it from the web).

Xiaomi Leak Sensor
Xiaomi Leak Sensor

 

Smart lighting:

Here we have a multitude of options. In general for lighting outlets, I prefer to go with wifi/mains powered stuff. I’ve used Tp-Link, Teckin as well as Blitzwolf smart plug sockets. I also know you can get wifi enabled wall sockets (receptacles). Depending on the light you want to turn on, you could also opt for a smart bulb instead. Especially if you want coloured effects and other such features. The choice is really wide here. There are zigbee sockets you can use should you wish. Xiaomi have them. I did like the Blitzwolf SHP5 that I recently flashed to Tasmota. Not only did it have the usual mains outlet, but it also provided me with 2 USB ports that could also be switched on and off independently. You can read about how I did that here. The beauty of this solution is that imagine you use one by the bedside. Not only are you able to control the mains outlet (bedside lamp? Smart speaker? Alarm Clock?), but you also have two usb outlets that are controllable aswell (n.b. USB1 and USB2 turn on together, but the pair are independent of the mains outlet). You could use some USB powered LED lighting under / around the bed as nightlights. Failing that you can use the USB ports to charge smartphone/tablet. It’s a nice compact option.

Aliexpress

Blitzwolf SHP5
Blitzwolf SHP5

Smart Switches:

Here Xiaomi Aqara range has you covered again. We use these small zigbee buttons either side of the master bed. Each have been programmed in Home-Assistant/Node-red to toggle the nearest bedside lamp on or off (his and hers), but not just one short press. If you press it twice in quick succession it toggles the under bed lighting on or off, and if you press and hold it down for a “long press” it toggles both lamps on or off at the same time. We also have one of these smart switches next to the inside of the front door frame. We “long press” it before we leave the house which triggers the away mode and every lamp, bulb and specific socket (not the ones that need to be left on standby) turns off. It also triggers a flow in Node-red that if any of the contact sensors are open (i.e. door or window is open) the voice assistants tell us loudly. This is useful for security purposes.  If we push it normally it toggles the front porch lights on or off (these are already on a dusk til dawn sensor though, so it’s more for overide). Variant 1 is the newer type with the multi operation.

Aliexpress

Xiaomi Push Switch Variant 1
Xiaomi Push Switch Variant 1
Xiaomi Push Switch Variant 2
Xiaomi Push Switch Variant 2

All of these sensors are compatible with Zigbee routers and you do NOT need Xiaomi’s gateway to run them. I prefer this method as it means all control is local and I do not need to worry about the internet falling over or any Xiaomi products sending information back to the mothership. If you would like to know more about how you would go about pairing these sensors up you can read my post here where I bought a cheap $4 CC2531 zigbee USB stick (router) and flashed it with Zigbee2MQTT. This is just one method of using Zigbee though, there are also competing methodologies and USB sticks. There’s Conbee and Nortek sticks. The thing is these all work and with zigbee being a mesh network, it not only saves your usual Wifi network from being overloaded with devices, but if you incorporate some zigbee smart plugs around the house they can help to rebroadcast or repeat the network signal. This is what makes Zigbee a relatively cheap and easy to use solution. If you wanted to replicate what I’ve done here, you could find that you need to buy something more substantial in terms of zigbee router. As once you get above 40 devices, I’ve read online that the CC2531 starts to struggle. That being said it’s still a very solid option for starting out and I’ve had no reason to change yet.

 

Zigbee CC2531 USB Router
Zigbee CC2531 USB Router

The xiaomi sensors are very small, and have good battery life. Most of them contain watch style batteries and haven’t needed to be changed in the year that we’ve had them now. Of course depending on your situation YMMV. When it comes to swapping them out, you normally just use a coin to help unlock the rear and swap the battery. It takes seconds.

Xiaomi Motion Sensor Battery
Xiaomi Motion Sensor Battery

The control system:

The brains of the operation! We use Home-Assistant with Node-red. It’s a free solution, with no upfront or ongoing costs, unless you want to contribute to their Nabu Casa model which effectively allows Home-Assistant to reach the internet in a secure way and provides direct connection with Alexa, Google Home etc. I personally don’t need that and am more comfortable using OpenVPN if I wish to visit my network whilst away. You can run this software on pretty much anything nowadays. I started with it on a raspberry pi3, before moving it onto a docker installation on my Unraid home server. Now it runs on an intel NUC (6th gen) celeron that i picked up on ebay. The point is you can run it on whatever hardware you have laying around. For most beginners I would strongly recommend a raspberry Pi. It’s a good idea to keep it separate so that if your server goes down or your computer needs to be restarted, the rest of the home functions as normal (trust me, this is good for family approval!).

Raspberry Pi4
Raspberry Pi4

I would recommend if you do go down the pi route to look at the pi4 cases with the mini screen attached. They’re very usefulf for fault finding and also on the off chance you need to actually administer the pi, all you do is just plug in a keyboard and you’re good. It’s a lot easier leaving everything in situ rather than having to bring the pi out of it’s place and up to the desk.

You can find them here: Pi4 case and heatsink

 

Extras and Next steps:

Another product I am a huge fan of is the Sonoff 4Ch Pro2. These can be had for not much money and you can also insert Tasmota onto them easily enough. You can see the template here. I like this for various lighting in the garden. I prefer wifi here because the signal needs to be stronger to reach it. It can be positioned inside a weather proof box and is a great controller for scene lighting in the garden. It’s not very expensive and integrates very well with the rest of the house. It has 4 relays so can be perfect for people who own ponds i.e. you need control of the UV light, pump, lighting, and you still have a channel to spare. Cost is around $25-30 usd. They even have RF control so if you wanted to attach it to a keyring, you could have even greater remote control. It could be used in a control system for a garage door (if you order it with a keyfob). You could use one channel to control the car door (maybe you have a second), you could control the garage lights, front garden lights or even set the relay to control an input boolean which switches the house off or on depending if you’re coming or going. Literally the options are endless.

Sonoff R2 Pro (Aliexpress)

Sonoff R2 Pro
Sonoff R2 Pro

 

 

Now for the costs:

As promised, here’s the table summarised of what I think is worthwhile:

Table of Items
Table of Items

 

Which equates to the following (brace yourselves!).

18 Contact sensors (door+window) (10.95*18)  $    197.10
5 motion sensors (37.95 *4) + (10.32 *1)  $      48.27
5 leak sensors (12.91*5)  $      64.55
4 vibration/tilt sensors (11.05*4)  $      44.20
7 temp/press/hum sensors 41.79 (4) + 32.29 (3)  $      74.08
5 multi press switches (11.71 * 5)  $      58.55
7 sockets (dual USB) (14.24*7)  $      99.68
Zigbee Stick CC2531+debug cable (4.89+2.25)  $        7.14
 $    593.57

 

Now we still need to add the computer hardware but the cost of this varies massively. If it’s a raspberry pi 4 it’s probably another $60-80 by the time you’ve included the case and screen. Half the cost if you go with a pi3 and a simple $5 case. I also didn’t include the sonoff r2 pro (garden or garage control) that’s another $25-30.

Now whilst this taken together seems a large outlay, I want you to remember two things. Firstly, I needed to make some pretty large assumptions about what the average home has and might need. Your requirements could be fractional compared to what I’ve outlined above. On the flip side, yours might be magnitudes larger! Also the other thing I want to point out is that in the world of home automation an initial layout of $600 (or about £475 at this moment in time) for all those sensors and the ability to control that much in a home is actually pretty good value. I remember the old days when that amount of money would be lucky to get you a power supply at Crestron or AMX 🙂

 

I guess whether it makes sense for you or not depends on your needs and the depth of your passion for this hobby! I hope you found it useful, would be interested to hear your thoughts one way or another.

As a side note, if you are looking at a renovation or looking for wiring advice on a new home, you might be interested in my book that I recently published. It’s available in all the major book shops online as well as in hard copy. You can see more details here.

Cheers!

 

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