What is a smart home ?
A smart home has the following characteristics:
In a nutshell, a smart home saves you power, energy, effort and money while improving your quality of life as well as giving you the freedom to use it wherever you are.
A lot of people have written thousands of pages about Smart Homes and what makes this page any different ? Because it is written by one who actually created a smart Home from the ground up. It tells you how you can convert a dumb house into a smart home with the current level of technology. And in writing this page, I have tried to keep it using Platform agnostic devices. You can buy the devices from any vendor and still control them using your mobile phone or your favorite voice control device – Alexa.
Energy Saving Smart Home
Smart homes save power and energy as a natural corollary of being smart. Before you start, take a look at our Power saving Calculator tool here. It tells you at one glance the amount of power you can save if you adopt the techniques listed here. You input the number of hours your intended appliance runs per day and the cost of power. You can add up to 3 devices at a time and the tool will tell you the cost of operating the devices for a month.
Switch your lightings to LED bulbs: A normal incandescent bulb of 100 W provides 1600 lumens (unit of light output measurement) and has a life of about 1000 hours. If you swap out the incandescent bulb with a 14 W LED bulb, it will almost provide the same light output but saves you 86 W of energy and has a life of around 40000 hours.
Cost of using 14 W x 10 LED bulbs @ 5 hours a day: (assuming 11 c per kWh) for a month: US Dollars 3.30
Cost of using 100 W x 10 incandescent bulbs @ 5 hours a day: US dollars: 16.50
You can see that you save 500 % in money spent on the energy cost.
Now add a touch of ‘smartness’ by turning on the light when you need it. Instead of keeping the lights turned on at dusk and running the lights all through the night, turn on the lights only when there is someone. This calls for motion sensors/ occupancy sensors to control the lights.
Motion sensors are of 2 types: PIR and RADAR (Radio Detection and Ranging). PIR (Passive Infrared ) sensors work by detecting the infrared energy emanating from humans and control the light. It uses a Fresnel lens to focus the energy into the sensor. Switches fitted with PIR sensors work well under most situations. But they have a draw back – the sensitivity of detecting people drops with the rise in ambient temperature. In other words, you will have to flail your arms to trigger the PIR switch in summer where the ambient temperature rises. Another drawback of PIR motion sensor is if the object sensed remains motionless, the PIR switch may turn off.
The RADAR (microwave) sensors work with microwave frequencies – 5.8 GHz to 24 GHz which can detect motion even through wooden doors, glass and light partitions. And they are not temperature sensitive like their PIR counterparts. If you are worried about the microwave radiation, you don’t need to worry. They output less than 1 milliWatt continuously . Compare this with your smartphone which can output 100 mW. Your microwave oven puts out more than 650 W of microwave energy within its shell.
A high end RADAR sensor device operating at 24 GHz has increased detection range, reduced false alarms and better detection of humans and large mammals. Besides the technical advantages, RADAR sensors also can be hidden behind surfaces unlike the PIR sensors which depend on a visible round Fresnel lens to detect.
These Motion sensor Switches also contain light sensors built-in so that they are not turned on during the day time. So these devices can be permanently left on. In quiescent mode (when the lights are not on) they consume low power: 0.2 – 0.9 W
Wifi Smart Switches:
These Wifi Switches are the basic building blocks of smart homes in a way. They provide you the convenience of controlling them through your mobiles or your voice: Alexa. That is not all. You can add scheduling to control the devices connected through them. These Wifi Smart Switches come with smart phone apps which allow you to add schedules and create a scenario to control a group of them. For example, Itead’s Sonoff Pow R2 is a smart Wifi switch which also doubles as a power monitor – showing the power consumption. The mobile app will show the power usage for 100 days. That is not all. You can even set the Wifi Switch to turn off the power if it exceeds certain threshold.
What this means is, if your HVAC compressor is overloaded for some reason and draws high current, the Wifi switch can turn off the power protecting the motor as well the wires feeding the motor. I will plug in real time values here : A conventional Air conditioner 1.5 ton compressor draws typically 9 A in a 240 V supply. If it draws 12 A or above continuously it indicates that something is amiss. Your miniature circuit breaker (MCB) if suitably rated should trigger a shut down.
I use a booster pump located in the terrace to add pressure to the water supply. The booster pump is connected through a Sonoff Pow device which is controlled by Alexa. If it is not for this automation, I would never have considered the pump in the first place. As an added bonus, this 10 $ Sonoff Pow device tracks the Electricity consumption over a period of time. I like to keep a watch on the power consumption of all my gadgets.
We have mentioned about Home Automation using inexpensive Wifi Switches here
We added schedules and control the lighting through our own local server. Trust me on this – these devices have saved me time, effort and tons of energy.
Wifi Standard: Most of the Wifi Switches, Wifi controlled Lights, Wifi Controlled Thermostats and other Wifi gadgets use the IEEE 802.11 b/g/n operating in 2.4GHz which is a good thing. The frequency 2.4 GHz allows you to have comparatively longer range of operation than the 5 GHz band. Anyway the speed of operation is not so important for our control purpose. You can have a dozen or so wifi appliances connected to the Wifi Router with no ill effects. The interference attributed to this 2.4 GHz band arising from microwave ovens and cordless phones won’t be enough to cause any malfunction usually.
Wifi Security: If you have many of these Wifi Appliances in your smart Home, use a separate router for them connected through your main router. Use WPA2-PSK for encryption. Use a complicated password for this router which is not used anywhere else. The idea is in case someone hacks into your smart home router, they can’t compromise your other activities.
I have used White listing of MAC addresses of all the devices. It is an extra step. Every step you add to the complexity of your smart home, it is an extra effort required on the part of the bad guys to penetrate your network. It is one of my jobs to harden servers from malicious entities in the last 20 years. I know what I am talking about. No hacker will be interested in hacking a home network which controls a handful of lights. Your threat perception may vary.
These Wifi appliances connect to the manufacturers’ server for storage of directives and 2-way communication. Most of the time they work as intended. But if you have problematic net connections, you should consider setting up your own local server. An old laptop, desktop computer or the low cost Raspberry Pi or Arduino will be sufficient to run a basic linux OS which can control all your Wifi Appliances of your Smart Home.
Voice Control: These Wifi Switches and control units are compatible with Amazon Echo, Echo Dot, Google Home, Google Nest and IFTTT.
These Personal Assistants can help you to control suitably equipped devices through your voice. Just say "Alexa Turn on Lights" and in the middle of the night your bed room light is turned on to help you go to the Restroom.
We have used a our NAS server for controlling our smart home for almost 9 years. We just keep updating our Wifi appliances every time something new comes up. Even in the absence of any internet connectivity, the local server will keep the Appliances well under control all year long.
It does the following things amongst others:
What if we go away for some days ? No problem. I issue a command to the server ‘Away’ mode. On activating this mode, the server blocks the water heater, Air conditioner and the kettle but continues to issue the normal commands to other Wifi appliances as usual. Some of the lights controlled by the server will get activated after 6.00 pm at random intervals and turn off on their own to simulate some presence to the outside world.