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Source: fotolia/Robert Kneschke

Three years with my smart home – a self-test

This article is about

  • The engineer and smart home fan, Andreas Schaller tested his private smart home from scratch. Read about his experiences and recommendations.

Changes in life open up new opportunities. When I started working for Bosch in Automotive Electronics, relocating into my new, rented apartment in Reutlingen, Germany, gave me a chance to install my private smart home from scratch – leveraging all my prior existing household appliances and devices.

Open source software and cheap hardware provided a low entry level for me, and after having worked for 15 years in consumer electronics, it was a fun, distracting project. Since then my smart home and I have been living together for three years, so I can come to a few longer-term conclusions. Let me first say it’s important to understand that the results are individual (rental apartment, daily life) and cannot be generalized. Now let me briefly introduce you to my set-up and what I’ve learned.

First things first: moving into a new environment allowed me to install two separate power circuits per room, one for the devices that need to be powered all the time such as refrigerator, router or landline phone, and one for those that can be switched off.

Statistics of yearly electrical power consumption of smart home Source: Andreas Schaller
Yearly electrical power consumption

Then, to use electricity as efficiently as possible, I created three different modes for energy management: night shutdown, wake-up alarm, and presence detection. Night shutdown starts every day at 1 a.m. and ends with the (too early) ring of my daily wake-up alarm. Connecting the alarm clock wirelessly allows me to personalize the system on a daily basis. I used the same principle for presence detection. My smart home system detects whether my mobile phone is logged in to my local WLAN and switches devices on or off accordingly.

Did you know that houses are the number one consumers of energy? So heating efficiency was next on my agenda. For managing my heating consumption, I needed to analyze the heating and cooling parameters. I think there is lots of potential for future smart home systems to automate this data mining step. Based on the three abovementioned modes of power consumption management, I switch to night temperature three hours before starting the night mode, e.g. at 10 p.m., and start heating to my desired room temperature again 90 minutes before my alarm clock rings. Finally, when leaving my apartment (as detected by the WLAN presence detection), my heating system automatically switches to the ‘out of home’ temperature after 15 minutes.

“Feierabend” means quitting time in German. It is composed of the nouns “Feier” (celebration) and “Abend” (evening), and was in former times used to denote the “Vorabend” – the eve, or evening before, a “Feiertag” (holiday). There is no direct literal translation in English.

The missing service for heating management in a rented apartment is what I often call the ‘Feierabend mode.’ How can I forecast my daily arrival time at home after work? The most straightforward approach was to track the WLAN logins and logoffs and calculate a usual quitting time from the data collated for each working day.

Statistics showing the yearly heating comsumption of smart home Source: Andreas Schaller
Yearly heating consumption

On the one hand, I wanted the Feierabend mode to increase my comfort, by making sure my apartment is at a comfortable temperature when I get home from a busy day at work. On the other hand, it soon was very clear that the Feierabend mode is also my biggest driver of heating costs: the better my Feierabend mode is defined, the more positive the impact on my heating costs, which split into 40% on weekends and 60% on weekdays. I am currently experimenting with different options using connected devices to improve this mode. For example, I’ve installed a dedicated smart home calendar to sync private calendar events that affect my usual quitting time. Another approach I’m currently testing is to implement a geofence application into my system to track my departures and trigger the heaters accordingly.

Statistics showing the average radiator valve for four different modes of smart home Source: Andreas Schaller
The four morning, Feierabend and night modes for heating consumption management

Despite power and heating management, the four modes defined can be used for additional comfort and security applications: heating shutdown triggered when opening windows, push messages for forgotten open windows, reminders to open windows at high humidity in rooms, and of course remote control of all devices via my mobile phone, ….

There are several lessons to be learned from the past three years:

  • A smart home installation driven by personal events is able to compensate the increased cost of electrical power and heating by optimizing consumption. As a tenant, I benefit from stable utilities charges and from the knowledge that my budget for them will not have to change.
  • For me, the most time-consuming activity was to analyze and model the heating behavior that fits my lifestyle and work habits.
  • Looking at my installation from an ROI (Return on Investment) perspective, it became positive in the third year.

Statistics showing the breakdown additional property expenses for smart home Source: Andreas Schalller
Breakdown of additional property expenses

As an engineer and smart home fan, I hope that in the future all device-related activities will be automated by different intelligent learning algorithms: all controlling events could be triggered by people’s activities and related to connected devices already in use e.g. carrying a mobile phone to work or setting an alarm clock at night. The combination of an intelligent environment at home, work or on the go, triggered by people’s activities and leveraged by connected devices, is what I think of as a real benefit of the Internet of Things.

Consider a smart home you want to live in – what would be your desired modes to make it more energy efficient, comfortable or secure? 

Curious to learn more about smart home solutions?

Find out how Bosch's room-climate solution directly controls TRVs.

Read Kai Hackbarth's explanations on important standards in the development of smart home solutions, such as OSGi.


  • 20. November 2015 at 8:39

    Someone mentioned this blog entry two days ago on twitter. It’s very interesting to see the influence of smart home technology for your heating. In my smart home, it was very useful to measure the outside temperature, room temperature and the single values I could get from my heating system. I used that information to calibrate the system. For a permanent control, my geothermal system with floor heating is to slow as to switch in a night or away mode. Nevertheless, I was able to cut down the heating costs by 50%. I strongly believe that my savings are so high because the plumber installed the system didn’t calibrate it correctly. However, I also believe that this is true for most of the heating systems as many plumbers have no time or the needed skills to do it correctly. It really needs a lot of time with a permanent measure and adjust loop, seeing the first actual influences of the modifications after 24-48h for newer and slower heating systems.

    For electrical devices, I haven’t really analyzed and optimized the power consumption by shutting them down. But I love the comfort a smart home provides like turn the lights on and off according to the detected presence or automatic control of the shutters (which is especially convinient during the summer months if you have big windows like we have).

  • 7. April 2014 at 18:46

    Thanks Ralph, TEDx Stuttgart was a great experience. Thanks again for helping organizing the event and all the best for 2014.

  • 7. April 2014 at 17:41

    If you are curious about Mr Schaller its home automation project and what more is possible you might be also interested to see him (and many other excellent speakers) speaking at TEDxStuttgart in February 2013:

  • 3. April 2014 at 10:26

    Hello Kai, could you please contact me by email (see Author Contact Box above ). We have a long backlog of already written blogs waiting to be released.

  • 3. April 2014 at 9:23

    Hi Andreas,

    would it be possible to create an additional blog entry that further describes the hardware & softwarestack that you are using?

  • 1. April 2014 at 15:18

    Hello BAFOMET, as I have written in the blog, for my rented apartment the electrical power and heating management is keeping my budget. The heating optimization has a better cost decrease leverage but also depends much more on the environmental conditions (outside temperature).

  • 1. April 2014 at 15:06

    This is very useful article. People are not sure if investment in smart home will ever reimburse and if so, then when.

  • 31. March 2014 at 16:21

    Hello Bruce, what is your personal experience? Do you see (or would expect) similar results?

  • 31. March 2014 at 11:54

    This is a great post – it’s interesting to see results from a personal experience. Thanks for sharing!

  • 28. March 2014 at 8:53

    Hello Achim, thanks a lot for your feedback to my blog. As a detailed feedback your questions can not be covered inside of the blog I will get back to you with a separate email.

  • 27. March 2014 at 9:27

    Hello, i have noticed your report with your 3 year experiences in a smart home and homeautomation..

    Can we see your implemented system in detail – homepage – documentation etc?
    Used operating systems, hardware, user’s surfaces – displays etc.

    I am working on “Homeautomation” since December 2013 and i am learning more day by day.
    Because you have more than 3-year experience, I think you can provide many hints and solutions.

    Here my first steps:
    http: //
    http: // / arduino_yun.html

    Since last week I am testing a 434 MHZ receiver to detect movement alarms and receiving window and door sensors.