Internet of Things

Smart Home

Beginning of 2012 ASC started to install a Smart Home environment. The system consists out of an AVM Fritz Box 7390 plus the Home Automation Software FHEM, which is provided by AVM in its Lab Area.

For the sensor network ASC decided to go for the EVL FS20 System, which is based on 868 Mhz. Even the FS20 standard has some drawbacks (not IP based, no bidirectional communication, .... ) it is a rather cheap solution to implement ASCs first use cases ( weather station on the balcony, energy management, automatic heating,  ) and to analyze their benefits.

After getting used to the system by installing the weather station solution, including a daily private email service, ASC started to look into energy management. The picture below shows the yearly energy cost distribution in % before the ASC energy management was installed.



Figure 1:  Energy Distribution by Activity w/o  ASC Smart Home Environment

An interesting feature of a Smart Home Environment is switching devices depending on different sensor values.  To realize energy savings an important information is to detect if a person is at home or not. To do this the mobile phone is used as a sensor itself.  Every time a resident phone is detected by the WLAN router the sensor status is set to “At Home”.

Figure 2:  Energy Distribution by Activity with the ASC Smart Home Environment installed

In the ASC Smart Home environment the “At Home” feature reduces energy costs for the following activities:  Computing, Entertaining and (some) Lightning. Altogether a 3% reduction potential of the yearly energy cost could be identified and is currently realized (equivalent to a yearly 17 kg CO2 saving). The compensation of the complete system costs will take about 4 years.

As the next step the Smart Home Environment has been extended by an automatic heating control system.  First of all ASC identified that 2 heaters provide 85% of all the energy to heat all the rooms during one year.

Figure 3:  Heat Distribution during one year for all rooms

At least these two heaters have to be integrated into the ASC Smart Home Environment to fully automate the heating system and generate any kind of savings. Analyzing the temperature drift during the day it turned out that the maximum drift is about 12% of Tmax(room) for:  T outdoor = T min @night= 30% T room. Therefore a 12% gap is used as the default distance between the different temperature settings.

To cover all daily activities the solutions consist of 4 different scenarios:

1. Window Open
2. Weekend @Home
3. Week @ Home
4. Not @ Home

Figure 4:  ASC Smart Home Environment - Heating Scenarios

The above system has been successfully implemented and tested.  Now we have to wait for the next winter to compare the operational heating costs with the € vales of last year.