A Comparison of the Popular Home Automation Technologies Chathura Withanage*, Rahul Ashok, Chau Yuen, Kevin Otto Future Living Lab Engineering Product Development Pillar Singapore University of Technology and Design Singapore *
[email protected] Abstract—Home automation systems represent the front-end of smart grids, where the energy monitoring and control operations are enabled through smart devices installed in households and residential buildings. There are many home automation technologies available in the market, and the users are left to select their choice of best technology. Proper guidelines to their selection currently remain low. Therefore, in this paper, a comparison of popular home automation technologies is presented from user perspective to fill this void in the research literature, and to empower the users with more details based on the current home automation market. X10, Z-Wave, ZigBee, INSTEON, and EnOcean are the home automation technologies compared in this paper. Two indices are developed as the outcome of this paper to represent the performance and affordability of these technologies, as a guideline to the potential users. We find these technologies fit out a tradeoff of higher performance and price (Z-Wave) down to lower performance and price (X10). With this understanding, appropriate choices can be made.
technologies are evaluated to provide indices as selection guidelines. We consider an affordability index and a multifactor performance index to compare these technologies. The Future Living Laboratory of Singapore University of Technology and Design is a test bed facility used to evaluate the operational requirements and performances of these home automation systems, and develop new systems and applications. The Future Living Laboratory network architecture is shown in Fig. 1. Z-Wave and INSTEON devices [9-10] are sharing the same network and there is a separate network for the ZigBee devices [4] as shown in Fig. 1. a) ZigBee Network
Index Terms--home automation; smart homes; sensor systems.
I.
INTRODUCTION
In smart homes, automation systems are used to monitor and control the energy usage of electrical appliances and equipment [1], and can be considered as the front-end of a smart grid. These systems can be connected to utility meters to form a smart grid or work as a standalone system. In addition to energy monitoring and control devices [2], there are many other devices that can be connected to the home automation systems such as motion sensors, temperature sensors, etc. to provide security, fire protection and various other benefits to the users [3].
b) Z-Wave and INSTEON Network
The smart home market is growing rapidly with the entry of more players in consumer electronics such as Samsung and LG [4], as well as IT companies such as Google to the already blooming market. These companies have announced products and services that could rapidly grow the smart home industry. In the current home automation market, there are several popular technologies [6-7] competing for market share. This includes X10[8], Z-Wave [6, 9], ZigBee [6], INSTEON [6, 10], and EnOcean [11]. The result has been a plethora of choices to the potential consumer. However, any guidelines or comparisons are not available to support the user’s decision making. Users are left to choose technologies they find available or know about. Information to help users make cost and performance based decisions are not available. Therefore, using a testing facility, these
Figure 1. Network architecture of the Future Living Laboratory
This paper consists of five sections. In Section II, brief introductions are given about the functionality of these technologies. Evaluation is done in Section III and indices are introduced in Section IV. The paper ends with conclusions and future works given in Section V.
II.
POPULAR HOME AUTOMATION TECHNOLOGIES
A. Z-Wave Z-Wave [9, 16-17] is the most widely used technology in home automation systems, and by far the most widely accepted technology [15]. It offers good network reliability and stability (see Fig. 2a for a Z-Wave motion sensor). ZWave is one of the oldest available home automation protocols. The best feature of Z-Wave devices is their crosscompatibility among different branded systems [9]. Each ZWave device has a unique network ID and each network has a unique identification thus making the system secure [16]. Z-Wave is a mesh protocol, and thus the devices can talk to one another. Z-Wave operating frequency varies with the region; the frequency is 908.42 MHz in the US and 868.42 MHz in Europe [9, 15]. Also, the signal range offered by Z-Wave is high, in the range of 30 meters, and it is possible to extend the range of devices by using them as repeaters. As the signal passes from one device to another, it gains a range of another 30 meters. This process is called hopping, and it can be done to extend the signal using a maximum of 4 devices. However, beyond 4 devices, the Z-Wave protocol terminates the signal (Hop Kill) [9, 17]. B. Zigbee ZigBee is an IEEE 802.15 standard used in home automation technology and very closely resembles Bluetooth and Wi-Fi standards [18-19]. Zigbee devices are attractive largely because of its low power consumption and open specifications which makes the devices ideal for battery operated uses. Zigbee, like Z-Wave is a mesh protocol, where devices can talk to one another, and can act as repeaters [18]. Even though with so many advantages, the technology has not gained a large market share, mainly because of the incompatibility of devices among many different vendors. However, Zigbee proves useful in research, with many universities developing devices such as TelosB, from University of California Berkeley (see Fig. 2b) that can be used as part of a wireless sensor network to monitor environmental conditions [12]. TelosB motes are relatively inexpensive, can be used as a transmitter and a receiver and useful for inexpensive custom sensors.
a)
b)
Figure 2. Z-Wave motion detector and a ZigBee TelosB mote used in the Future Living Lab
C. X10 X10 [7, 20-21] is one of the oldest available home automation standards. The technology is still in the market despite tough competition from newer standards. There are reportedly 10 million X10 devices in US alone. An advantage of X10 is that it can use either wired power line or wireless radio communication methods. However, the transmission of messages occur one command at a time. This is one of the biggest disadvantages of X10 because multiple, concurrent X10 signals may lead to
decoding issues resulting lost commands [8]. Nevertheless, X10 is inexpensive and many devices are available. D. INSTEON INSTEON [10] is designed to integrate power line systems with wireless system, and was developed to replace the X10 standard. It is designed such that it enables devices, whether sensors or switches to be used together using power line and/or radio frequency. Other than X10, this is the only technology that communicates via both wireless and powerline technologies [22]. Another advantage of INSTEON [10] is its partial compatibility with X10 devices. INSTEON and X10 commands are not similar, but the INSTEON driver chipset has the capability of responding to X10 messages [10] and therefore can communicate with X10 devices. The transmission of data occurs at 1131.65 KHz for powerline devices and 904 MHz for wireless devices [10, 22]. In an attempt to make interoperable INSTEON devices across different platforms, an alliance has been formed (similar to Z-Wave alliance) which includes many INSTEON product development organizations and some Fortune 500 companies [10]. E. EnOcean EnOcean [11] is one of the newest technologies in home automation, mainly aimed at zero energy consumption through energy harvesting. The unique beneficial feature of EnOcean devices is their ability to work battery-less and still having the ability to communicate wirelessly. This is achieved by means of micro energy converters along with ultra-low power electronics [22-24]. Early designs of EnOcean devices used piezo electric generators but were later replaced by electromagnetic energy sources [23]. Because the devices are self-powered, the maintenance is minimal. Radio interference is also minimal as it operates in the less crowded 315 MHz band [11]. According to EnOcean Alliance [11], their sensors have been installed in over 250,000 buildings, far less than X10 but nonetheless growing and not inconsequential. III.
THE EVALUATION
We compared these standards on several criteria related to performance and affordability (see TABLE I). Several of the comparisons are based on the tests conducted at the Future Living Laboratory in Singapore University of Technology and Design (SUTD) as well as reviews from technology websites and research papers. The popular home automation websites and previous publications [13-15] were used to help identify the key performance factors listed. Each performance factor was given rating on a 0-3 scale as indicated in TABLE I. The performance factors were then combined into an overall Performance Index. In addition, an affordability index was obtained using the retail prices of the home automation devices at various locations globally. More details about the performance factors, prices, performance index and affordability index are given in the following subsections. Affordability index is calculated based on the cost of a system consisting of four smart switches, a gateway, two occupancy sensors and a temperature sensor.
Properties
TABLE I. THE COMPARISON AND RATINGS Released (Year)
Z-Wave 2001
ZigBee 2004
Inventor
ZenSys Corp.
ZigBee Alliance
Standardization
Proprietary
Primary Markets
Home Automation
IEEE 802.15.4 Industrial Automation, Research, Home Automation, Telecommunications, Healthcare
Performance Factors
Communication Mode System-On-Chip Solution Encryption Energy Usage Data Rate Two-way Communication Transmission Range Inter-brand Operability Number of Certified Devices Ability to work as Repeaters Ease of Installation Performance Index Affordability Index
X10 1975 Pico Electronics Proprietary
INSTEON 2005
EnOcean 2008
Smartlabs Inc.
EnOcean GmbH
Proprietary
Proprietary
Home Automation
Home Automation
Industrial Automation, Home Automation
RF
RF
RF, Power Line
RF, Power Line
RF
Yes
Yes
Yes
Yes
Yes
128-bit AES High (1) ~ 40 kbps (3)
128-bit AES Medium (2) >20 kbps (3)
No High (1) 20-200 bps (1)
No High (1) ~ 2000 bps (1)
ARC4/AES Nil (3) 125 kbps (3)
Yes (3)
Yes (3)
No (0)
Yes (3)
Yes (3)
~120m (3)
~60m (2)
~30m(2)
~120m (3)
> 20m (2)
High (3)
Medium (2)
Low (1)
Medium (2)
Medium (2)
>600 (3)
500 (3)
600 (3)
Yes (3)
Yes (3)
No (0)
Yes (3)
No (0)
Easy (3)
Medium (2)
Difficult (1)
Easy (3)
Medium (2)
0.916 0.34
0.792 0.212
0.375 1.00
0.75 0.362
0.75 0.46
A. Energy Usage One performance factor was the energy use of the devices. EnOcean is the unanimous winner in this category, and therefore assigned a value of 3. It does not require any batteries and is mainly aimed at energy harvesting. It does this by making use of the minor changes in pressure, motion, temperature and vibration to create electric power. ZigBee is the next most efficient, with the devices employing a sleep mode when not in operation thus minimizing the energy usage. ZigBee is thus given a rating of 2. ZigBee is developing a new feature called Green Power which can make the devices self-powered similar to EnOcean. The other devices, namely ZWave/INSTEON/X10, are not as good in terms of energy usage. They are assigned ratings of 1 each. B. Data Rate A second performance factor is the data rate. ZigBee has a maximum of 250 kbps using offset quadrature phase-shift keying, and exceeds other technologies by a wide margin. However, the European version of ZigBee has a data rate of around 20 kbps only [25].EnOcean has a data rate of approximately 125 kbps. Z-Wave has a data rate up to 40 kbps. The data rate for X10 is much lower in the order of 20 to 200 bits/second thus confining the technology to ON/OFF operations. Powerline data rate for INSTEON is
approximately 2000 bits/second. However, the wireless communication occurs at more than 20 kbps. Based on the above observations, ZigBee, EnOcean and Z-Wave (all having data rate more than 20kbps) are given ratings of 3 each. INSTEON and X10 are given ratings of 1 each. C. Two-way Communication Another important performance factor is the ability to both send and receive data. X10 devices have no provision for two way communication. Therefore, there is no acknowledgement for the commands sent, and thus assigned with 0 rating point. However, Z-Wave, ZigBee, EnOcean and INSTEON devices provide two-way communication and commands sent are acknowledged; and thus assigned with rating points of 3 each. D. Transmission Range Another important performance factor is the range of communication. INSTEON and Z-Wave outdid other standards with 30 meters for a single hop. Further, each ZWave/INSTEON device can act as an RF repeater and the commands can route through up to 4 devices before the protocol terminates the signal. This gives a maximum range of up to 120 meters. They are assigned with a rating point of 3 each.
ZigBee has a transmission range of more than 10 meters. It allows hopping and has the capability to send the signal up to 6 nodes before the commands are lost. This allows for a total of approximately 60 meters. EnOcean has a data range of more than 20 meters. These two are given rating points of 2 each. X10 is primarily a wired protocol, but there are wireless devices available for 900MHz RF communication. These are generally 30m transmitter/receivers. Based on the above observation, X10 is assigned with a rating point of 2. E. Miscallaneous Factors: Other factors for performance index calculation include ease of installation, ability to work as repeaters, inter-brand operability and number of certified devices. Ease of installation is one of the main factors as the ability to retrofit can ease the burden on the users. Especially, users living in rental or leased properties are greatly benefitted by the wireless plug and play devices, which can be easily retrofitted without touching the building interior or exterior. The factors are assigned with values as given in TABLE I. PERFORMANCE AND AFFORDABILITY INDICES
A. Performance Index Calculation There are many factors related to a technology’s performance. A single composite performance index is sought on a 0-1 scale. A perfect scale is 1 and rated best performing on all factors. The performance of the technology was calculated based on the rating points obtained from the previous section. Performance Index = ( (
!"!
) ! ##
%$)
The Affordability Index is calculated using the formula shown below. Affordability Index =
, - # . .
%
#
% / # 01# !
"
#
$ #
(2)
#1# !
The lowest total cost system is $170 for an X10 system. The calculated affordability index values are listed in TABLE I. C. Performance-Affordability Tradeoff Ideally, a technology with both high performance and affordability index would be preferred. This would fall on the top-right corner of the plot given in Figure 3. In reality, such a technology doesn’t exist and instead a priceperformance tradeoff is necessary.
(1)
The maximum permissible rating point for each factor is 3. Since there are 8 factors, the denominator of equation (1) becomes 24. The numerator is a summation of all the rating points assigned to a technology as detailed the previous section. The calculated values are shown in TABLE I. B. Affordability Index Calculation A second composite index is sought based on affordability. This index is calculated based on the cost required to purchase a basic system (consisting of a controller, four smart switches, two occupancy sensors and one temperature sensor). Since installation costs are the same for all technologies, labor costs are not included. X10 has been around for quite a long time, and therefore devices running on X10 technology are available for as low as $25. X10 controllers are available for $30 and sensors are available for prices ranging from $30 to $50. Therefore, the total cost of a basic system would be approximately $170. Z-Wave smart plugs cost around $40, and their controllers are available for $200. Sensors are available from $50. The total cost would thus be around $500.
Performance Index
IV.
INSTEON hubs/controllers are available in the market for approximately 120$, and smart plugs are available for $50. The prices of sensors start at $35. This makes the total cost hover at around $470. EnOcean USB gateways are available for $30 and push button switches are available for $35. Motion sensors are slightly expensive at around $80, while the temperature sensor can be bought for $30. The total cost would be approximately $370. ZigBee devices are slightly expensive compared to others. Their controllers cost around 270$ and other devices are available in the range $40 to $100. The total cost would be around 800$. However, ZigBee TelosB motes for research and development purposes are available at 60$. The costs of the devices are approximate indicative values and vary depending on the market, vendor and country.
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Z-Wave ZigBee X10 INSTEON EnOcean 0
0.2
0.4
0.6
0.8
1
Affordability Index
Figure 3. Performance Vs Affordability
X10 is low cost, but lower performance. Z-Wave is expensive, but high performing. Z-Wave is better compared to ZigBee based on overall price- performance and might be preferred. However, ZigBee has a unique feature of being very open, and so might be preferred solely on that basis.
V.
CONCLUSIONS
In this paper, a comparison of popular home automation technologies is presented. Performance and affordability factors of home automation systems were identified and rated by the researchers of Future Living Laboratory. Z-Wave is the leading technology in terms of performance, and is widely accepted in the market despite being slightly costly than ZigBee systems. The main advantages of Z-Wave devices are flexibility and security. Features like mesh network capabilities, upgradeable firmware and remote device diagnostics make it interesting. Furthermore, Z-Wave makes an attractive automation standard for professionals and researchers who work on home automation technologies, given controllers with open APIs. If cost is not a great concern, Z-Wave is the clear winner. ZigBee has been a preferred technology by many, mainly because of the fact that it is an open standard. In addition, ZigBee offers high data security and reliability, and strong data encryption capabilities. But, the major disadvantage is its noncompliance by different manufacturers. However, ZigBee has the potential to prevail as the market expands. There are many off the shelf ZigBee development kits available for developing prototypes and so ZigBee is ideal for research related activities. INSTEON holds good for users who are migrating from the old X10 standard, as it allows integration of both RF and power line technologies for networking. INSTEON network operate in a mesh fashion and can work as repeaters, increasing the overall transmission range. The installation of INSTEON devices is slightly easier and the devices are highly responsive. However, its major disadvantages are limited number of vendors and certified devices available. EnOcean scored well in the energy usage category, with the devices being self-powered. However, its reliability is low, and these devices neither work in a mesh network nor have the capability to work as repeaters. The technology is comparatively new and holds a promising future given the research activities underway to improve the system.X10 is the cheapest among the considered, but the technology is becoming obsolete. As costs come down on the new technologies, the price advantage will dissipate. As the home automation market expands, each of these standards will undoubtedly maintain their market share. Therefore, hybrid networks consisting of different standards are a likely future scenario. ACKNOWLEDGMENTS This work was supported by a research grant sponsored by the Energy Market Authority of Singapore, and from support from the SUTD-MIT International Design Centre (IDC) (idc.sutd.edu.sg). Any opinions, findings, or recommendations are those of the authors and do not necessarily reflect the views of the sponsors.
REFERENCES [1] W. H. E. Liu, and D. Pearson, "Consumer-centric smart grid," in Proc. 2011 IEEE Power Engineering Society Innovative Smart Grid Technologies (ISGT) , pp.1-6. [2] S. Ahmad, "Smart metering and home automation solutions for the next decade," in Proc. 2011 International Conference on Emerging Trends in Networks and Computer Communications (ETNCC), pp.200,204. [3] F. Suba, C. Prehofer, and J. van Gurp, "Towards a Common Sensor Network API: Practical Experiences," In Proc. 2008 SAINT International Symposium on Applications and the Internet, pp.185,188. [4] "CES 2014: Samsung and LG showcase their vision of 'smart' homes | NDTV Gadgets," http://gadgets.ndtv.com/others/news/ces-2014samsung-and-lg-showcase-their-vision-of-smart-homes-469844. [5] "Google Nest Acquisition: How Nest might transform Google advertising | BGR," http://bgr.com/2014/01/14/google-nest-acquisitionprivacy-advertising/. [6] C. Gomez and J. Paradells, "Wireless home automation networks: A survey of architectures and technologies," IEEE Communications Magazine, vol.48(6,) pp.92-101, Jun. 2010. [7] J. Walko, "Home Control," Computing & Control Engineering Journal, vol.17(5), pp.16,19, Oct.-Nov. 2006 [8] "X10 devices and standards," http://www.x10.com. [9] "Z-Wave devices and standards," http://www.z-wavealliance.org/. [10] "Insteon devices and standards," http://www.insteon.com/. [11] "EnOcean devices alliance.org/en/home/.
and
standards,"http://www.enocean-
[12]"TelosB Datasheet," http://www.willow.co.uk/TelosB_Datasheet.pdf [13] "Tom's hardware http://www.tomshardware.com/. [14] "About networking protocols, http://compnetworking.about.com/.
technical
standards
reviews,"
and
reviews,"
[15] "Home automation devices , reviews and case studies," http://www.vesternet.com/resources/feature-comparison. [16] M. Knight, "Wireless security - How safe is Z-wave?" Computing & Control Engineering Journal , vol.17(6), pp.18,23, Dec.-Jan. 2006. [17] P. Amaro, R. Cortesao, J. Landeck, and P. Santos,"Implementing an Advanced Meter Reading infrastructure using a Z-Wave compliant Wireless Sensor Network," in Proc. 2011 3rd International Youth Conference on Energetics (IYCE) , pp.1-6. [18] Batista, N.C.; Melicio, R.; Matias, J.C.O.; Catalao, J.P.S., "ZigBee wireless area network for home automation and energy management: Field trials and installation approaches," Innovative Smart Grid Technologies (ISGT Europe), 2012 3rd IEEE PES International Conference and Exhibition on , vol., no., pp.1,5, 14-17 Oct. 2012 [19] A. C. Olteanu, G. D Oprina, N. Tapus, and S. Zeisberg, "Enabling Mobile Devices for Home Automation Using ZigBee," in Proc. 2013 19th International Conference on Control Systems and Computer Science (CSCS), pp.189-195. [20] J. E. Kim, G. Boulos, J. Yackovich, T. Barth, C. Beckel, and D. Mosse, "Seamless Integration of Heterogeneous Devices and Access Control in Smart Homes," in Proc. 2012 8th International Conference on Intelligent Environments (IE), pp.206-213.
[21] L. Y. Lin, M. C. Cheng, S. M Yuan, "Standards-based User Interface Technology for Universal Home Domination," in Proc. 2006 International Conference on Hybrid Information Technology (ICHIT), pp.298-307. [22] M. Zareei, A. Zarei, R. Budiarto, and M. A Omar, "A comparative study of short range wireless sensor network on high density networks," in Proc. 2011 Asia-Pacific Conference on Communications (APCC), pp.247-252. [23] J. Ploennigs, U. Ryssel, and K. Kabitzsch, "Performance analysis of the EnOcean wireless sensor network protocol," in Proc. 2010 IEEE Conference on Emerging Technologies and Factory Automation (ETFA), pp.1-9.
[24] A. Lottis, D. Hess, T. Bastert, and C. Rohrig, "Safe@home - A wireless assistance system with integrated IEEE 802.15.4a localisation technology," in Proc. 2013 IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems (IDAACS), pp.461-467. [25] "ZigBee standards and devices," http://www.zigbee.org/Standards/Overview.aspx.
