Articles and whitepapers

Open Protocols for Smart Home Applications (3/8/2007)

By Chris Irwin, Tridium Europe

The technology needed to link the functionality of various systems for heating, lighting, security and entertainment to create so-called 'intelligent' homes, has traditionally been both expensive and complex to engineer. This means that smart home systems, such as those by US-based AMX and Crestron, have been almost exclusively the preserve of the rich.

There have been a few more affordable systems such as Comfort/Cytech used mainly by the 'hobbyist' market, that is, people with sufficient technical knowledge and motivation to do it themselves. The oldest residential 'standard' used by this market is X-10, which is a mains signalling protocol (powerline) enabling a range of mainly plug-in modules to be grouped and controlled remotely.

X-10 products have the advantage of being relatively inexpensive, but their functionality is somewhat limited and there have always been issues with the protocol's reliability due to the effects of mainsborne interference.

The vast majority of affordable products for home applications tend to be single function - performing either lighting OR security OR heating control, and are rarely networked. However, over the last five years or so, a new breed of manufacturers has evolved that specialises in whole-house automation systems. Companies in Belgium, Germany, Italy, Spain and elsewhere in Europe have responded to an emerging market for more affordable controls that can be networked together to manage all the lighting, heating and security in the home.

Obstacles to adoption

Compared to its European neighbours, the UK has lagged behind in terms of interest and adoption of integrated smart home systems, but as people in the developed world invest more in their homes, and are becoming more accustomed to smart electronics in every aspect of their lives, expectations for the home are also rising in the UK.

The market for smart homes, although growing, remains a tiny fraction of the overall homes market, and there are good reasons why this is so. The first is the cost; even most of the more affordable systems will cost the homeowner several thousand pounds. Secondly, most systems use low-voltage wired networking, and so are only suitable for new buildings since the hassle and cost of retrofitting a wired system is usually prohibitive. A third reason is that most of the systems on offer use a proprietary protocol for their communications, so that all the devices have to come from the same manufacturer and cannot be mixed with devices from other systems. This has been a major barrier to widespread adoption because developers and home owners are fearful of being locked into a single manufacturer with the risk that the products may not be supported in the long term, or that they may be unduly expensive to replace.

Open initiatives

To address such concerns there have been various initiatives by manufacturers to create open standard protocols, and these have met with some success. Of these, EIB (now called KNX, developed in Europe), is the mostly widely used in the residential market, with LON powerline also attempting to gain a share. EIB uses twisted pair wiring to enable a variety of devices (mostly lighting orientated) to be networked together and managed in groups, both remotely and centrally. LON offers a similar capability with more flexibility, and the powerline version avoids the need for low-voltage wiring since the signalling is over the power wiring of the home. LON is much more widely used in the commercial market and there are hundreds of manufacturers offering products. However, only a very small proportion of these are suitable for home applications.

To complicate things further, a new generation of proprietary wireless lighting and security systems have also become available, to address the need for easy installation in retrofit applications, and there are new wireless standards emerging such as Zigbee, Z-wave and EnOcean. Zigbee and Z-wave are mesh networks, meaning that each device can receive and transmit data, and messages are dynamically re-routed from one device to another to get round any interference problems there may be in communicating directly, thereby ensuring a high degree of reliability. EnOcean is a point-to-point RF standard which uses very short signals to avoid interference issues. Its effective range is less than for a mesh network which means more receivers are required, but on the plus side, it can be batteryless, using solar power for some sensor types and 'finger power' for light switches. The energy generated by pushing the switch is sufficient to send the RF signal!

Open systems however, only account for a minor share of the market, and the current reality is that there are dozens of manufacturers producing devices which perform single functions using incompatible protocols (wired and wireless) with very few ways of making them all work well together. It is this lack of standards, particularly regarding communications and interoperability, that is holding back the market growth, since it keeps device prices high, and limits the rate of innovation.

The rise of IP

The rise of IP networking in the home with remote access via broadband cable and ADSL connections is adding a whole new dimension to the open standards debate since there is an emerging requirement for standardisation in the way that remote management software communicates with systems in the home, and the existing 'field network' standards have had to be made compatible with IP. Although the UK lags other European countries in deployment of home automation, we have been leading the conceptual debate in this new area of connectivity standards to the home. This debate is mainly hosted by TAHI (The Application Home Initiative).

What is needed is an open Web Services-based standard which addresses the issues of security and QOS (Quality of Service), so allowing multiple service providers to connect with the home via the broadband Internet link. Examples of these are video on demand, alarm monitoring services, heating system maintenance services, appliance diagnostics, energy usage reporting services etc.

The home hub

The TAHI Open Architecture draft standard identifies clearly the need for a central 'home hub' or residential gateway which is compatible with all the open field network standards and converts the data from various systems and devices in the home to a common format that enables easy management and interoperability between these systems. This needs to be low-cost, easy to install, and maintainable remotely. Use of a central home hub introduces new features such as SMS message alarms and remote control of the house, easy to use graphical pages viewed through a web browser, and logs of temperatures and other parameters so the way the home works can be improved, and energy saved. A good example of a home hub is the Tridium JACE which has already been deployed in many homes in Dubai and elsewhere in Europe, as well as in government-sponsored smart home trials in the UK. The user interface for the JACE is via web pages which can be on a PC or on a touchscreen running in kiosk mode, whereby the browser fills the whole screen.

The low-cost Tridium JACE2 home control hub with direct I/O and multiple comms ports for LON, EIB, Z-wave etc.

The open protocol advantage

The big advantage gained by using open protocols for smart home devices is that one can buy products from a range of manufacturers, so you are not limited to the ideas and style of just one supplier. This is particularly important for lighting control, where the wide range of light switches and other on-the-wall devices available with EIB/KNX gives the homeowner more choice. The other benefit is that competition between manufacturers leads to lower prices, which in turn leads to greater adoption of the technology, which leads to lower prices due to greater volumes, and this virtuous cycle benefits all those involved.

Some powerline LON devices offer even more flexibility, by fitting behind standard switchplates and using the power wiring to eliminate the need for low-voltage cabling completely. Wireless RF devices are now becoming available which also offer this free choice of light switch, and some even work when there is no neutral wire at the switch point, which is otherwise quite an issue if retrofitting such controls.

The selection of 'open' products for smart heating control is more limited than for lighting control, but more are now becoming available from a range of manufacturers. For example, Danfoss uses Z-wave for one of its underfloor heating solutions, but has yet to 'go open' and allow other Z-wave-enabled devices to communicate with its system.

Conclusion

In my view, as of this year, there are now sufficient products available in the UK market at reasonable prices to enable developers to add smart home technology to their larger homes as standard. Even a single home hub control device with appropriate configuration can give many of the benefits associated with much more expensive systems. At the very least, builders should be including low-voltage wiring that will allow the addition of a smart home system at the second fix stage of construction, or post-sale as an optional package. Just as multiroom audio and IP distribution are becoming more mainstream offerings, smart home integrated lighting, security and heating control is now economically viable and desired by many of those purchasing new houses. My advice to developers is to talk to those who are already supplying such solutions to see what is possible - smart homes can be profitable for the builder, and will be valued by the purchaser.

Chris Irwin is the Regional Director of Tridium Europe Ltd.

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