Current wiring techniques for residential homes are not really designed with the smart home and smart lighting in mind. Current smart switches are a compromise to enable them to be easily retro-fitted to existing wiring and to use existing wall switches but, they also have many limitations. If you were to start a new build and describe the lighting user experience required, you would end up with a very different design solution. One that is not limited by existing products on the market. What follows is our ideal design, to deliver the best possible user experience when it comes to smart lighting in the contextual smart home. Whilst it is designed with new builds in mind, it can also be retro-fitted into existing homes and this is how we are undertaking long-term testing in our current home.
We have investigated and researched better ways to wire up a new home with lighting, to provide the best possible user experience and to enable control by any of the many user interfaces used. Our solution is based upon the a simple concept of breaking smart lighting control down into its component parts:
This approach means that light switches can be found where most people would expect them to be and their operation is both simple and intuitive. They also provide high reliability, high performance (very low latency) and a great user experience. If wired with consideration much of your lighting will also work when the mains power supply has failed.
Our proposed lighting architecture for a new build allows us to break the physical link between lighting switches and the lighting fixtures. A standard ring circuit can still be used for power but this has an overlay control bus (IP network), to which all the control elements will be connected.
Whilst it is shown as a ring circuit here, the controllers could all be centralised if required. It is also possible to use a hybrid approach, which combines both rings and clusters of controllers. This is generally easier to implement and also reduces the amount of wiring required.
With this approach, the Home Control System has the ability to monitor state and control every lighting fixture. It models all of the lighting and knows about all of the controllers and switches. Intelligent automation is possible and our preferred approach of a zero-touch user experience should be possible in most cases.
A controller provides a IP network interface and accepts requests to control lights attached to it. One single controller can be responsible for the control of one or many separate lighting fixtures, and this results in a large cost saving over most consumer lighting control systems. The controller can also utilise a single zero-crossing detector for multiple channels. The controller also reports changes in state back to the Home Control System.
In some cases, the controller may also interface directly to switches. This can provide more control options and reduce latency, especially with more advanced lighting such as RGB/RGBW LED strips. It can also provide better resilience and reliability. The controller becomes responsible for reporting switch interactions to the HCS.
The controller may operate 220V ac lighting but it could equally operate 12V dc lighting, or a combination of the two. Some advantages of 12V LED bulbs are that they are much more reliable and much easier to dim smoothly. The controller may also be driving an RGB or RGBW LED strip.
We have assumed wired controllers for best possible reliability, performance and minimal latency but, they could utilise wireless networking technologies such as Wi-Fi, Z-Wave or ZigBee.
When we say 'switches', we mean this in a very loose sense. A switch could be a physical switch, a collection of switches, momentary or latching, touchless or rotary knobs. The key thing is that there is flexibility to install either:
When switches are not directly tied to lighting fixtures, the relationship to lighting is much more configurable and flexible. One switch could be linked to one or more lights or several switches could be linked to one or more lighting fixtures. This allows flexible configuration and groups of lights.
The key benefit of this approach is that you can use any kind of lighting and lighting fixture you want, including halogen bulbs, LED bulbs, dimmable bulbs, LED strips, LED filament bulbs, 12V downlights and even smart bulbs.
With smart bulbs, the controller isn't really doing much but may be included to enable 'switch' control of smart bulbs. It may communicate via the Home Control System, directly with the bulb or with the 'hub' associated with the smart bulbs (e.g. a Philips Hue Hub).
Whilst not shown on the architectural diagram above, it is also possible to power lighting from an additional 12V 'ring' network or by using local transformers. This can provide the additional option of "protected" lighting that continues to work during mains power outages. 12V dc lighting is also much easier to control using PWM techniques, whether it be just dimmable (single colour) or RGB/RGBW lighting.
So what does this mean in terms of wiring up the lighting in a new home?
Our first step would be to change the way the lighting is wired, so that this flexible smart approach can be implemented but, the whole lighting installation can also be reverted back to a 'dumb' configuration if required.
Our approach would be to run 4-core mains cable from each switch wall box to the controller. This gives flexibility and future proofing. In addition, we would installed deep wall boxes (50mm minimum depth).
In addition, we would run an 8-core alarm cable between each switch box and the controller. This enables a wide range of control options when the switch/switches become user interfaces only and are not connected to the mains wiring.
The key thing with this architecture is that the controllers are accessible to allow any reconfiguration. The controllers could be located individually, grouped by room, or simply grouped in convenient locations. They could be even installed in one single location if required. This allows a reasonable compromise to be reached between the amount of wiring used and the length of each wiring run.
This approach also allows the smart elements to be introduced over time and means they do not need to be present on day 1. It also allows flexibility and reconfiguration as the home owner's needs evolve.
Our approach would be to run 4-core mains cable from each lighting fixture to the controller. This gives flexibility and future proofing.
The simplest example using our approach is that the controller is simply a 'junction box' connecting one or more 'dumb' wall switches and there are no 'smart' elements involved.
Whilst we have taken this appraoch to avoid consumer 'smart switch modules' using wireless technologies, the controller in our architecture could be one of these devices if desired. We would not recommned it though. Our approach provides the permanent live and neutral required by a lot of these modules.
