Jonathan Dixon talks about incorporating home automation into a Passivhaus retrofit of a 1960s detached house, built using cross wall construction.
Interview with Jonathan Dixon
Jonathan Dixon is a software engineer with a background in mobile app development, medical imaging and artificial intelligence. He now provides consultancy to others looking to take advantage of home automation.
Learning lessons from different climates
In the mid-2000s, Jonathan lived in a typical South London terrace. The biggest challenge in the UK was keeping the house warm enough in winter while managing the humidity and the potential for damp.
He then moved to California for six years, renting a classic wood-framed Californian bungalow. It had no damp issues, but was draughty. Cold nights would be freezing, and Jonathan also became very aware of the risks of overheating.
Having spent time skiing in the Alps, he also saw that better quality construction was possible. Jonathan didn’t know much about it, but would often joke that his ideal home would be in California, designed by a Swiss person.
Applying software development workflows to construction
Having relocated back to the UK, Jonathan discovered a colleague was working on a Passivhaus retrofit. It was a complex project due to conservation area restrictions. This served as Jonathan’s introduction to EnerPHit and he began to research more about it.
What excited him most was the way the project team worked. Client, architect, contractor and other key trades all used a project tracking app to communicate, manage any changes, and sign off work through sharing photos. Everything in the app then became part of the Passivhaus documentation. The workflows reminded Jonathan of how software development would be managed, and felt like something he could get involved with.
Finding a home with the right build quality was almost impossible
The main criteria for finding the right house was location. Jonathan knew it wouldn’t be possible to buy something that had the level of build quality he wanted, so he expected to do work on whatever he bought.
Original house (south elevation)
Original house (north elevation)
He went in understanding the deep retrofit mentality. If you’re going to do ‘X’ then you might as well do ‘Y’ at the same time. And then you might as well go the whole way and do ‘Z’ too. That meant he was willing to buy something that needed quite a lot of work.
A priority for Jonathan was to install MVHR, as he saw that as an answer to keeping the home warm while managing the humidity.
Home automation wasn’t the driver
Jonathan didn’t buy the property with home automation in mind, but decided to incorporate it while doing everything else. The colleague who showed Jonathan his retrofit project gave him a spare Loxone mini server to play with, and Jonathan spent about a year getting an idea of what he could do with it. The whole house needed rewiring anyway, so he adopted a forward-thinking approach of how to incorporate it.
The Loxone server is like the brains running the house
It’s also very small – about 150mm wide – and could even sit inside a consumer unit. As a programmable logic controller, it monitors what’s happening in the house and executes commands programmed into it. Those commands are whatever you might want them to be, such as changing the temperature or lighting. And it works reliably, without ever going offline to do system updates like a typical computer would do.
For Jonathan, the key to automation is that it’s based on software, so it’s easy to change. You can alter the conditions in the house without having to rewire things, or replumb things. It's as easy as opening a laptop and changing a few bits of programming.
A lot of technology can be connected!
The start of work on the house coincided with the first year of the pandemic, so Jonathan spent a lot of time in lockdown experimenting with the technology. Understanding the mini server was relatively easy, but then it was a case of figuring out the communication protocols that everything else would use to ‘talk’ to each other.
Lights and switches were one thing, but there were also blinds, shading, automated windows, carbon dioxide monitors, and so on. That required a lot of exploring.
In the end, Jonathan stayed within the Blockchain system because it reduced his own learning curve, but he made sure the wiring could be switched to a different protocol in future if needed.
Loxone’s growth provided reassurance
Jonathan felt a natural tension between choosing a proprietary system, where you don’t know if the manufacturer will be around for the long term, and using a combination of different technologies, where compatibility can’t be guaranteed as different components update at different times.
He looked at alternative systems, but went with Loxone because they have invested in their platform and expanded to building control on larger projects. As a result, Jonathan is happier that his system is much more robust now.
The house’s cross wall construction presented an opportunity
In the 1960s, cross wall construction was an experimental build-type. It means the two gable walls are loadbearing, while the front and rear walls are non-structural ‘infill’ curtain walls.
Jonathan spoke to nine different architectural practices, looking for local knowledge and Passivhaus expertise, but none really picked up on the construction method. Just as he was about to appoint someone, he came across A D Practice. The cross wall construction, and the retrofit potential it offered, was the first thing they noticed.
The non-structural walls could be demolished and rebuilt to a much higher standard, rather than trying to insulate them and get all the junction detailing right.
‘Buy in' was essential for all team members
Because EnerPHit projects are relatively rare, it’s hard to find people with relevant experience. Jonathan’s main requirement was that the architect and contractor be serious about Passivhaus being part of their future. As a beginner himself, he didn’t want to pull people along on his own journey.
The foundations had to be dug twice
Building Control changed their minds and were unwilling to sign off the original floor design, despite the ground being fine. Rather than backfilling what had been dug out, they decided to double the amount of insulation in the extension floor. It cost the same as backfilling and turned this frustrating situation into a positive.
A software development mindset was beneficial
Jonathan was very open to change as the project progressed. He puts this down to the iterative development process, and looking for opportunities for improvement. You can’t design something and expect it to turn out perfectly as conceived.
Caring about the construction, especially the invisible elements, also played a part. Knowing that the airtightness couldn’t be compromised, that the right levels of insulation were important, and so on, meant caring about the process as much as the end result.
Help with the lighting design paid dividends
Jonathan began to put in the automation infrastructure, and was varying it as he went along. But he realised trying to ‘wing it’ was only getting him so far, as he hadn’t thought much about what lighting would actually work with the automation.
At the same time, he avoided going over the top with settings. With the Loxone system you could effectively have disco lighting if you wanted! Whereas the real benefit is in settings like night lighting. For example, if you have a guest staying, you can program low level lighting to help them find the bathroom easily during the night.
Energy management is possible with home automation
However, Jonathan thinks the real gains would be seen across an estate of many properties. He has experimented with things like running the heat pump according to times of high solar production, and he has other ideas, but in a single home the savings are marginal.
Home automation helps to balance different Passivhaus features
In a typical house, you have the heating on until it is warm enough, turn it off, and then turn it on again when it gets cold. In a Passivhaus, you have multiple things that could end up working in conflict, and which need balancing: winter heating, summer shading to guard against overheating, MVHR bypass, and so on.
Multiple systems running together can be inconvenient, and even waste energy. Integrating them all through automation means they all just do what they need and work towards a single goal.
There’s not much point trying to manage the temperature in individual rooms, because Passivhaus delivers such stable temperatures. But Jonathan found that a room used occasionally as a guest room could be too warm, so he had to invent a way to allow guests to set a slightly cooler temperature when needed. That was the only zoning he incorporated.
Simply logging and monitoring data can be helpful
Through his consultancy work, Jonathan has actually convinced several friends to build to Passivhaus standard where they weren’t originally planning to do so!
For other properties, data logging and monitoring helps to identify particular things causing energy bills to be high. It can go to the level of monitoring individual circuits and seeing where energy is going. With the data gathered, you can then use automation to manage different areas of the house, keeping some cooler when they’re not being used. Motion sensors or predictive models can provide heating when it’s needed.
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