Spotlight on: Johan du Plessis, founder and chief executive, tepeo

Johan du Plessis

Andrew Gaved hears from Johan du Plessis what makes the Zero Emission Boiler (ZEB) a key element in the low carbon heating landscape.

In the recent Sustainable Energy Association report on a technology-agnostic approach to heating and buildings, it was noted that a tendency to believe that heat pumps were the only solution for all buildings was becoming a barrier to low carbon progress.

One of the most forthright and passionate voices in the debate that followed was Johan du Plessis, founder & chief executive of tepeo. Hardly surprising perhaps, given that tepeo’s ZEB (Zero Emission Boiler) technology is one of those alternatives left out in the cold by the government when handing out incentives for low carbon heating.

This makes it a playing field that is distinctly unlevel for anyone developing any low carbon technology that isn’t a heat pump. For Johan, who has in the ZEB, which is technically classified as a heat battery, a product that offers compelling benefits to the occupants of average-sized houses, it is clearly a source of much frustration.

But first, we need to clear something up. Despite the fact that heat pumps have been grabbing all the headlines and the available cash, he is not a heat pump hater. In fact, he is a big fan of the technology: “People often think that I don’t mean that, but I really do,” he says, “But I just think that going about saying that heat pumps are perfect and solve the problem for everyone doesn’t build trust because it’s not true. They’re not perfect.”

He thinks that starting from such a purist standpoint doesn’t help the cause of heat pumps, and hands too much ammunition to the opposers of electrification. “Often this industry focuses too much on the theoretical,” he says, “The theoretical says yes, a heat pump can probably solve the heating problem for every building. But the longer we keep going around saying that they’re perfect for every home, the more we are actually just creating material for the gas lobby to push the other way and highlight Mr and Mrs Smith’s terrible experience with their heat pump installation.”

But in his view, there are two ways to approach electrification, each of which is equally valid: “The technology has to either focus on massively increasing the efficiency of the use of energy, which is what a heat pump does – or it has to give you massive benefits in terms of the flexibility…The UK spends a couple of billion pounds a year curtailing wind and calling up flexibility to manage the network. So, these are costs which if we had more flexibility embedded in our homes, we can definitely mitigate a lot of.”

But of course, it is the sheer amount of cash the government is putting towards heat pumps that is a major irritant for the manufacturers of alternatives. “The government keeps talking about a technology agnostic approach and yet heat pump gets over£10,000-worth of support if you factor in the VAT relief and the Boiler Upgrade Scheme subsidy of £7500,” says Johan, “We have to apply VAT or the installer has to apply it and there’s no subsidy. And that is making it very difficult.”

The ZEB’s origins

The ZEB’s origin story can be traced to Johan working with OVO Energy on the integration of a new acquisition called V Charge and its concept of the Virtual Power Plant back in 2016. “The fundamental question was: how the hell do you manage a highly renewable electricity grid and you have to match generation supply and demand at all times of the day, across the year, but you don’t have control about when that energy is available? The only way you can change this without getting customers to change the way they use their energy is through flexibility – you have to have flexibility in your system somewhere to store that energy.”

Although originally focused on Electric Vehicles, it soon became clear that at that time there wasn’t enough of a physical estate to build on in EVs. So, attention turned to an oft-maligned technology: storage heaters.

“We have 6 million storage heaters installed in the UK,” says Johan, “The concept of storage heating is not a bad one. It’s the execution. They are actually very high-density energy stores, but they were developed in the Sixties, by the Electricity Boards to get rid of nighttime nuclear energy and they were designed with that perspective, rather than through the lens of ‘how do we actually make a warm, comfortable customer experience?’”

What V-Charge did was to attach an electronic control box onto storage heaters in a range of homes and social housing projects across the country – charging it flexibly, in order to use the electricity when it was cheap at night. “We were aggregating all of these assets into a large demand-side response asset – basically a very large distributed flexible battery.”

That led to him thinking, what if he could come up with a central heating version of a storage heater, using a heat storage core, but bringing in customer-friendly features and offering flexibility and control? “We could support the electricity grid and start to solve that problem of needing more renewables, while creating a really good customer experience,” he says.

To really make the ZEB work to the benefit of customers and the industry alike, it needs a couple more policy levers to be pulled, Johan stresses. Firstly there is SAP, the Standard Assessment Procedure, the regulation that sits behind EPCs, which as currently configured treats the home as an island, rather than part of the energy infrastructure and so doesn’t value flexibility and the benefits it brings to the home and energy system alike.

“The government is now trying to address this through its Home Energy Model (HEM), which they are currently consulting on,” he says, “But we have some serious concerns about how it’s going to be implemented and if in fact it is going to be implemented at all.”

The other key area is around the electricity market itself, in particular REMA, the review of electricity market arrangements, he says: “We need to remove the discrepancies between gas and electricity prices, which is only going to grow over the coming years…Fundamentally to have a more technology agnostic approach, you need to allow industry to come up with innovations that give customers the best experience – but the market won’t develop if  the cost of using those products is artificially high – if market signals aren’t aligned to what we’re trying to achieve. At the moment they’re not.”

The ZEB in detail

I ask Johan for the elevator pitch for the ZEB: “It is a simple plug and play replacement for a fossil fuel boiler. You can think of it as a smart heat battery. What we are doing is taking electricity from the grid when it’s cheap and low-carbon and we are then storing that energy to put that into the home whenever your thermostat asks for heat to go into your radiators or your underfloor heating.”

With the ZEB, granular data is key to the customer experience – it uses machine learning to build up a model of when heating will be needed over the next day or two and it then optimises when to charge the heat battery based on the homeowner’s particular preferences. “You need to be on a flexible tariff, that gives you some variability in the price of electricity. The ZEB will change at the optimal times using price and the carbon intensity of the electricity network in your area and based on how carbon- or cost-conscious you want to be,” Johan says, “The key is that by buying electricity flexibly, we can actually get the cost of running the ZEB right down to close to parity with a gas boiler. It is generally going to be about 10-20% more expensive in practice, but it is going to significantly reduce your carbon footprint and it’s going to allow you to do that in a way which is less intrusive in your home and also easier to understand than a heat pump.”

Johan says that on average within about two or three days it will become very good at knowing when you use your heating: “We have second-by-second data that we get back. It’s aggregated so we can also look at a longer timeframe. And so what that means is that we typically will know if there’s a problem with the heating system before the customer does. As time goes on, we will be able to do more things like predictive maintenance and we can potentially help people to improve the efficiency of their heating system by giving them some tips and suggested changes.”

The ZEB model which is currently available is the ZEB-40R, standing for a 40kWh usable storage capacity. It has a rated power output of 15kW thermal and power input of up to 9kW electrical. “We typically advertise that it’s suitable for up to the median UK home by heat demand, which is about 12,000 kWh a year, so it is definitely a solution for smaller to medium-sized homes,” Johan says, “The problem you have with larger homes is that you can’t get enough electricity into the home flexibly enough to get the running costs down. And so for those homes, you really do need a heat pump solution, even if it’s a hybrid solution where a heat pump plays a part of it to bring the overall volume down.”

There is also a potential route into social housing, provided some of the barriers around SAPS and EPCs can be overcome, he adds. “We get approached by loads of social housing organisations that want to do this. And this is ideally suited for some smaller social housing properties.”

This is the third iteration of the ZEB, which Johan notes looks outwardly very similar to the previous iterations, but under the hood it is much more advanced. tepeo is going to be launching a smart diverter solution by the middle of the year and a combi solution by the end of the year – though Johan won’t say too much about it yet: “We are thinking just a little bit about how we talk about it, because we don’t want people to imagine a combi gas boiler – you’re going to need space for something of washing-machine-size, as you can’t solve the instantaneous hot water solution without having thermal storage or energy storage. So to include that storage, it is going to need to be a bigger solution physically than a combi – there’s no point getting people excited about an impossible solution that turns physics on its head.”

The population of ZEBs is currently in the hundreds at the moment and they need to be in the thousands in the next year or so, Johan says. He also has ambitions to create both bigger and smaller versions over time and other developments underway include hybrid solutions and options for commercial buildings – although Johan notes that one of the barriers to that is just that there are fewer available flexible tariffs than in the domestic space.

Retrofit potential

But, along with offering a customer experience that has the familiarity of a boiler, the ZEB offers another key benefit, and arguably an advantage over those heat pumps – it is ideal for retrofit applications: “We are really suited to retrofit,” stresses Johan, “That’s not to say we are not interested in newbuilds, but if you think about the pain points from customer pain points, there’s no customer in a new build to be bothered about the upheaval. You’re not changing out radiators, you’re building it from scratch. So the cost of installing a heat pump in a new build is much lower and easier to manage. So we’re less competitive against the alternatives. I think as a society we should be forcing house builders to be putting in heat pumps.”

The real challenge, however, is in the scale required to decarbonise heat: “We have got 26 years to decarbonise 26-27 million homes, and yet we are building only 200-300,000 new homes a year. It’s a tiny market. That’s not to say we shouldn’t be building newbuilds better than we are. Hopefully the Future Homes Standard, which is now being consulted on, will help make some of the changes that should have happened years ago. But a Retrofit Home Standard would be good too, wouldn’t it?”

Role of the installer

There is one further element in the tepeo plan to take on retrofit and that is installation – because of course, like any heating technology, the ZEB will only deliver all its benefits if it is correctly installed and maintained.

Here again, the connected nature of the ZEB promises a better customer experience, Johan says: “With a conventional gas boiler, if there’s a problem, the response is ‘Okay, fine, we’ll send someone out next week to have a look.’ But when the installer comes out and works out what the problem is, it is quite likely they haven’t got the appropriate parts with them. The great thing with the ZEB is things will go wrong, but we can see there’s a problem or even that there’s going to be a problem. We don’t need to send someone out to investigate because we actually know what the problem is already, but we can send someone out with the right parts. And so that reduces the number of visits and ultimately reduces the cost of maintenance, and customers get that confidence that someone out there is actually looking after the product…And in most cases with a gas boiler, while the installer might have a direct relationship with the customer, the manufacturer doesn’t. That’s how we are being disruptive.”

The company is currently building the tepeoPRO network to build this relationship, with 70 different installation businesses currently signed up and the ambition to grow significantly in the next year:

“We don’t employ them directly, they run their own businesses, but what we are giving those installers is an alternative product which they can offer their customers, which is low carbon and is really easier for them to transition to. And it makes best use of all of the skills and experience that they’ve got because it’s so similar to installing a gas boiler, minus the gas.”

For Johan, these installers have a combination of skills which are too often overlooked: “If you think of our business, we’ve got engineers, we’ve got marketing, we’ve got sales, we’ve got aftercare, and we’ve got operations and finance. An installer has to be all of those in one person…There are some brilliant installers out there who do embody all of those aspects. I guess we want to help installers to be better for their customers and to be able to provide them that better service. I think it’s something which the gas boiler industry has maybe not done particularly well. So we want to try and do it better.”

The electrification of heat will be one of the key topics at the InstallerSHOW on 25th-27th June. Register for FREE tickets here: