Technical Director Darren Yearsley on: Net Zero

“You have to make sustainable technologies a no-brainer.”


“So much of the environmental and decarbonisation space is filled with messages like ‘you should’, but willpower can only take you so far. If you want to drive real change, you have to find ways to make the right thing to do the path of least resistance.”

Waterware Technical Director, Darren Yearsley, is passionate about business optimisation and full-service solutions, both of which Waterware is delivering to the New Zealand building industry. “Historically, we have been known as a specialist in radiant heating systems and commercial hot water systems but, over the years, we’ve transitioned from being a product supplier into being a solutions provider. We now have a pretty broad portfolio of products which allows us to create integrated systems and provide wraparound support. We really understand the products we’re selling and we’ve developed a lot of skill in how to combine them intelligently.” One of the ways Waterware does this is by combining radiant heating systems with high-capacity hot water systems, he says. “A package like that might have 40 or 50 components in it and by getting the complete system through us, we’re able to help with commissioning and downstream trouble-shooting as well.”

The Waterware team is also working hard to keep up with the changing needs of our built environments, and to create better efficiencies and outcomes for their customers. “Most people are familiar with the traditional split system used by an air-to-air heat pump. Our air-to-water heat pumps use a similar outdoor system but can create hot or cold water instead of air, which is then used to create a radiant heating or cooling effect, and to supply hot water cylinders.”

Darren and the team looked overseas for inspiration on how to make the most effective radiant cooling systems after realising that the limiting factor in slab-based cooling systems was condensation. “Underfloor cooling can reduce the ambient temperature in a space by 3-4 degrees, but if you push it any further than that you’ll start to affect the comfort of walking on the floor. We learned that in some parts of the world they were using ceiling-based systems instead. This uses a panel behind the plasterboard which turns the ceiling into a radiant surface that is light, easier to cool and, because you’re not in contact with the interior ceiling, you can deliver more cooling power with affecting comfort. With that system, we’re now able to double that cooling potential to 7-8 degrees, all while avoiding condensation on the surface.”

Waterware has pioneered this technology in New Zealand and the response from their high-end residential market has been extremely positive, Darren says. “The outcome for specifiers is one appliance to produce hot water year round while also producing seasonal radiant heating and cooling. The running costs are about 25% lower than an air-based system. It’s totally silent and persistent with no air movement, so you’re not kicking up dust, and you can have the doors and windows open and still achieve that cooling effect.”

As the market has begun to lean more strongly toward renewables in the last 5-10 years, Darren says that Waterware has really grown into that space as well, in particular with their Net Zero water production system for multi-unit residential properties. “For an apartment building, for instance, you’ll have a peak period of water production from, say, 7am to 9am, and then a smaller peak again from 6pm to 8pm. That need dives much lower in the middle of the day when buildings are empty, which opens up a really nice window where you have the opportunity to recover the hot water system while the sun is shining in the afternoon.”

The low-cost, centralised Net Zero water system offers large on-site water storage which, when engineered correctly, can have all the hot water already stored for that first peak delivery, recover via a solar PV system in the afternoon sun, and then deliver the smaller evening peak with reserves to spare for the following morning. “Net Zero is an engineering modelling tool that puts key metrics together to help specify hot water systems with exactly the right components in exactly the right proportions. When you get that ratio of hot water storage to recovery to solar PV right, the capital cost of a Net Zero system in a multi-unit residence is on par with an electric hot water system with the same number of individual units – once you tip over about 40 units – and the ongoing running costs are considerably lower. Yes, Net Zero is helping to decarbonise the environment and enabling the industry to do less with more, but that is really because the numbers are so compelling that it’s an obvious choice. That’s how you change the market, by making sustainable technologies no-brainers.” Darren says that there is an overwhelming need for this more holistic approach to the market, which Waterware is delivering with end-to-end solutions that cover hot water production, control valves for distribution and wireless metering systems for tracking.

Waterware’s busy young team of 40 has also been working hard to support the industry with systems which offset some of the most critical pandemic challenges. “We are always looking for opportunities to create value through innovation across the business, not just through products. Most recently, we’ve developed a service called Smart Cart which directly addresses some of the supply disruption we’ve seen across the industry. Rather than stockpiling materials for a project all at once – some of which you might not need for 2 years – Smart Cart gives you a login where users can go into their portal, view all of the quotes we’ve done for them and then accept jobs they’ve won in parts. This enables them to lock in prices, stagger delivery of the materials and then we schedule everything on the back end. This transparency guarantees both price and product delivery while addressing some of the major supply issues we’ve seen in the last few years in a really cost-effective way.”

Over the next few years, Darren says Waterware will be focusing strongly on the implementation of some great ideas the team is already working on, as well as doing more to bring their story to the fore. “We’ve driven a lot of change in the last 2 or 3 years and now it’s time to tell those stories to the industry. Net Zero is really game-changing in its ability to provide theoretical models of how the system will work. Not only can it provide accurate running cost analyses for commercial builders, it can also provide carbon emissions analyses to institutional organisations who are serious about carbon reduction so they can see how they’re tracking down to the kilogram. We have no shortage of great ideas; implementing them is where the hard graft comes in. Our job now is to spotlight these solutions we’ve been working so hard on and really show our vision to the industry.”

To learn more and connect with Darren, visit