Heat Exchange in Commercial Kitchens: Energy Efficiency & Cost Savings

According to the Swedish Energy Agency, Sweden’s municipalities could save nearly €60,000 daily if they improved the efficiency of their commercial kitchens. Ventilation makes up a big part of a commercial kitchen’s energy use and while it can be reduced through heat recovery from extract air, implementing a heat exchange system in a tough environment where there are large amounts of grease, soot, and smoke and doing so in a cost-efficient way has proven challenging – until now: Swedish Greentech company Enjay has developed a heavy-duty heat exchanger that is designed to withstand the toughest environments, recovering the energy from exhaust air in kitchen ventilation system and returning the energy to the building for multiple usages and with significant cost savings. Or, as Enjay CEO Jesper Wirén says:

“Today, the inherent energy in kitchen exhaust ventilation is considered waste – our technology turns that waste into a new, renewable heat source for your building, saving up to 90% of your restaurant’s ventilation heating costs.”

Wirén continues, “Heavy duty environments need heavy duty solutions. Your standard heat exchange system is not going to cut it in a harsh commercial kitchen or laundry – you need something as tough as your environment.”

Back in the 1990s, Enjay co-founders Jesper Wirén and Nils Lekeberg formed UVtech, which developed a ventilation purification system specifically for commercial kitchens using UV filters. This solution is now more or less standard in most commercial kitchen hoods. In 2006, the two men had sold the company and moved on to other ventures, but despite that, customers kept contacting Wirén and Lekeberg, asking if the filter they had developed could be used to protect traditional heat exchanges.

“Everyone we met said the same thing: we know we waste all this energy into the ambient air because grease is clogging up the technical equipment – can we use your filter to protect traditional heat exchanges?’” explains Jesper Wirén, Co-founder & CEO, Enjay. “We had to tell all those customers ‘No’, since our testing had shown that UV filters – or any filter for that matter – will not remove enough of the grease to keep the heat exchangers clean and enable robust and profitableenergy recovery.”

“Nils and I have been working with restaurant ventilation for 30 years, so we decided it was time to crack this problem,” says Wirén. “To make a long story, where we spent many days in front of a barbecue in a test-rig, short; one day we had a eureka-moment”

”We realized that all the existing standard heat exchangers in the market, had a built-in major problem with polluted air: to optimize energy recovery in general ventilation, standard heat exchangers all utilize the Coanda effect to make sure the air flow streaks towards the energy transferring surfaces. Unfortunately, that means that all pollutants also flow towards those surfaces. This creates a massive problem since, unlike the air, the pollutants tend to get stuck to the surface, and if there is one thing that is catastrophic to a heat exchanger, it is to get a build-up of a coating on the energy transferring surfaces. Our Heureka-moment was that we realized that standard heat exchangers work against the natural forces, and during the test period, we had discovered how to avoid this.”

The Lepido heat exchange system works with the natural forces, thanks to its’ unique internal Particle Repellent Geometry, PRG. Lepido is based on several patent families that allow the heavy-duty recovery battery to recycle energy in challenging environments. The patented solutions keep the coils of the recovery battery operational, minimizing the need for maintenance.

“The one thing we realized was that this was not just a sustainability solution, it was also a money saving solution,” says Wirén. “Most companies do well in their environmental work and they’re positive about it, but the tipping point is money. And for sustainability managers the Lepido system is a weapon they can take to their managers and say this will save you money and at the same time we can show very good figures around what we’re doing to protect the environment.

Proof of concept

Enjay built its first prototype in an old school in the south of Sweden. Once they had proof of concept in that environment, they knew they had to test it in ‘real’ conditions.

“We said that if we’re going to do this, we need to make sure that we can take on all restaurants,” says Wirén. “The worst possible case is a Burger King, because it’s a lot of heat, a lot of grease, and a lot of soot. The combination of the three creates something that looks like tarmac and it destroys everything in its way within six weeks. So, we said let’s go after that because if we’re successful in a Burger King, we can do any restaurant.”

The problem was finding a Burger King that would let them test in their restaurant. 99% of all Burger Kings are franchises and the buildings they occupy are owned by the parent company RBI, so not many franchisees are willing to put their own money into an as-yet unproven technology.

“We finally found a franchisee in Malmö and nagged him until he agreed to let us try it. We told him we won’t disturb you – we just want to try it out. If it doesn’t work, we’ll put everything back the way we found it – and if it works, you get to keep it for free. We made him an offer he couldn’t refuse and eventually he said yes,” laughs Wirén.

“This gave us the proof of concept not just for the technology – we were also able to show the commercial proof of concept, because the customer actually saved more money than expected,” says Wirén. “We had calculated a bit low in order to not over promise, and they were so happy with the results they ordered three more units. Then the franchise master took notice, because a franchisee will rarely spend money unless they are forced to, so the franchise master was very curious as to what was going on.”

Once the franchise master understood what was happening Burger King’s parent company started taking a closer look, first doing a technical checkup, then a visual look at the system. They monitored it over the course of several years and eventually decided they would include the Lepido system in all newly built Burgers King restaurants in Scandinavia.

“In Sweden we have really green energy, so you take the amount of energy you save against the equivalent, but this is different in every country. So, in Sweden it’s 0.05, whereas in Poland, where you have a lot of coal, it is 0.5. In real terms this means in Sweden one restaurant saves about 4 tons of fossil fuel C02 per year. The same restaurant in Poland would save 40 tons,” says Wirén.

How IoT fits in

Connecting the Lepido system with IoT devices allows Enjay to not just promise their customers savings but show them.  With the data generated, Enjay can show hard numbers on how much is saved on a day, over the last month, or compared to January last year.

“Theoretically, you can also store the energy,” says Wirén. “One of our solutions is with a heat pump – you can store that energy in a tank. This is also where IoT is important, because we want to build an AI system around that. We’re starting to face a time where we’ll be charged by maximum power consumption in a given time period. AI can read when the peaks are each day, so we could help customers to ‘cut’ the peaks and by doing that lower their energy costs even further.”

Enjay is also moving from products to services.  While Burger King is installing the Lepido system in all newly built Burger Kings in Scandinavia, it’s also looking at retrofitting existing restaurants, where Enjay will own the units and charge for the service.

Says Wirén, “In the words of Burger King Scandinavia: ‘For new-builds, it’s a no-brainer’, since the alternative cost to include Lepido when they build a new site is generally less than $15 000, which translates into very fast return on investment. However, when we started looking at retrofitting existing Burger King restaurants, we realized that the cost of installation is often double that for the new builds. Also, when the franchisee has a new build, they get all the costs included in the rent. With a retrofit they have to find that money themselves, so they might need to find 30-40 thousand dollars to do the installation.”

Enjay started looking at how to finance the retrofits for the restaurants that wanted and needed them. Today, they offer a twelve-year contract with no initial investment, so the franchisee doesn’t need to find that big chunk of money in order to experience the benefits of the Lepido solution.  The units are connected with IoT-enabled devices, allowing Enjay to monitor the system, and if something goes wrong, an early warning is sent, and they are able to address any challenges quickly.

Enjay measures things like the pressure drop and the energy for the customer, while also enabling more than 50 other data points so that in the future they can offer the customer additional products, much like Tesla is doing.

“Technology is evolving, and customer’s needs are also evolving, so we’re preparing for what will be needed tomorrow, not just today,” says Wirén. “Of course, job one is making sure the system is working, so while we are futureproofing, we are also staying on top of the customer’s current needs.

“There is a lot of potential of what we can do with an IoT solution and how beautiful that can be. IoT creates business opportunities for us but it also creates benefits for the customer in a number of different ways, including peace of mind, because they can quantify the energy savings in kWhs and subsequently translate that into other savings, like fossil CO₂equivalents – perfect functionality to meet for instance the new EU Taxonomy regulatory requirements on sustainability. We can generate reports through Tele2 IoT’s connectivity management system 2CONTROL, which allows them to prove compliance. This is a big thing, because they face fines if they don’t meet certain requirements.”

The future

The Lepido system is launched for commercial kitchens – fast food, hotels, shopping malls, hospitals, schools, even maritime sights such as ships – where there is a need for energy and where they already have a lot of energy that can be utilized. But there are still a lot of heavy-duty areas where heat recovery is challenging and where a system is needed.

“We’re looking at and adding new segments. We’re starting with laundries, where lint is a big problem in ventilation,” says Wirén.  “We’re in the R&D stage with a French company – seeing what happens when lint comes in and understanding how we need to adjust things to handle these new conditions – and it will be at least 18 months before it is introduced to the market. Basically, we’re working segment by segment and perfecting the technology for each one before moving on to the next.”

While laundries may be the next segment for Enjay, they are turning over every rock to see where their solution can be beneficial and where there is a lot of value from saving energy, hitting sustainability targets, and also saving money.

“Energy prices are going up everywhere, so people are looking for new and innovative ways to not just save energy, but to also reuse it and save money,” says Jesper Wirén. “We have companies from a lot of different industries reaching out to us within the Nordics, but also into Europe and beyond. The problem is global and the solution doesn’t depend on which country you’re in – it works everywhere, no matter what.”

Enjay is also teaming up with different players in the energy sector who know where the problems exist.

“We are working in very specialized areas, so partnering and forming ecosystems enable us to address problems and challenges successfully because we’re all bringing different knowledge to the table. When it comes to the IoT part of things, we can share data and look deeper into things, which is much more efficient and helps everyone as we move forward with solutions.”

If you would like to learn more about how IoT can enable your business, please get in touch.