New EU Rules on Greenwashing: How We at Hetki Look at Sustainability in Finnish Outdoor Saunas

Sustainability has become part of the language of business and marketing. Terms such as green, eco-friendly, responsible, energy efficient and carbon neutral are everywhere. Sometimes it's difficult to know what any of them actually mean. That's becoming more than a question of language.

New EU rules aimed at protecting consumers from misleading environmental claims are changing how companies can communicate about the environmental performance of their products. The rules are part of Directive (EU) 2024/825, commonly known as the Empowering Consumers for the Green Transition Directive. From 27 September 2026, Member States are required to apply the national rules implementing the Directive.

We don't have sustainability fully figured out at Hetki. We manufacture a physical product from wood, glass, steel, insulation and other materials. We use energy to make it, and because our saunas are delivered fully assembled, transporting them to customers can involve long distances. Every sauna also has an environmental impact throughout its working life.

That reality is where I believe any honest discussion about sustainability should start.

What do the new EU rules on greenwashing mean?

The basic principle behind the new rules is relatively easy to understand: environmental claims should mean something.

Among other things, the new rules restrict broad environmental claims such as green, eco-friendly or energy efficient when the required basis for making them can't be demonstrated. They also restrict sustainability labels that aren't based on a certification scheme or established by a public authority. A company can't present an entire product or business as environmentally preferable when the claim actually concerns only one particular aspect of it. Certain carbon-neutral or similar product claims based on offsetting are also prohibited.

For companies, this means being much more precise about what they say. Instead of simply describing a product as sustainable, green or energy efficient, they need to consider exactly what the statement refers to and what supports it. For consumers, the change should make environmental information easier to understand and evaluate, and make it harder for a broad environmental message to hide a much narrower reality.

The rules are relevant to Hetki because the materials we use, the way our saunas are constructed, the energy they require and the distances they travel all matter. So when we talk about any of these things, we should be clear about what we know and what our statements are based on.

It's the same principle we try to follow when talking about sauna, health and wellbeing. Research into sauna and health is interesting and important, but an association found in a study isn't automatically a promise about what a particular sauna will do for an individual person. Environmental claims deserve the same care.

Sustainability and Finnish sauna: let's start with the impact

There is no impact-free outdoor sauna. Wood has to be harvested and processed. Glass, steel and insulation have to be manufactured. Components have to be transported, the sauna has to be built, and the finished product has to reach its customer. Once there, heating the sauna continues to have an environmental impact, through the electricity it consumes or, in a wood-heated sauna, the emissions from burning wood.

What matters, then, are the individual choices behind the product. Instead of putting one broad label on the finished sauna, we think it's more useful to look at how it's designed, what it's made from, how it's constructed and how long it's intended to remain in use.

Some of those choices involve trade-offs. A robust construction can require more material. Large windows have an environmental footprint, even though they can be an important part of the experience and design. Insulation is another material that has to be manufactured, yet it also has an important function during the many years in which a sauna is heated. Sustainability isn't particularly useful as a simple yes-or-no description of a product this complex.

Sauna sustainability starts with longevity

If we're going to make a physical product, we want to craft it for a long life. This is perhaps the most fundamental principle behind the way we build Hetki saunas.

Our ambition is that a Hetki sauna can serve its owners for decades and perhaps, one day, from one generation to the next. We deliberately say ambition, because Hetki hasn't existed for generations and we can't yet prove that our saunas will. What we can explain is how we build them with that objective in mind.

The walls of our saunas are made from 88 mm (3.5 in) laminated Finnish spruce logs. We use robust materials and construction methods, and our choices aren't based on making the lightest or thinnest structure possible. Quality, durability and design are closely connected in the way we think about the product. We want the sauna to remain safe to use, work well, look good and bring joy and wellbeing for a very long time.

Longevity alone doesn't make a product sustainable. It's one part of a much larger picture. But we believe that how long a product is intended to remain useful is a question worth asking when considering its impact.

Energy use and the construction of an outdoor sauna

A sauna is deliberately heated to a high temperature, so the way it's constructed matters. Rather than describing a Hetki sauna simply as energy efficient, we prefer to explain the construction and let the facts speak for themselves.

The roof is insulated, which is particularly important in a sauna because hot air rises and the temperature difference between the sauna and the outside can be considerable. Our thick log walls also play an important role in the thermal performance of the sauna, particularly compared with lighter, uninsulated structures. Our windows use double-pane, argon-filled glazing with two 6 mm (0.24 in) glass panes. We also pay attention to the construction of the exterior door, where insulation and glazing choices matter. Together, these choices help limit unnecessary heat loss when the sauna is heated.

How often the sauna is heated, for how long, the heater used and the source of the energy all matter during its working life. Our own carbon footprint assessment reinforced the importance of looking beyond manufacturing when thinking about the environmental impact of a heated building.

Finnish wood, traceability and certification

Timber has a long history as a building material for Finnish outdoor saunas, and log saunas remain an important part of that tradition today. At Hetki, we continue that tradition with spruce logs. Knowing where this key raw material comes from gives us and our customers something concrete to evaluate.

Independent certification can provide another layer of information. The producer of our log material operates a PEFC-certified chain-of-custody system, and the manufacture and factory production control of the laminated logs are covered by third-party product certification.

That concerns a particular material, process or part of the supply chain. We shouldn't turn it into an environmental claim about the whole sauna. That's exactly the kind of shortcut we want to avoid. We'd rather be precise about what it covers.

Why doesn't Hetki have an environmental certification for the whole sauna?

It's a fair question. If these issues matter to us, why doesn't the complete Hetki sauna carry an independent environmental label?

Third-party certification can be valuable. It gives customers criteria and external verification rather than asking them simply to accept what a manufacturer says about itself. For a small company like Hetki, however, finding the relevant schemes, collecting the required information, going through the process and maintaining it can require considerable time, expertise and financial resources. With limited resources, we've had to make choices about where to focus them.

This doesn't reduce the value of independent verification or give us a reason to replace it with unsupported environmental claims of our own. So far, we've focused much of our available resources on things we can directly influence in the product: how our saunas are designed, what they're made from, how they're built and how long we intend them to remain in use.

We don't consider this work finished. Better environmental data, relevant independent certification and greater understanding of our impact are all areas in which we want to continue developing as Hetki grows.

What our sauna carbon footprint assessment tells us, and what it doesn't

In 2024, we wanted to understand the carbon footprint of our saunas better. As part of a university of applied sciences thesis, a carbon footprint assessment was carried out for the Hetki collection. The work used One Click LCA and the Finnish Ministry of the Environment's low-carbon assessment methodology available at the time.

The study was useful. It helped us see more clearly where emissions associated with our materials and manufacturing come from. It also highlighted one important characteristic of building with wood: the timber used in the sauna stores biogenic carbon that the trees absorbed from the atmosphere while growing.

This is particularly relevant to the way we build. A Hetki sauna is a substantial log structure rather than a lightweight timber frame, so a considerable amount of wood becomes part of the structure. And because we design our saunas with the ambition that they will remain in use for decades, our aim is for that carbon to remain stored in the structure for a long time.

But there are important limitations, and leaving them out would give a very different impression of the study. The assessment wasn't a complete life-cycle assessment of a Hetki sauna. It covered the product and construction stages included in the study, while the use phase and end-of-life stages were excluded. Final transportation of the completed sauna to the customer was also excluded, even though our saunas can travel considerable distances. Some components weren't included, and the report itself discusses uncertainties in the available emissions data and methodology.

For those reasons, we don't use the study to claim that a Hetki sauna is carbon neutral or carbon negative. It doesn't establish that. Its value is in helping us understand our product and its environmental impact better.

Why sustainability questions matter when buying an outdoor sauna

One thing has surprised me during the years we've been selling saunas: customers rarely ask us about sustainability.

They ask about the heater, size, benches, windows, delivery, design and, naturally, price. Those are all important questions. But questions about where materials come from, how the sauna is constructed, how long it is intended to last, how energy use has been considered or what environmental claims are actually based on are still relatively rare.

I wish they weren't. More demanding questions from customers would probably reveal things we need to improve, and that's exactly why those questions matter. When customers ask better questions, manufacturers have to provide better answers. That can push us at Hetki to learn, measure and improve, and if enough customers start asking those questions, it can help move the whole outdoor sauna industry forward.

Respect also means being open about what we don't know

One of our values at Hetki is Respect. It means respect for our customers and partners, for the people who make our saunas, for Finnish sauna culture and for the environment and resources we depend on.

Respect doesn't mean claiming perfection. We're a small company and still relatively early in our journey. There are things we know, things we're working to understand better and things we know we need to improve. New materials, better data, new manufacturing methods and more appropriate certification may give us opportunities to make better choices in the future.

I believe trust isn't built by finding the biggest possible words for what you're already doing. It's built over time through what you actually do and by being willing to explain it.

What should you ask when buying an outdoor sauna?

If you're considering buying an outdoor sauna, don't stop at words such as sustainable, green or eco-friendly. Ask what they actually mean in relation to the sauna you're considering.

Ask where the wood comes from and what the sauna is built from. Look at the construction, wall thickness, roof insulation, windows, doors and heater. Ask what an environmental claim, if any, is based on and what any certification actually covers. If a manufacturer refers to a carbon footprint calculation, ask what was included in it and, equally importantly, what wasn't. And importantly, ask how the sauna has been designed and built for long-term use.

We won't have a perfect answer to every question. But we'll tell you what we know, and we'll tell you when we don't.

That's why I welcome the direction the EU is taking. In the end, this is about something quite simple: being clear about what you can actually support.

At Hetki, we'd rather make a smaller claim we can stand behind than a bigger claim that sounds better.

Janne Oksanen

Founder & CEO of Hetki Finland