Showers are one of the biggest energy guzzlers in the home. But now, the technology to change this has been given the green light. With type approval and the go-ahead from industry bodies for its heat-recovery floor drain, the start-up company Enduce is ready to enter the market.
I Sverige är vi generellt sett duktiga på att energieffektivisera fastigheter. Ventilationsluft värmeåtervinns, högeffektiva fönster installeras, drag tätas och vindar tilläggsisoleras. Men än finns det mer att göra.
– Hushållets i särklass mest effektslukande och energikrävande aktivitet, att duscha, har ingen gjort något åt. En genomsnittlig dusch drar motsvarande mängd effekt som en elbil i motorvägsfart, och den energin spolar vi ut i avloppet, säger Henrik Hagman, grundare av startupbolaget Enduce.
Energiåtervinning integrerad i golvbrunn
Hans idé om en golvbrunn som återvinner värmeenergi medan vi duschar för att förvärma inkommande kallvatten, har stegvis utvecklats sedan 2008. Den patenterade tekniken är relativt enkel i sin utformning. Inga pumpar, ingen elektronik, inga sensorer – det är gravitationen som får golvbrunnen att fungera. Målet har varit att ta fram en produkt som ligger nära en vanlig golvbrunn, med en värmeväxlare och integrerad energiåtervinning som den stora skillnaden. Enligt oberoende mätningar hos RISE möjliggör Enduce golvbrunn en energibesparing på upp till 75 procent, jämfört med en traditionell golvbrunn.
– Vi vill transformera branschen och bli vad LED-lampan har blivit för den traditionella glödlampan. Vi ser att det inte längre finns någon anledning att spola ut stora mängder energi utan återvinning, säger Henrik Hagman.
Enduce fick en första större finansiering 2021 från Energimyndigheten, och i ett senare skede puttade myndigheten in ytterligare tre miljoner för att möjliggöra vidareutveckling och kommersialisering.
– När vi tog kontakt med RISE 2022 hade vi redan gjort ett stort antal iterationer för att komma fram till en teknik som faktiskt kunde typgodkännas. Antalet beräkningar, dokument, registreringar och formulär som man behöver fylla i när man utvecklar och marknadsintroducerar en ny produkt har faktiskt varit bortom min vildaste fantasi. Typgodkännandet har varit den enskilt största delen, säger Henrik Hagman.
Erbjudande:
We want to transform the industry and become what the LED has become to the traditional light bulb. We see that there is no longer any reason to waste large amounts of energy without recycling.
One product – three categories of building regulations
A type approval is proof that a product complies with the Swedish National Board of Housing, Building and Planning's building regulations. From July 2025, updated rules will apply to "promote new technical solutions and open up the use of new materials and methods". The Swedish National Board of Housing, Building and Planning writes on its website that the previous rules meant that construction was locked into existing solutions.
When the Enduce floor drain had to be tested and approved, the rules had not yet changed. Anders Rosendahl, certification engineer at RISE, explains that the project required unique preparation:
– There is nothing like this on the market, so at an early stage our product certification experts carried out a requirements survey to see which parts of the Swedish National Board of Housing, Building and Planning's building regulations needed to be taken into account when investigating what this product should be tested for. Enduce had to meet the requirements for a floor drain, but also the requirements for a wet room installation product, he says.
– The requirements cover everything from the fact that the heated water must not be allowed to stagnate, as this can lead to bacterial growth, to ensuring that cleaning functions are in place to prevent blockages and leaks.
– There are many aspects that this product both meets and has been tested for, says Anders Rosendahl.
"The people at RISE have been outstanding without exception"
– Developing a technology that works and creates benefits is one thing, but getting it approved by any kind of regulatory system can be a very long journey, as we have seen. My understanding is that the process is designed for innovations to come from established, profitable companies that have three years to introduce a new product. For a start-up company, the product itself is what you are seeking approval for, and it will form the revenue base, so you have to rely on financial support during the process, says Henrik Hagman, who continues:
– Having said that, the people we have had contact with at RISE have without exception been excellent. Benevolent, competent, responsive, objective people who have helped to move this difficult process forward.
Next challenge: Large scale distribution
With type approval and the long-awaited green light from industry organisations such as Säker Vatten, and a place in the FabrikantAccept database required for plumbing and water companies to dare to install the product, the door to large-scale commercialisation has opened.
– Our ambition has been to develop something so affordable that the product becomes available to everyone. It's a bit like the IKEA approach in that we want to offer environmentally friendly, climate-saving technology to everyone, not just the very richest. The next challenge is to make it widely available to the market, scale up quickly, and demonstrate the benefits so that everyone understands, says Henrik Hagman.
How the floor drain works
- In a shower with an Enduce floor drain, the cold water takes an extra 'turn' before it mixes with the hot water (from the domestic hot water tank or district heating centre) in the shower mixer.
Rather than being channelled directly into the mixer as is traditional, the cold water passes through a plate heat exchanger in the floor drain. Here, a large number of metal plates lie next to each other. On one side of these plates, the incoming cold water flows. On the other side, the used, hot shower water flows down the drain. The heat from the used water is conducted through the plates and transferred to the cold water without the two streams of water mixing. - The cold water is heated to around 33°C. This means that less "new" hot water needs to be added to the mixer to achieve a comfortable shower temperature.
