We use non-toxic materials & products! Green cleaning, voc-free paint, PVC free, …

Enjoy some lush original 1900 carpentry! Fully restored and insulating to save energy and block street noise.

Get ideas from yök for saving resources at home! Less water, energy and stuff = more savings. 

yök Casa + Cultura office before and after

The eco-renovation of yök Casa + Cultura is still in full swing but this week we moved into our office. This small (35m2) yet multi-functional space, equipped with a kitchen and toilet, serves as our reception as well as event space. The best thing about it: our terrace, overlooking Barcelona.

imageyök Casa + Cultura’s Instagram/via

Up here on the 8th floor, an extension from the 70ies to the original building from 1900, there wasn’t much to salvage. However, we decided to restore the traditional terrazzo we discovered under a glued layer of cork in order to save extra material like for example a cement or wooden floor.

imageyök’s Instagram/via

In order to make the space cosier, we added wood to the interior. Our carpenter David used some salvaged timber sleepers he obtained from the Catalonia Railway Museum in Vilanova, a nearby town, and turned them into a beautiful interior.

imageyök Casa + Cultura’s Instagram/via

The kitchen countertop, ECO by Cosentino, is also made in Spain, from upcycled material such as mirror, glass, porcelain, earthenware and vitrified ash. The company claims that 94% of the water used in its manufacturing process is re-used. We also like that it is highly durable and easy to maintain.

imageyök Casa + Cultura’s Instagram/via

All our appliances are energy-efficient and A+ or A++ certified. The AC, which we hope to use only in the very hot or very cold weeks, is also A+ certified, both for heating and cooling. In order to minimise the use of the AC/heater, we made sure we can cross ventilate the space. Insulation is also key. The ceiling is insulated with a layer of Isonat wood fibres and Knauf’s A+ certified low-VOC drywall. We installed new wooden doors with double glasing and are in the process of installing a plant pergola on the terrace to create shade on the outside facade. If our budget allows it, we will install a vertical garden to further insulate the space from the outside.

imageyök Casa + Cultura’s Instagram/via

We also took care of basic things like VOC-free paint and a DIY lighting installation made from a minimum use of material and LED light bulbs. Our light switches and plugs (large image above), collection 5.1 designed by Oriol Guimerá for Font Barcelona, are made locally from brushed stainless steel which makes them very long lasting and recyclable.

We use second hand objects and locally made furniture from certified wood, and are looking forward to receiving the clamp-a-legs by DE VORM, to make flexible tables with salvaged table tops.

Although we had our doubts about Roca’s w+w toilet (a toilet with an integrated sink and gray water recycling system) due to the large amount of material it uses and its high price, we realised that it was the only way we could have the bathroom in the small space suitable for it. Of course we like the fact that it recycles the gray water.

imageyök Casa + Cultura’s Instagram/via

Barcelona’s tap water isn’t very nice to drink unfiltered, so to avoid bottled water we installed reverse osmosis. The wastewater is being collected in a tank on the roof so that we can use it to water the plants and for cleaning. The kitchen tap, L20 by Roca, has an integrated aerator and cold-start.

On our to do list are bee-friendly plants on the terrace to help cool down the place while providing food for urban bees, and, a washing line to dry our clothes energy-free. All of this will be ready when yök Casa + Cultura opens the apartments from july 28th!

An update from the #ecorenovation via our Instagram feed. Oto has started with the zero-VOC paint, José has stripped all the old paint of the original carpentry, Hector and the team from Anoche are busy with the lighting, David is finishing the wood work in our #aticoyök and Marcello and Petz have assembled the #MOByök after lasercutting the pieces at the FabCafe Barcelona.

Román and Isonat Flex insulation material made from wood fibres

Rockwool, or mineral wool, is still commonly used here in Spain for insulation due to its low cost. I read up on it, and as Lloyd, “am still confused” whether this classifies as a green building material or not. Since it is made from a non-renewable material (volcano stone), requires a high amount of energy during production, and is not recyclable or reusable (since we have to cut it to size and there is no take-back program set up), we concluded that we could find a better material.

image© Marcello Cannarsa

We looked into cellulose made from recycled paper that is sprayed in between the drywalls, but had to discard this idea due to the high cost, and because the cellulose is difficult to get out for recycling in the future. Since you need to hire special machines for the installation, this only makes sense economically if you have quite a lot of walls to insulate or are constructing a new building.

image© Marcello Cannarsa

We kept looking for eco-friendly alternatives and found Isonat Flex by the company Buitex, made in France from wood fibres of pruning and cleaning local forests. This semi-rigid material is still roughly three times the price of mineral wool, but at least as easy to install and much less harmful for the person handling it. It fulfills all the criteria for both fire-resistant, thermal and acoustic requirements and to us it turned out to be the greenest alternative available. Here is why:


According to Buitex, these plant-based insulation products last the same and even longer than the more traditional ones. Their research lead them to select the best performing ingredients to avoid clumping and degrading, and they estimate it performing during 30 to 50 years.

image© Marcello Cannarsa


In order to obtain high durability, Isonat Flex is made of more or less 85% wood fibres and roughly 15% recycled polyester. We weren’t too happy about this fact at the beginning as adding a non-biodegradable material (polyester) results in the wood fibres not being compostable any more. (Even though the distribution company here in Spain claims it to be a compostable material…)

However, we understand that mixing in a technological material is probably necessary to achieve quality and longevity, and what convinced us is the fact that Buitex takes back used insulation materials to recycle properly (upcycle) at their factory in France. The same is done with surplus material during production and left-overs from building sites.

Easy installation

Our builders confirmed that it was not more difficult to apply Isonat Flex to our A+ low-VOC drywalls than mineral wool. All you need is a mechanical saw to cut the material to size. Having said that, correct installation is key for this, or any semi-rigid insulation material, to work.

image© Petz Scholtus

Natural comfort

We are glad to obtain insulation quality by means of a renewable material such as wood. The idea is to help regulate the temperature in both summer and winter and obtain a maximum comfort all year round.

In order to reduce heating and cooling costs, apart from insulating the walls, we will also install double glazing in the traditional wooden windows and balcony doors, and install a green facade to insulate our top-floor office space.

Here a few more photos from our Instagram feed. From top to bottom we have Fem Ferro building a long-lasting, fully recyclable cabinet for our terrace, Tudor figuring out how to install the w+w, Vitali the electrician, and Maño the carpenter.

I would like to share with you our reasoning behind choosing the sinks for our bathrooms at yök Casa + Cultura. The ninth point of our manifesto explains our criteria quite well:

9. Apply good design (useful, beautiful, fun, detailed, eco-friendly, functional, affordable, long-lasting, honest, local) to everything: interiors, business model, service, activities, and shop.

Good design is what we strive for and we are also on a limited budget. So what we thought was the most eco-friendly solution at first, was to go for as less material as possible. After all, the most eco-friendly material is the one we don’t use! For that reason, a few years ago when designing the R3project, I came across the Kalahari sink, designed by Ramon Benedito for Roca:

A sink made from one single piece of ceramic. The fact that it is a shelf and a sink in one piece minimises the material used drastically. Whether the aesthetic end of life is prolonged as well is arguable but it definitely creates less waste than a standard sink.

© Roca

Porcelain has the big advantage of being long-lasting, at least on a technical level. But how many sinks get thrown out due to an emotional reason; because it is out of fashion or we grow tired of it. To foresee the emotional longevity of things is often harder than making stuff last physically. Even though we found some nice locally-produced designs, the fact that porcelain is difficult to recycle (we would be talking about downcycling), kept us looking for other solutions.

When it comes to materials suitable for sinks, plastic is very funky and especially recyclable. We found the LTB sink by WET, made in Italy. These sinks have the advantages that they are very lightweight (2kg!) and made from 100% recyclable LDPE. They are easy to clean, child-friendly due to the round shapes and pretty much unbreakable. I am not so keen on the optional LED lighting but I don’t think it does any harm either.


Still, while discussing this with my colleague Jenna Watson, among other things, she reminded us that we should think about the entire life cycle of the sink, and consider its longevity. Does it make more sense to opt for porcelain ones that last more than a lifetime of the bathroom? Waving back and forth between whether to prioritise recyclability or durability, we thought we’d look into finding reused porcelain washbasins. And alas, at Otranto here in Barcelona, we found 5 beautiful sinks that were salvaged from an old B&B. Of course we were lucky to find enough reused sinks that fit in our spaces.

yök Casa + Cultura’s Instagram/via

Buying second hand can be exhausting but to me it is also fun. Once you find the object, you usually also have to invest some time to fix it up. In this case, we need to find fitting low-flow faucets, cover up the remaining holes (back in the days there were two taps, one for cold and one for hot water) and find a fitting drainage system. We believe that all of this is well worth it because we saved some unique sinks from the dump and prevented new resources from being used. Moreover, our washbasins tell a story, thank you for reading it!

After putting up low-VOC drywalls, we are on to the water installation for yök Casa + Cultura’s eco-renovation. One of our goals is to keep the apartments 100% PVC-free. We also aim to use materials in such a way that they can be recycled in the future. And we don’t believe that all plastics are bad. When it comes to the water pipes, we think that a non-toxic plastic plumbing system is the better solution to the traditional copper one.

© Petz Scholtus

For our pipes, we use PEX, or crosslinked polyethylene, by Uponor. The tubes are flexible, easy and quick to install, and long-lasting. Uponor explain on their blog that “the process by which copper is mined, refined, transformed into end products, and then used—such as pipe—is very energy intensive, using a great deal of non-renewable energy during its lifetime. In fact, if a Life Cycle Assessment (LCA) is undertaken for both PEX and copper, PEX fare much better. Simply put: during its lifetime, a PEX-based system has a lower overall energy content than a similar system made from copper.”

Copper is indeed more expensive, and even though it is also recyclable, requires a lot of energy to do so. Our workers say that installing PEX is much more comfortable than copper.

© Marcello Cannarsa

Benefits of Uponor PEX over Copper and CPVC according to Uponor:

- Flexible for fewer fittings, reduced leak-point liability
- Resists corrosion, pitting and scaling
- Retains more heat in hot-water lines
- Resists condensation on cold-water lines
- Expands up to 3X its diameter to help resist freeze damage
- Connections do not require the use of dangerous chemicals or solvents
- Offers a complete lead-free system from inlet to faucet
- NSF International certification for water purity
- Backed by a 25-year limited warranty on PEX tubing and ProPEX fittings

Last but not least, the PEX we buy in Spain is made in Spain, just like our drywalls.


Drywalls have in the past often been criticised for being “cheap”, nondurable or flimsy, and bad for your health. So we tried to find another solution to divide up the different apartments and rooms for yök Casa + Cultura. Most of the ideas we came up with however, were too experimental, meaning costing too much money or/and time. So we went back to studying drywalls available in Spain and found Knauf.

© Marcello Cannarsa

Knauf’s panels for room partitions and suspended ceilings have been rated A+ regarding VOC emissions in interior spaces. The panels are made of 100% recycled cardboard and natural plaster, of which a part comes from pre-consumer recycling.

© Petz Scholtus

Moreover, this technique allows us to put the new walls on top of the mosaic floor without damaging it. In the future, walls can simply be removed without damaging the original Catalan Modernisme features. No wet material like cement, sand or glue is needed. Another advantage for us is that the material is made in Spain, which reduces the transportation impact, and has obtained the UNE-EN ISO 14006 Eco-design certificate by Aenor.

yök Casa + Cultura’s Instagram/via

The panels are set up using standard metal guides that can easily be recycled in the future. The panels itself can also be fully recycled, separating the plaster from the cardboard. This however, is hardly being done in Spain at the moment because it is currently cheaper to dispose of the panels as landfill, than to bring them back to the factory. Let’s hope that by the time our walls need to be recycled, the company has a take-back program for its material in place!

© Marcello Cannarsa

Instead of mineral wool, we opted for natural sheep wool for insulation. In the end, using drywalls and sheep wool results in much less volume of material than most other materials, and hence in less transportation and packaging. The walls fit all our criteria regarding health (VOC-free), safety (fire-proof), environment (local production and non-toxic), comfort (sound-proof) and cost (easy installation).

At yök Casa + Cultura’s eco-renovationrecyclability is one of the key factors. Even though we didn’t want to throw anything away, some of the original partition walls had to go in order to fit the distribution to our current lives, creating smaller apartments with more privacy.

What is important to us it that in the future, maybe in another 100 years from now, people can go back to the original wall distribution. We are not touching any of the mosaic tiled floor or decorative ceilings. New walls are simply being put on top and below, so that they can be taken out and recycled in the future.

As for the rubble resulting from taking out some of the walls, we had an official company take it away for proper recycling, as required by the City Council. Regarding the current recycling system, this is probably a downcycling rather than upcycling, but at least it is not creating more landfill but serves as material for building works.

The Waste Agency within the Catalan Regional Government (Agència de Residus de Catalunya) explains:

A high volume of construction waste is generated in Catalonia. Due to its characteristics, much of this waste can be reused or recycled. Therefore, due to its importance, there is a specific management programme and management model for this waste. After a period of consolidation in which the aim is to attain the correct final management, the focus will be on prevention, recycling and the promotion of a market for recycled materials.

Everything else we hope to restore, both for environmental reasons (to reduce waste and save resources) as well as emotional ones (to preserve a piece of history and culture). We believe that even a piece of the old wallpaper from the 70s has to stay (image above). Our motto is: first, preserve everything we can, then recycle everything that has to go and lastly, make sure any new stuff is recyclable in the future. Reduce, reuse, recycle! And restore.

Here are some photos by Marcello of the current state of our eco-renovation!

Starting today, I have the pleasure to document our eco-renovation here on Treehugger. Our project is called yök Casa + Cultura, and is situated in the center of Barcelona, Spain. Casa stands for eco-friendly tourist accommodation and Cultura reflects the true local culture in Barcelona, not that of tourists. yök (from the Catalan word “lloc” meaning “place”) will be a social hub where visitors and locals come together to share good design and a sustainable lifestyle (read the yök Manifesto here).

What I will write about in the following weeks is the step-by-step transformation of an over 100-year-old space into three eco-friendly apartments and an office, while respecting all its original features. These include fabulous “Nolla” floors (colourful ceramic mosaic tiles), gorgeous woodwork and stunning high ceilings with decorative features, all in the style of Catalan Modernisme from around 1900.

Our renovations started in February 2014 and we hope to finish in June this same year. The aim is to use materials wisely, making sure they are recyclable and cradle to cradle where possible. A special effort is being made to reduce the water and energy consumption in the apartments. Moreover, we give priority to locally designed and produced materials, products and furniture to reduce transportation, support the local economy and promote the regional culture. The trick is to create apartments in which responsible living is possible without sacrificing the experience.

We are delighted (pun intended) to be working with Jordi Ballesta and his team at Anoche, to make yök a well-illuminated and at the same time energy-efficient place. 

With the help of Xavier Mor from Renòwatt energy solutions, we were able to decide on the best systems for heating water and heating and cooling the space, while maintaing a small CO2 footprint. More information soon!