📙 The Future of Ecological Urban Living

Great - tomorrow afternoon should work fine if it doesn’t get too late.

Here are the questions that we discussed with @bernardo today. I will integrate his answers into the manual above in the next days. For now, enjoy the questions.

Regarding construction and building conversion

  • Management and budgeting of construction projects. Basically, what is the standard practice to estimate the cost of renovation and conversion of a building. Before going into details (calculating materials needed etc.), hopefully there are good rules of thumb based on building type, size, age and the intended type of conversion? Where do we find these numbers?

Regarding compact living

  • If you had to create a space-saving furniture system for tiny houses, how would you approach this? The challenge is that all the tiny houses are different and space restricted, so the same furniture will not fit everywhere …

  • What are good approaches for splitting a warehouse style space into small living spaces so that the conversion takes up little embodied energy? And ideally, one could still switch flexibly between usage as a large space and usage as smaller spaces.

  • Lighting and ventilation solutions for windowless rooms? Which can happen as a result of space sub-divisions.

  • Modern dorms. If you had the task of designing a modern dorm that is comfortable for ≥6 adults, including couples, how would it look like?

  • Flexible room use. We want to set up a communal living scheme where people do not have fixed rooms but rather get a room only for the time when they are in the space, and based on their current needs. What would be good architectural interventions and interior ideas to make moving between rooms comfortable even if people had to do it every other day?

Regarding minimally invasive conversion

  • Minimal conversion techniques. Which ideas did you practice already or think about regarding minimal, ecologically friendly adaptation of spaces that you occupy? For example, the exposed brick wall idea in the communal kitchen of Bosch Tanneurs. Anything resulting in “shabby chic” optics and that uses salvaged materials (or no materials at all) is highly appreciated.

  • Decorative salvaged materials. What old, salvageable materials can be re-used in a decorative manner to modify rooms in such a way that they look “old, shabby chic and used but authentic, warm and nice”? This relates to floor covering, wall covering and indoor insulation.

Regarding energy efficiency

  • Nice window-less kitchen and living room. Heating-wise it is efficient to have the warmest rooms (kitchen and living room and bathroom, but not toilet) in the center of the building. How to make them nice and livable even though they will have very few or no direct windows to the outside?

  • What to focus on re. household energy efficiency? So far we focus on heating, and partially cooking, as the areas where interventions can yield the most energy savings. Any area we are missing?

  • Office space with small heated spaces. For heating efficiency in the office, we are looking for designs that split a large office into smaller heated spaces while still being a nice place to work, with frequent and good contact to colleagues. A row of small meeting rooms will not do it. If you had to do this, starting from a large footprint office (15×15×3 m), how would it look like?

1 Like

@matthias — I ran across this last year and thought it would match some of the goals to achieve re ventilation. In this case, the site explains how to do ventilation on demand, using a suitable process variable CO2 — the intent is to ensure just enough fresh air gets into the space to ensure everybody doesn’t get too drowsy. This is more of a thing in climates up north where opening a window is ill advised this time of the year :snowman_with_snow:


The author of the site went this route since they found the controls on their heat recovery ventilator to be crude, by only using humidity; and by continuously running at lower fan speed. These days the cost of CO2 and humidity detectors are at the point an automated solution could help optimize the air in a living or working space, and be controllable enough based on load.

I suspect I am not the only one that has considered dozing off in a stuffy conference room. :laughing:


Aww, that’s a great idea for a control algorithm to save air heating energy, thanks a lot for adding it here! It already gave me the inspiration for some more ideas:

  • I should use this system in the truck where I live. Also I should test CO2 levels after 8 hours of being in there with the windows closed. Right now I keep the window open a bit at night, even in winter, fearing that I might suffocate in that close tight plastic box otherwise :smile:

  • To keep air quality alright in small heated spaces located in larger unheated rooms, automatically adjusted ventilation openings controlled by CO2 level might be all it needs. No fan or heat exchanger needed.

1 Like

@matthias — regarding:

  • Management and budgeting of construction projects. Basically, what is the standard practice to estimate the cost of renovation and conversion of a building. Before going into details (calculating materials needed etc.), hopefully there are good rules of thumb based on building type, size, age and the intended type of conversion? Where do we find these numbers?

As an initiative, I reached out to local engineer who specializes in restoring and renovating older historic buildings. He got back to me in a few moments (!) but mentions it is a bit more nuanced, since it really is site specific.

Currently there is no industry wide rule of thumb for costs based purely upon building type, size and age. There are a few different costing approaches for getting rough order of magnitude (ROM) cost estimates. The type of conservation and the required intensity is going to be a factor.

Typically a starting point is a professional review of the site, and they will make a ROM estimate based partly upon the rules of thumb they reference and partly upon their own experience. I have often heard references to the dollars per square foot based upon building condition and end goals – but they do vary between professionals.

Not sure that helps much, but this is an example of the challenge for conservation of old buildings. There are just enough exceptions to every rule it can be dangerous making rules. The greater unknowns tend to be the factor that scare stakeholders from following best practices, because they worry about what can go wrong – taking solutions that cost more (both economically and ecologically).

The last sentence (emphasis mine…) here is a bit of an eye opener; since I suspect through experience that he has lived through this, where unlikely consequences drive the redesign to be bigger in scope than is actually needed; it’s not rightsized. Unfortunately, I’ve lived through this also, wayyyy too many times. I would suggest that this point should be made as a risk in this document…


Some intermediate results from today, calculated to make The Reef a 20-person household with solarpunk :sun_with_face: heating:

Let’s put a 5.66 m diameter and 6 m high water tank into the center of the building, insulate it with 40 cm styrofoam and connect it with heat pumps powered by 27 m² of solar panels during the summer – then we have a zero-emission space and water heating system for the inhabitant’s heat requirements during all winter in central Europe. What’s more, operation costs are 46% lower than burning natural gas (!), which means there will be no economic reason for burning fossil fuels for heat anymore.

This assumes that compact living, heated clothing, small heated spaces and other ideas from the document above lower heat requirements to 20% of current average values already – which is actually easy. The detailed calculations are in section “3.16. Seasonal heat storage with ASHP charging”. Since this sounds a bit too good to be true, @trythis is invited to poke holes into the idea :wink:


Avoiding AC conversion. Additional cost reductions can be realized by running the heat pumps on direct solar DC electricity. To adapt to available energy supply, heat pumps would either run at variable speed similar to water pumps that are already available for this purpose, or multiple heat pumps would run in parallel to scale consumption with production. This avoids the investment in inverters and the 6-8% conversion losses of converting DC to AC electricity

You may want to take inspiration from a scuttlebutt denizen who worked on the opposite problem; refrigeration. (@)joeyh did a batteryless offgrid fridge for keeping his food. Programmed in haskell, because.

Additionally, even DC powered items may require switching elements and loss for variable speed operation. In the case of AC inverters, most have a ‘dc-link’ stage prior to the H-Bridge; most will permit direct DC in connection on these terminals with proviso for proper overcurrent protection.

Many multi motor applications I have seen are set up in a one variable speed, many single speed topology; where the matching of the demand and the supply are compensated by the inverter; and the single speed starters are dispatched by a plc.

I’m a huge fan of this method for solving for heating demand; https://de.wikipedia.org/wiki/Heizlast . I ran the numbers on my “cabane” and found the heating demand is around 100W/ºC. Another rule of thumb I have seen is the 70l of storage per kw of biofuel heating capacity:

A well-insulated water tank will keep water hot for a few days until the water storage temperature drops. The size of the hot water storage can vary from 50-70 L/kW (4.0-5.5 U.S. gal/1,000 BTUh) of boiler input power depending on winter weather for small manual biomass boilers. Since it requires approximately 1 kilojoule (1 BTU) of heat to raise the temperature of 454 g (1 lb) of water by 0.55°C (1°F), a 2,250-L (600-U.S. gal) hot water storage tank operating with a design temperature difference of 22°C (40°F) will store 60 kWh (200,000 BTU). That volume of water storage can hold enough heat to meet the January average domestic heat load of a 205 m2 (2,200 ft2) home with good insulation located near Ottawa, Ontario, for 7 hr. Loading the biomass boiler twice a day will meet the peak daily demand if using a properly sized water storage tank. – http://www.omafra.gov.on.ca/english/engineer/facts/14-009.htm#7

I will admit I haven’t checked your numbers out, and just providing this as another datapoint :smile:


@matthias — Another datapoint from lowtechmagazine providing some of the rational for communal living.º

A 2002 investigation of firewood consumption in traditional houses in Nepal measures the annual firewood consumption per household to be between 6 and 33 m3, which corresponds to between 35 and 165 Gigajoule (GJ) of energy. [14-16] This seems quite a lot in comparison to the total energy use in contemporary households, which is around 75 GJ per year in Germany and around 105 GJ in Canada.
However, the average Nepalese household participating in the research consisted of 5 to 12 people, while households in modern societies have shrunk to little more than two people. In the Nepalese households under study, energy use was between 2 and 33 GJ per capita, while another, more recent research paper on firewood consumption for heating, cooking and lighting in Nepal calculates a per capita use of roughly 2.5 to 10 GJ of energy per person per year. [17-18] In comparison, total household energy consumption per capita is around 30 to 40 GJ in countries like the Netherlands, Germany and Canada.

º I subscribe to lowtechmagazine via rss; and get new articles when they come out :smile:


Oh, hello to a fellow Low Tech Magazine subscriber :blush: I just finished reading that same article!

These numbers from Nepal are all the more surprising given the kind of draft-rich, uninsulated mud-and-stone houses that comprise the “average Nepalese household” in 2002. It basically means this (picture I took in 2015 in Rasuwa district … it’s a natural cut-away presentation created by the earthquake, so it’s easy to see how the walls and inner structure were made):

But what they lack in insulation, they make up in compact living. One could even say that heating is 80% just a psychological problem: if you enjoy being close with the people around you, you can cope with 80% less heated space.

1 Like

The mass of 27 cubic meters of water is around 27 tons. As long as you are at ground level (or below) this could be manageable.
But if you plan to go any higher the structural support requirements will be massive - e.g. really thick concrete walls (really bad CO2 footprint).
Other points to consider:

  • In terms of hygiene it is often better to keep a smaller volume hotter (70°C ?) and mix it down with cooler water. That is if you want to use the water besides thermal mass.
  • If for some reason you have a particularly bad year, how do you best avoid coordinated failure? I would hope outright freezing (leading to destroyed container) can be avoided.
  • 27 tons on site are a huge risk, esp. once the things age. Catastrophic failure might be rare, but even gradual leakage would be a major headache.
  • In seismically active areas one would have to look very, very closely at the implications.
  • 27 (plus insulation) cubic meters will take up a significant footprint per person, even more so if the container is round, and worse, has to sit in the center where it gets in the way of everything.
    This makes me wonder if you would not better turn it into a somewhat thinner column that may be easier to mass produce (extrusion), reinforce it with a fiber sleeve (recycled glass or pitch based carbon), and partially bury it?
  • May require added ground fortification, problematic for retrofits, not suitable on every terrain type.
  • Sensors for leak detection would be needed, but tech has made a good bit of progress on that front in recent years (incl. smart fabrics).
  • Multi-party homes would be interested in having the worst insulation on their parts of the tank, resulting in a race to the bottom dynamic.

A couple of pro-points:

  • Water is a concern in many places, so having quite a bit of it on hand is generally good, and potentially a virtuous circle. Germany is still “littered” with public wells, back from the WW3 planning days - this would be even more relevant for most places.
  • Heat is often a underappreciated energy storage solution. Provided it does not raise too many other costs or complications it is often the most long term sustainable of “batteries”.
1 Like

Cool idea. We had a similar one - ZWISCHENNUTZUNGSCONTAINER … and we bring it to live not as an actual container but as a network of People sharing stuff that moves from one temporary space to the next :smile:

1 Like

great idea. want do build a prototype for this.
will use these kind of boxes … standardized size that fit on EU palette

1 Like

Good idea! Euroboxes are reasonably strong, waterproof and cheap. If you’d want to do that for a community, you could get large amounts in used condition from industrial facilities (I once got about 100 of them on eBay, for ca. 4 EUR per piece, delivered on two pallets).

The challenge seems to be to find plastic Euroboxes that are accessible from the side, like a shelf or with a drawer. I am not aware of this type right now, but without it will be challenging to access boxes when stacked.

I had this very issue for years as all my furniture is made from boxes, and eventually transitioned to a box system with side access. It’s the Zarges Mitraset system and it is Eurobox compatible. But sadly not suitable for mass use or prototyping as they are hard to find used and too expensive new. eBay Germany sellers always have some on offer, but most offers are rather expensive (example).

1 Like

yes, this is a challenge … partly this can be solved by placing boxes on shelves in order to move them easily in an out of the stack.

with this process methane will be generated as a side product, which in turn can be used for cooking/heating … see https://www.designboom.com/architecture/catrina-stewart-color-for-a-green-farmhouse/

While researching something else, came across this:

There is an eco-village being planned for Bergen, in Norway:

1 Like

found this “hub” for urban villages in Switzerland … https://www.urbanedoerfer.ch/uber-uns … just getting started


live now … Ruralplayground … connecting rural and urban … https://www.facebook.com/bertola.bergstrand/videos/10157334694371475/?notif_id=1596698001989291&notif_t=live_video&ref=notif

Ha. Bert-Ola is an old contact of @nadia’s. Kind of lost sight of him around 2014…

1 Like

@bert_ola you mean :slight_smile: