Self Grown Hemp for Construction

Wouldn’t it be ideal if you could grown your own hemp and then use it to build your home? 1 or 2 hectares of hemp stalk is potentially all you need to harvest enough building materials to build a house. Imagine that – growing your own house!  … but it isn’t a simple thing to do.

The hemp plant has four elements: seeds, leaves, fibers and a wooden core. The part you need for construction is the wooden core – also called the hurd or shiv. Separating it from the other elements of the plant requires effort. You need to grow the hemp, deffoliate it (remove the leaves) before harvesting, harvest or remove the seeds, harvest the stalk, let it ret (start decomposing so that the fibers can be separated from the hurd) and then decorticate it.

This finally step of decortication seems like the greatest obstacle – this is the process of separating the fiber and the wooden core. It can be done either through massive manual labor (of which I don’t yet have all the details – but it involves collecting the harvested stalks into small bales and then beating them to separate the fibers and wooden core) or in an industrial process. The indutrial process is usually designed to extract the fibers, the actual wooden shiv is simply a left over of that process.

It would be so much easier to grow your own construction hemp if decortication could be avoided – and this may be possible but my understanding is that it depends on the climate you live in. This research paper on Hemp-Concretes claims that it is possible to create hempcrete using both shives and fibers – BUT it is important to note that the research focuses on the structural aspects of the resulting hempcrete. It does not address the effect of fibers on insulation and breathability of the hempcrete.

Introduction of fiber to the hempcrete mix can cause humidity problems. When fibers are clumped together they tend to draw moisture and that is not something you want to happen in your wall. According to Steve Allin it is possible to add 5%-15% of fiber to the mix but not much more. This may be less of an issue in a hot and dry climate – but otherwise the risk seems unwarranted.

Maybe when the hemp industry matures it will be possible to cultivate stalks with very little fiber and a massive wooden core – which could then be used in whole? For now though it seems that self-grown hemp is not a feasibly reliable option for construction unless you have the means to decorticate it.

What does Ecological mean in Romania?

We just got back from a meeting at the school of architecture in Cluj. It was a good meeting with some followups to look forward to. But we did meet with some skepticism – “ecological building is a fashionable thing” … I agree that there is a lot of fashion in ecological building – even intellectual/academic fashion. I couldn’t possible put it better then George Carlin did:
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But, I also think it’s important to be able to discern between the bullshit and the real shit. Ecological building should have direct impact on quality of life – otherwise it really is a fashionable indulgence. So I thought to take this opportunity to share some of the things I consider to be ecological in the context of building a rural house in Romania.

Warmer

My general impression of homes in Romania (actually Israel too!) has been that they are cold in winter (public spaces are generally much warmer then homes I have visited). This is a combination of poorly insulated homes and fairly expensive fuel resources.

In cities gas is the primary source of heating energy – it is very expensive and building-blocks built of concrete are poor heat containers. We are struggling to keep our gas costs under control and can just manage to keep the apartment at 19-2o degrees celsius.

Village homes are usually poorly insulated (despite super thick mud-brick walls) and even though firewood is relatively cheap, it is expensive when you live on what you can grow … and you can’t grow money. So those that do have fire-wood used sparingly – again, just enough to keep out the cold.

Hemp is said to be one of the best insulating construction materials. This means that the same quantity of fire-wood that a village home uses ine year to just-barely keep the cold out can be sufficient for keeping the same house comfortably warm for 2 years (if not more!).

Better Air

I’ve mentioned before that almost every apartment or house I’ve visited in Romania suffers from humidity problems. Humidity is locked inside the house and it’s walls (you have to see it to believe it – water running down the windows and accumulating in pools on the window-sills). It turns into mildew which leads to respiratory problems.

Hemp is also said to be a healthy building material. It creates a permeable wall that absorbs excess moisture on the inside and releases it on the outside. It does this without any insulation or sheathing materials. It is a natural quality of a properly built and well ventilated hemp-masonry house.

Self Grown Homes

Romania used to be a major supplier of hemp-fiber – which means that the land here is good for it. As a rule of thumb one hectare of land yields enough crop to build a house. Oh and hemp requires no herbicides or pesticides, kills weeds and renews the land in which it grows. Oh and it is said to have huge potential in world markets for zillions of applications. Oh and its seeds can be used for food and oils which are magically healthy.

Almost every Romanian farm has vast farm lands – which means that most Romanian farmers can potentially grow the hemp they need to build/rebuild their homes.

Simple to Build

Hemp masonry is poured around a wooden frame – which a small group of people with basic coordination and tools can build in a week or two. Romania is gifted with vast amounts of excellent and afforable wood.

Hemp building requires the most rudimentary frame building skills – many framing complications involving insulation and sheathing are completely obsolete do to the nature of hemp construction.

Bringing the Toilet Home

Our new friends, Ina and Sabine, eloquently described the challenge of reviving the image of village homes in Romania “Bringing the toilet – a freezing outdoor shack with a hole in the ground – indoors”. The ecological implications of technologies (they are so simple – that calling them technologies, though true, can be misleading) such as dry-compost make this easy and afforable to do. Running water is used to evacuate waste from the home and then a simpleto-install and super-easy-to-maintain mechanical system separates water and waste and converts the waste into dry and usable compost. So much cheaper and easier then digging a hole in the groun and installing a sceptic tank that needs chemicals, can demand unpleasant maintenance to run and a periodic evacuation service.

So, All Fashion Aside …

We are still beginners when it comes to ecological building – but we are committed to this path. We have a very limited budget to create our home. A limited budget comes bearing gifts of simplicity – complicated, expensive indulgent technologies are just not an option. Ecological means simple solutions, many of which are do-it-yourself (or do-it-with-your-friends), based on and respectful of natural available resources.

That’s it, direct simple things that come together to make life good.

Passivhaus

Introduction

Passivhaus is one of the terms out there in eco-green-sustaintable building land. It may look like its spelled wrong but that’s because its originally from Germany. It represents a very strict and high standard of energy efficiency in a building. It isn’t (yet) an official requirement or standard but it is gathering momentum as an unspoken standard.

There are three complementary core ideas behind the idea of a Passivhaus:

  1. Complete and thorough thermal insulation of the house which prevents conductivity of heat from the inside-out or the outside-in.
  2. Complete air-tightness which prevents exchange of heat through air leaks (windows, doors, pipes, chimneys … every opening needs to be sealed!).
  3. An efficient ventilation system that both exchanges air (from the outside and the otherwise airtight house) and does so without losing heat.

This is one of those images that is better then a thousand words. The apartment building on the left is standard/traditional building while the apartment building on the right is built according to the Passivhaus standard. That’s the bottom line of Passivhaus – keeping the heat from escaping means you need to expend less energy to heat the inside.

Extreme!?

I have come across Passivhaus numerous times in recent weeks and my recurring personal impression is that it is too extreme:

  • It seems like more of an academic indulgence then a practical construction practice.
  • It’s objective and success is measured in a single number – the amount of energy needed to heat a square-meter of space.
  • It demands rigorous builing disciplines which require uncompromised excellence in construction.
  • It demands the use of specialized insulation materials which can be expensive (especially if you consider the ecological foot-print involved in manufacturing them).
  • It creates a house that demands constant attention, maintenance and proper use by its residents (every window opened and every hole drilled in the wall is a potential energy hazard).

All of which results in a delicately balanced system: if it isn’t absolutely sealed, perfectly ventilated by a carefully installed system and properly used it just won’t work. There is no room for error. This maybe OK in a scientific experiment but not so for life, nature and people.

In any case it doesn’t feel right for us: we have a limited budget, average construction capabilities, standard building materials, etc. We are going to do the best that we can with what we have. It’s an 80/20 kind of thing – where 20% of the effort takes you 80% of the way you need to go and it would take another 80% of effort to go the rest of the way. We’re aiming for a good middleground – pushing the limits of what we have – but that, by definition, is not enough to go for 100%. Passivhaus is uncompromising, but we live in a reality which demands compromise.

“A passivehouse is cost-effective when the combined capitalized costs (construction, including design and installed equipment, plus operating costs for 30 years) do not exceed those of an average new home.”

Source: PassiveHouse.com

I am hesitant to relate to this statement as that may give it unwarranted legitimacy –  cost is just too narrow a perspective to view ecological housing. But if I do meet it head on, as is, I would say that it sets its sights much too low. I hope to build a house where the combined capitalized costs are much lower then those of a new average home (whatever that is). I also hope to build a house who’s qualitative effects (both for us and others) far outway it’s economic effects.

Maybe Passivhaus is, for the time being, a high-end building experiment? Maybe in time it will spawn accessible, affordable and feasible techniques, solutions, technologies, practices … that can become a defacto standard that simply makes sense to follow? For now, it is out of touch with us and our needs.

Humidity

Having said all that exploring Passivhaus has brought to my attention a factor I had not taken into consideration in all of my energy research: Indoor Air Quality. I have been following a very basic intuition: “generate heat” in trying to solve a problem we’ve been having for many winters: “being cold”. Most of my attention has been on how to preserve and generate heat (space and water) effectively.

I had not given any thought to one of the central themes of Passivhaus: quality of air. Quality of air (assuming there is good ventilation) is strongly effected by humidity … and humidity effects the overal experience of temperature … cold is much colder when humidity is too low and heat is much hotter when humidity is too high. I have experienced the effects of humidity in warm and cold temperatures in Israel and I have seen it (as accumulated moisture and mildew) in almost all Romanian homes I have visited.

I don’t know yet enough about ventillation and humidity.

Hemp

One of the much praised qualities of hemp masonry is it’s breathability. It seems to have a natural tendency to absorb and expel unneeded moisture. I don’t yet have enough information on the overall effects of hemp on moisture, ventilation or quality of air indoors – but I do have a good feeling about the effects of hemp!

Resources

Following are some of the resources I came across and consumed in trying to understand Passivhaus: