Big Water Ouch

The day before yesterday I was watering our raised beds. We shouldn’t need to water the raised beds but we do because (a) we built them late in spring (its best to build them in the fall) so they did not have an opportunity to fully absorb water; (b) because they are still not properly mulched. As I was moving through the beds the water pressure in the hose began to drop and quickly diminished. With some trepidation I went to check the problem.

First I checked that we still had electricity. Check. Then I went to make sure that the pump was not idling (struggling to pressurize) and it was. I unplugged it and plugged it back in and after some struggling it managed to pressurize. Check. Then I looked into the well and it was empty. Not check. Ouch. Big Ouch.

We thought that maybe the springs in the well had gotten clogged and needed to be cleaned. First thing, I took a bunch of empty plastic bottles and went to bring drinking water. Then Andreea called Sammy – the guy who cleaned our well last year – and asked him to come again. He came yesterday evening. We most of the remaining water on the raised beds and Sammy went down to check things out. He did a bit of cleaning up … there wasn’t much.

We overused our well. It is our only water source. It is summer. It was fine last year but last year we weren’t watering raised beds and we weren’t showering much. The showering isn’t nearly as demanding as the watering … so my assumption is that the watering drained our well.

Most people here do not water their fields. They simply can’t. Those that do dig small lakes … deep enough to penetrate the aquifer and draw water from it  … they don’t do it from their house wells. Though our raised beds are a relatively small garden … watering them is simply not possible with the supply of water that we currently have. This is where the rubber meets the road … how resilient will mulched raised beds turn out to be? Time will tell.

The well is filling up again … but it isn’t reaching the level we know it to be. Painful lesson learned.

Tires Together

One of our core projects here at Bhudeva is building our future house. We have been doing a lot of research on sustainable and ecological construction and we have been facing many challenges in bringing existing knowledge into context for our life here in Romania. Our latest design envisions a mostly underground house that will provide us with a year-long steady temperature of 21c without any energy inputs (neither for cooling in the summer nor for heating in winter). The core of our design is based on the concept of Earthships. At the heart of Earthship construction are massive walls built of tires that are packed full of earth.

So for many months we’ve been looking and asking around about tires here in Romania and this is what we found out:

  • Most tire dealers and repair shops sell some used tires that barely have treads but can still just barely be driven for 15-20 ron a tire (just to be clear – they are sold to people with old cars who can’t afford new tires).
  • Tire dealers are required to “recycly” through the state (represented by licensed operators) a certain amount of tires to offset new tires that they import.
  • The dealers are paid a symbolic 50 ban per tire collected from them.
  • Most of the collected tires are then sold off to different uses . Some are recycled (yey!!) into products such as car mats … however …
  • Many (we suspect most) are sold at a premium of 10-20 ron per tire (purchased in quantities of tens of thousands) to cement manufacturing companies (and their likes) who use them as fuel (boo!!) – it seems that a single tire contains a equivalent of 7.5 liters of oil!
  • We know of at least one giant pile of tires in Cluj-Napoca that is just sitting there slowly decomposing in the sun. We assume that other such piles can be found all over Romania.

Used tires is a waste product we (especially those of us who drive cars) are all responsible for creating. The concept of Earthships (built with earth-packed tires) was born out of recognition that this huge source of waste (available all over the planet) can be put to good use in creating houses (which it would seem are also needed all over the planet). Any recycling of tires requires high energy inputs (often starting with shredding). The thought of all the toxicity released when tires are burned as fuel (a single tire contains a equivalent of 7.5 liters of oil!) is mind-boggling. When used to build Earthships the tires are used as is and because they are completely buried they do not decompose or release any toxic gases (which they do when exposed to the sun).

Whenever we speak to someone in Romania about needing tires we quickly encounter an opportunistic greed. Regardless of the “asking-price-per-tire” we would also need to find a solution to sort through tires and have them brought over to our place which incur additional expenses. All this caused us to rethink about construction with tires – suddenly it seemed that concrete blocks that easily snap together would be much cheaper (and way faster to build with) then working with tires. However we really don’t want to resort to massive construction with concrete … so we scratched our heads and though of you … yes you 🙂

Inspired by the awesome waves of goodness we encountered with the introduction of Cutia Taranului we decided to once again try collaborating with you – our fellow Romanians. Also in the spirit of Cutia Taranului we realized that the best way to get tires would be to go around the existing system rather than through it. It boils down to this … the next time you buy tires we would like to ask that you keep your old tires, don’t leave them to be used opportunistically as fuel.

Now look at your old tires … what do you see? Look closely … you are holding a personal invitation to visit with us at Bhudeva including at least a pleasant conversation, a tour and a tasty cup of herbal tea … and best of all you have become a contributer to a unique experiment in sustainable construction taking place here in Romania.

For our house we are going to need about 2000 tires (though we have other structures planned … so we will try to collect much more). Tires come in different sizes which are indicated with a combination of numbers printed on them. All you need to look at is the first number – the one that has the letter “R” in front of it. We need tires that are labeled as either “R15” or “R16′”. The larger “R16” tires will be used for the base of our walls and the “R15” tires will be used on top of them for most of the wall.

Lastly … since we are talking about garbage 🙂  We are also going to need empty cans, empty wine bottles and used cardboard boxes. So if you are already holding on to tires an invitation to visit Bhudeva then please  hang on to these things you may be tempted to throw out 🙂

Since tires are not often changed this initiative may move a bit slow so … please do spread the word to your family and friends 🙂

 

Water – Pump Installation

Finally we get to the point – installing the pump. This just goes to show you how long a journey it was … at the end of this post there will be an image of joyous water flowing 🙂

However as I write these words we are are at the peak of winter (soon the hardest part of winter will be behind us) and we have no running water due to freezing problems. I will try, in this post, to address what we did, what should have be done and what we will be doing to fix this problem so that hopefully, next winter, water will continue to flow.

What We Did

The pump was installed on the concrete stage set for it in the concrete box. It was bolted down (though we’ve seen been advised that it is enough to place it on the screws without actually bolting it down – it was a pain to close the bolts and a pain to open them when we had to take the pump out for thawing). The pump is bolted to an expansion tank.

A ribbed flexible hose runs from the well, through a mechanical filter to keep debris from going into the pump. The pump outlet drops to the floor where it is hooked up to a 3-way flow junction. One (the only one connected at this point) goes to the main house, another is designed for a future connection of the barn and a third is for a water supply in the field.

What We Did Wrong

This is easier to demonstrate with a diagram.

 

The frost-depth in our area is 80cm. When we did the digging we went to somewhere between 100cm and 110cm. We thought that would be enough margin – and it was. However it you look at the diagram you will see that the physical characteristics of the pump bring it to way above the required depth for frost protection. The pump itself sits on top of the expansion tank. Its inlet is at its mid-height (the expansion tank and then some) and its outlet comes out on top and reaches even higher then the pump itself. The result is such that water reaches as close as 40cm from the surface … way too high to be protected from frost.

Once frost gets hold in one component of the system it quickly sucks energy out of the entire system and ice spreads throughout. The entire system froze: the pump, the plumbing next to the pump, the entire pipe running from the bottom of the well to the pump (even though the water in the well has not frozen), and some of the pipe (we don’t know how much) leaving towards the house.

What We Should Have Done

We should have taken into account the pump itself. We should have dug deeper (at least another 50cm) so that the pump inlet would be at just above floor level and inline with the passage-hole of the pipe  from the well into the concrete box. This would have kept everything below frost depth.

 

In addition it would have reduced the need for bending the pipes. The less bends and the softer the bends are – the better flow there will be through the pipes.

Junction Box

A similar problem exists in the junction box – the 2nd concrete box (please excuse image quality).

The main supply is split into two flows – one for unfiltered water in the field, the other for indoor use. Indoor water is passed through a filter (for hard-water deposits – not yet to our satisfaction) and then split into three valves – one of which is currently used and goes to the house. Here most of the plumbing is at floor level – so it should be frost resistant (however since the system has been out of use for a couple of weeks it too has frozen). However the filter is installed again way too high – way into the frost depth risk.

Having the filter indoors would have protected it from frost and would have made it easier to maintain – however we would then filters in other future stuctures where the water supply may go.

What We Will Do

I don’t expect that we will be redigging the bottom of the concrete box – as that may destabilize the concrete itself.

The entire well assembly was taken apart. The pump and plumbing attached to it was brought indoors to thaw.They have since been returned to their place and properly insulated with mineral-wool. A sheet of mineral wool covers the entire pump and will be removed in spring to prevent overheating.

Using rags soaked in hot water I’ve managed to defrost at least the beginning of the supply pipe that exits the well assembly. However since water does not flow out of it I am assuming that it is still frozen deeper inside. I don’t know what to do about that.

The long pipe running from the well has been pulled out and is slowly thawing indoors.

The junction box, after it’s thawed out, will also be insulated with mineral-wool – all the plumbing and the filter.

Pump Doesn’t Pressurize

When the pump is unable to pressurize (when its main valve is shut so that it’s isolated from the supply line) there is a very good chance that the problem is with a no-return valve which should be installed at the end of the pipe that is lowered into the well. This valve keeps the water from flowing back into the well (gravity) when the pump is inactive.

We purchased a special set of pipe with a fitted valve – and the valve failed. When it leaks the pump loses its priming (=when it is initially filled with water until the entire pipe down to the water level is filled with water) and cannot pressurize properly.

I would suggest keeping a spare valve at home  – this seems to be a relatively common problem (I guess they don’t make valves like they used to).

Pipe, Stay

Finally, we had a problem keeping the pipe running into the well properly oriented and in the water – it got twisted (because it was too long) and floated. So, first thing is to get it to the right length – general wisdom seem to be that it should be ~60cm above the floor of the well.

The anchoring solution came from our neighbor – tried and true Romanian villager know-how.

He first destroyed one of our buckets by drilling holes in it. Then he placed a rock in it. The hose itself is tied to the two sides of the bucket. This way the supply pipe will never touch dirt, will always be immersed in water and will always be properly oriented. How cool is that? 🙂

Great joy came when we finally had water flowing from a pipe near the entry of the house 🙂

Next up is getting the water into the house 🙂

Water – Electricity

Despite the irony of the title – electricity was an inevitable next step in the water infrastructure. The basic needs was to get an electric outlet for the pump. However I decided to take it one step further and install additional power outlets that would be available in the fields (so that I wouln’t have to stretch out long extension cords). So I set out to put in power adapters in both the flow junction concrete box and in the pump concrete box.  Though it should have been a straightforward task I did run into a few difficulties and learned a few lessons worth mentioning.

Electric Cable

We purchased a 200 meter roll of three wire cable. I don’t remember the exact specification – but I do remember we chose the one with thicker diameter wires (also more expensive) that were rated for a higher current. I would have wanted to put in more then one supply cable – but the cost was prohibitive.

Much later I learned that there is a 5 wire cable which is usually used for three-phase electric installations. However, I believe it can used as if it were three separate electric cables bound into one. The ground and zero wires are shared and then there are three current supply wires.

I don’t have a specific short-term need for this in mind, however it isn’t every day that you dig a 60 meter long, 1 meter deep trench on your property. So there’s that 🙂

Burying Electric Cable

The cable was buried alongside the water pipe. To protect it we purchased a ribbed plastic tube (2×100 meters length) meant to protect it.

The cable was a perfect fit in the protective tube. As a result, getting the cable into the tube was hard work. Rather then going into the details of how we did it (hint: using a pull-wire and cutting the protective tube into manageable segments) I would suggest getting a more spacious tube. I thought about this when we purchased ours but I thought that a tight fit would offer better protection to the cable. I still think that too large a tube, with too much free space, may collapse under the pressure of the earth and may give out sooner.

Modularity

For the better part of a day I struggled in vain to get the electric-accessories (splitter box and sockets) installed. I wired them together indoors and then headed out to fit them into the concrete walls. Remembers this is work done in a confined underground space. I failed … completely. I couldn’t get is assembled in place.

After a long and mostly fruitless day I realized I had been going about this the hard way. It dawned on me that I could do most of the assembly work inside if I were to simply mount the electric-accessories onto a wood panel and then simply mount that panel on the concretewalls. So, the next day I tried this and it worked like a charm. I predrilled the panels in place and then worked comfortably on them indoors. These are the two panels prepared for installation.

The only electric fitting I had to do underground was to connect the ends of the buried cabled to these boxes. In the image below you can see that I left empty sockets on the left hand side – so all I needed was a screwdriver and a few minutes of work.

Since our electricity infrastructure is outdated and partially improvised this entire supply line is simply plugged into an existing power outlet.

 

Water – Installation Materials

If, like us, you are a complete beginner then figuring out what materials to use that this can be an annoying  obstacle. I was learning about these materials in English and then we (mostly Andreea) had to track them down in Romanian – so it was not just a technical barrier but a language barrier too. What follows are our choices based on the materials that are available here and within our budget limitations. We ended up going with the parts and materials typically used. There are other to choose from … but for all the right and wrong reasons we went with the typical stuff.

Outdoor: HDPE

Above and underground we used 32mm HDPE pipes (in Romanian PEID). This is a robust black pipe of which we purchased a 200 meter roll.  The fact that comes in a roll can be misleading as it is not very flexible – it can go around large corners but it definitely not flexible enough for you to bend to your will.

It was very difficult to lay in the long trench in the ground – as the roll is large and heavy. The  workers who helped took the entire roll to one end and rolled it out – very difficult. In retrospect I think that (a) the rolled pipe should have been placed on the ground at one end  of its path; (b) one person should have rotated the roll while (c) another person pulled the free end out and away from the roll and towards the other end of the path. I think this would have resulted in much less of a struggle. But I haven’t yet had an opportunity to try this 🙂

Easy to use T and corner joints and adapters are available – they are twisted open and closed by hand – you won’t need any tools to hook these up. There are also adapters to make the transition from HDPE to standard metal (aluminum / bronze) plumbing parts. The T and corner joints themselves come in different variations (male, female) which include the adapter connections. Please note that these joints and adapters are not too expensive but not too cheap either. You will need more of them then you think and they can add up to a substantial cost.

The pipe can be cut fairly easily with a hacksaw.

Indoor: PEX-AL-PEX

PEX tubes are a very popular indoor piping system. PEX is a kind of plastic tube. Pex-Al-Pex is a three layer pipe made up of a layer of aluminum sandwiched between two layers of PEX. They can be used for both hot and cold water supply and are fairly easy to work with. There are numerous brands of these  pipes and we chose (based on a recommendation from a professional plumber) to use 20mm “Henco” pipes which are better and easier (more flexible) to work with.

The connectors and adapters are fairly simple to use. The pipes need to be cut straight and clean (either with a specialized cutter or with careful attention using a standard utility knife). Then the end needs to be expanded slightly (either with a specialized tool or with an ad-hoc tool that fits tightly inside the pipe) and after that it is all you need is a wrench to lock it tight. The pipes are flexible and easy to work with.

To the best of my knowledge there are “systems” of PEX tubing which are assembled with pressure joints – this includes joints and adapters into which the pipe is inserted and pressed using a special tool. This is excellent for do-it-yourself work because it creates a perfect seal every time (no leak worries). We still haven’t come across such a system here in Romania. Though, from searching for the images above, it seems that Henco also has a pressure-fitted system – so we will definitely look into that in the future.

PVC

We used 40 mm PVC pipes for collecting and evacuating the water from the house. We have a fairly simple system where all the elements are close together and are collected to one exit point. PVC is pretty cheap and very easy to work with.

The pipe comes in lengths of 1, 2 or 4 meters. One end of the pipe is designed for connecting pipes – it has a slightly wider diameter and holds a plastic washer to achieve a good seal. Two important things to remember about PVC pipe are (1) that the up-stream pipe always goes into the down-stream pipe and (2) since they are usually gravity operated they should be set a 2 degree angle – which is about a 2.5cm drop for every meter of length.

If, for example, you need a half meter pipe you can of course cut it from a longer pipe, however the left over pipe-section will no longer have the connecting/sealing end. However you can work around this – a trick a local plumber taught me. You heat the end of the pipe for a few seconds until is softens and then insert into it another pipe which creates the shape of an adapter end:

Metal Adapters and Valves

The plumbing works included metal joints and accessories. There are quite a few of these and you will discover your way around them and how to use them. I don’t yet know enough about the variety to give a guided tour but there are a few things I can point out.

There are aluminum parts and bronze ones. The bronze ones seem much better in resisting corrosion – the aluminum ones are not very impressive. Yet some parts seem to be available only in aluminum and others only in copper – I don’t know why that is. I am also not sure what are the consequences of coupling them together (which we had to do).

Connecting them takes some effort – you need at least two decent monkey/pipe wrenches and you will need to learn how to work with them. I’m still a beginner. You will need some lining material  (silicon based thread or hemp strings). The most mysterious, to me, aspect about connecting them is when you want to achieve specific orientation. On the one hand they should be tightened all the way to get a good seal yet sometimes that will end up in awkward positions that don’t work out for the connections you want to make. My only solution was to use a good amount of lining material and tighten them as much as possible but not beyond the position in which I wanted them to be (I found that going past the preferred end position and then backing up a bit is a recipe for a leak).

You are going to need valves – probably more then you think – and this, like the HDPE joints and adapters, is going to pile up to a substantial cost. Basically you need valves to give you control of the system when something goes wrong and maintenance is required. The end result of good planning seems to be that  both ends of a pipe are typically controlled by a valve enabling you to isolate the section of pipe between the two valves. This is especially important in long pipes that may contain a large amount of water.

Valves come with different male/female fittings which you can use as you see fit. The long-handled valves are easier to operate HOWEVER they can be more cumbersome to install, especially in more complex assemblies. Remember that as you connect the pieces you will need to rotate them – so they need to be arranged in such a way that you CAN rotate them.  Also, if you purchase a vale with asymmetrical fittings (one side male and the other female) then that limits you in how you can connect it – so you may find yourself with a valve oriented the wrong way. This may sound stupidly obvious … but I put myself into a few tight corners by choosing the wrong kind of valve. So I’ve said what I have to say 🙂

 

Building an Earthship in a Cold Climate? STOP

… and read the book Passive Annual Heat Storage – Improving the Design of Earth Shelters by John Hait.

  • Should Earthships be insulated? Yes (but not in the obvious way it’s being done today).
  • Should Earthship floors be insulated? No.
  • Can an Earthship provide a comfortable (21c) climate using passive means during the winter season in a cold climate? Yes.
  • Can heat be collected and stored during the summer for a winter with very little (mostly cloudy) passive solar gain? Yes.
  • Can an Earthship be properly ventilated without having to sacrifice precious heat? Yes.
  • Are skylights a must? No.
  • Is the corridor wall (introduced systemically in Global Model) Earthships required in cold climate? Not necessarily.
  • Can an Earthsip be built in clay-rich expansive soil? Yes, if the soil kept dry.

When it comes to cold (moist and frozen) climates like ours here in Romania, there are quite a few things that felt, to me, incomplete, missing or even wrong in Earthship design (including the latest and greatest Global Model). To me what was missing most is the lack of explanations of how things work and why they are designed the way they are. I could not find satisfying answers in any of Michael Reynolds’ Earthship books (Earthships have evolved way beyond their description in the original Earthship books) nor online in many of the documented builds and open discussions about Earthships.

Then a few days ago I published this post about ventilation problems in an Earthship and began to compose my thoughts for a follow-up post. The solution seemed to come in the form of earth-tubes. The first resources I came across (pretty much as they were presented in the search results) were:

  •  Wikipedia – which provided basic technical information.
  • The Natural Home – which provided a convincing argument for earth tubes.
  • BuildItSolar – which raised some questions and left me with some doubts.

Luckily I stubbornly pressed through a few more pages of superficial search results and on the 3rd or 4th page found an article by John Hait inaptly titled Umbrella Home. The article blew me away. I ordered the book and couldn’t put it down – I read it word for word in just over a day and will be re-reading many parts of it again.

The book truly lives up to its subtitle “improving the design of earth shelters”. Not only does it open a door to a much deeper understanding of earth-tubes but to do so it introduces a fantastic concept of a large insulating/blanket which surrounds an earth-sheltered house in which earth-tubes can really come to life.

The core idea (backed up by accessible explanations and practical research) is to create an insulated and water-proof blanket that encompasses the house and a large area (~6 meters) around it (which can be achieved with more or less the same amount of insulation materials used for standard wall insulation).

This insulated umbrella creates a large body of earth which is dry and functions as a huge thermal battery attached to the house. The house itself acts as a solar collector to slowly charge the immense thermal battery during summer. Then, during winter that battery slowly discharges heat back into the house.

Earth tubes are used with this umbrella (in a way that could not achieved without the umbrella) to passively generate both ventilation and temperature regulation (cooling & warming) of the house. Because the earth-tubes run through the thermal battery surrounding the house they work as a super-efficient heat exchange system. A passive air-conditioning AND heat-exchange system that is simple and affordable.

 

As a cherry on top  – imagine running an uninsulated water supply pipe under the umbrella and having water preheated to 21 degress (celsius) during winter  (cold water supply has to be insulated under the umbrella). As someone who washes dishes with freezing-cold water (unless I fire up the wood boiler) I am watering at the mouth at the thought of washing dishes with passively heated (no additional energy expense or effort) warm water. Not to mention energy savings in heating bathing water.

This may cause a problem with Earthships that include rain-water harvesting stored in buried cisterns. The cisterns, if buried close to the house, under the umbrella will become a source of warm water. Cold water would have to be cooled somehow and I don’t know what effects this may have on the stored water. Since we’ve decided to forgo rainwater harvesting and put in a green-roof this is not a problem for us.

If you’ve already built an Earthship in a cold climate and it isn’t functioning as well as you thought it would I believe that at least some of the measures described in the book can be added to your Earthship to make it a much better home.

I don’t recommend trying to implement this from the basic information in the article. I STRONGLY recommend reading the book word for word. It is educating and empowering and fun to read.

I am now (again) heading back to the drawing board to revisit and rethink our house design. I feel I know better now and I am grateful to John Hait for his work and for making it available to others.

Earthships and Ventilation in Cold Climates – Problem?

Ventilation and air quality is one of the last and most problematic issues I’m left with in regard to Earthships in cold climates. Cold climate is what I’ve experienced in a mild Romanian winter which includes snow cover, continuous (many weeks if not months) subzero temperatures and no sunshine (passive solar gain) for two week stretches.

To avoid confusion (as I have encountered it myself in trying to figure out this issue) let me re-iterate: the problem I am trying to outline here is not heat but ventilation – the removal of stale air and it’s replacement with fresh air. There is no question in my mind that no matter how efficient a properly insulated Earthship can be, in our Romanian climate, it will require additional heating. However heat and it’s origin does effect the flow of air throughout the house.

In this post I will try to outline what I’ve been able to figure out so far. The bottom line will be that in cold climates there is a ventilation problem. I hope this post provokes further input and conversation through comments. I would especially love to hear from people who have lived in Earthships in cold climates and their experience of ventilation and air-quality. Then, in a separate follow-up post I will try to present what seems to me like a potential passive, energy efficient ventilation solution.

Classic Earthship

The classic Earthship ventilation theory is simple and straightforward. Fresh cool air enters from the operable windows on the front face. This air is heated by solar gain, warm air rises and escapes from the skylight resulting in a continuous flow of fresh air through the living space.

The ventilation problem is already present in this simple model. What happens when it’s so cold that operables and skylights (both covered by snow) are kept close to keep heat in (and snow out). To my understanding there is no air flow.

 The only way to get fresh air in and stale air out is to let the cold in. Earthship theory would say that is not a problem because the thermal mass of the house contains enough warmth to compensate for coolth that comes in through the openings. In our climate I don’t think will hold true. I think we will have to heat the house in addition to water solar gain (hopefully much less then a house built above ground) and ventilating would entail precious heat loss.

Global Model Earthships

The Global Modal Earthships make two distinct changes to the elements of ventilation (actually there is a 3rd which I will address separately, see earth-tubes below). The first is the introduction of the corridor wall which separates the living spaces from the greenhouse. The second is the skylight over the greenhouse which comes INSTEAD of a skylight in each living space (I wasn’t sure about this until I encountered this video from Earthship Biotecture). In this configuration the greenhouse has been described as an air-lock that supposedly provides better climatic control by isolating and containing variations between it and the living space.

 There are now two ventilation circuits in the house. The first is between the outside and the greenhouse and the second between the greenhouse and the living spaces. The ventilation loop between the outside and the greenhouse is obvious and is similar to the classic Earthship approach.

I have some doubts how well the ventilation loop between the greenhouse and living space will work. As I understand it, if passive solar gain is the main source of heat then the greenhouse will always be warmer then the living space. This means that there may not be much flow from within the living space (cooler and heavier air) to the greenhouse (the already warmer and lighter air). It seems to me that the flow in the greenhouse may over-power the flow from within the room. This may be effected/controlled by alternating openings (eg: first ventilating the greenhouse, then closing it and ventilating the living spaces) and height positioning of the ventilation passages between the corridor and living spaces.

As with the classic greenhouse I do not see any potential for passive ventilation on cold cloudy winter days.

When a source of heat is added inside the living space and the hot inside it becomes warmer then the greenhouse – there can be a ventilating flow between the two spaces (and of course heat will be lost from the living space to the greenhouse).

If, in addition to the heat source, the front operables and skylight are opened then there may be some draw of fresh air from the greenhouse to the living space (and of course heat will be lost from the living space to the greenhouse and then quickly to the outside).

So, it seems that any ventilation will come at the expense of precious heat.

Earth-tubes

Global model Earthships introduce another element they call “Cooling Tubes”. These are tubes that are buried in the ground (~20 feet) behind the house and penetrate the rear wall.

They are intended to provide natural cooling. Warm air in the greenhouse is released through the skylight this creates a draw pulled in through the cooling-tubes. Warm air is drawn into the tubes from the outside, loses heat to the ground in which the tubes are buried and arrives cooler into the house.

This solution addresses ventilation in a hot climate, it does not address ventilation in a cold climate. However, I do believe it points in the right direction. More on that in an upcoming post.