What's the best way of getting an eco-friendly off-grid house?

Question

My partner and I have been considering what the different options are for buying properties in the UK. We are interested in at least 1 acre of land, plus a house of 50-70 square meters minimum.

We would like to implement as many sustainable strategies as possible, ideally being nearly off-grid, with solar panels, rainwater storage, grey water recycling, humanure / methane tank toilets, ventilation based on good design, etc.

All these requirements in terms of energy management and design imply that buying a new house is probably not the best option, because we rarely find systems like this in houses which are for sale.

Therefore I had a look around, and I found out the following.

Option 1 - buy land and then go for:

• Earthships don't seem to be viable yet, there are only a few in the UK and none of them have residential permissions. These would be great both in terms of size, sustainability and price.

• Tiny Houses are too small for us, unless there is someone who produces tiny houses of more than 5 m^2. The price is optimal though.

• Hanse House? Any advice?

Option 2 - Buy a house with land.

• Buying old houses/cottages and making them eco-friendly is too expensive, as I understand from a quick search online.

• Buying houses from people and then modifying everything to make them eco-friendly is outrageously expensive, because the property market in the UK is currently crazy.

Do any of you people have experience with self-building or refurbishing a house to make it eco-friendly? What are the possible routes into this?

Answer 1

I think you're right that building your own is likely to be necessary (we're in the same position). What I've discovered in Australia is broadly applicable in the global north, so:

• An earthship can't be sustainable, and is not designed to be sustainable - they are about being self-contained within a very narrow definition of the term. They rely on free labour from outsiders for the build. Lots and lots of free labour. If you have to pay for the labour, very few people can afford the house.

• The TinyHouse movement is as much about not building more than you need as about going tiny, and everyone can do that. I have used some of their ideas to adjust my expectations, but I'm also that way inclined to start with, so our current plans are under 60m² habitable space for a couple with a spare bedroom. We're using a "dutch bed" or bed-in-cupboard with a separate office/computer room, for example, rather than a "master bedroom", so one of us can sleep while the other works/plays.

• the Hanse House looks like a bigger version of what I've ended up wanting. Or more accurately, I want more workshop space and less single-purpose interior space, so I've made different design choices. But broadly, yes, design a small house, add a spare room, and build that. The spare room will end up being used, so put it in when you build - they're expensive to add later.

• refitting a run-down house can be done, but the usual reason is so that a DIY builder can avoid needing a construction loan and to reduce the number of permits required (and the property can be inhabited throughout the build... note that I didn't say "habitable", just "inhabited").

• buying an existing house is best done so you can rent it out and live in the new granny-flat you build on the block of land. It's called "in-fill development" and many local governments are keen on it.

I have done a bunch of research locally, and ended up wanting to use SIPS purely for the ease of getting a passivhaus standard build (although likely not paying for the certification). That standard is hard to reach with conventional build processes, not least because fixing problems and re-attempting certification can be insanely expensive and require compromising the structure or philosophy (you start with a nice green insulation material, but then you discover air leaks and either tear half the house down or re-seal with sprayfoam... as one example).

It is worth paying a builder who has done this before just to save you a great deal of "first time woes", even if that means getting someone from across the country. Ideally you'll find a local who wants to get into it, and they will work with an existing builder from somewhere else. We may yet end up using a Tasmanian company in Sydney because they want to expand this way. The benefit is they're likely to give you a discount/better service because they want you to be their demonstration and ideally a bit of a show home.

I suggest being open to your local experts, too. It doesn't matter if you have chosen the best technology/product in the world if you can't get it installed and working properly. Much better to go with what the local green technician likes, because they will also likely know about the maintenance and warranty issues. We contacted a company in another state who sell a combined solar hot water + electricity installation service and asked them, they recommended a couple of local installers, and one of them looked at my idea and said "cheaper and simpler to have separate hot water and PV"... and convinced me. He does do the combined product, but only on demand and only with a five year warranty. Apparently after 7-10 years they fall apart and can't be repaired. You will have different products with different problems... ask the local expert.

Note that any expert is almost certain to tell you that off-grid is an expensive, silly idea. It's anti-social so it fails that leg of the sustainability test, but it also means paying for a great deal of capacity that you will very rarely use. Much better in many ways to go grid-optional with 2-10 days of runtime depending on the season. You may also struggle to get off-grid sewer treatment approved at all for a single dwelling (and it will be expensive, in NSW you're looking at more than $1000/quarter for testing and certification for the smallest system because they expect that "smallest system" will be a subdivision).

I found our local "Alternative Technology Association (ATA)" very useful for this stuff. I suggest trying to find something similar in the UK.

Answer 2

I suggest that you question some of your assumptions.

Difficulties of off-grid.

Off-grid is HARD, and generally isn't worth it unless you are a long ways from the power lines. If you are looking at one acre, you probably aren't that far away.

Let's look at what goes into off grid:

Electricity

Grid connected solar means you size your PV to provide about as much power per year as you use. Off grid means you size it provide enough power to run essentials during the darkest, coldest time of the year. At my latitude and climate (Central Alberta -- about equivalent to Edinburgh) that worked out to be between 2 and 2.5 times the year round grid. For me, on a small farm I needed 20 KW installed capacity.

For off grid, you need to store this. Current thinking is you need to store 5 days power, but you really need to model this with your climate, and determine how many 'brown out' or 'fire up the generator' days per year you will tolerate. Battery tech is getting better and cheaper, but for me I figured I needed to store 80 kWh. PV arrays need to be kept clean. It's amazing how much power a big blob of seagull poop costs you.

Factor your batteries into it. Lead acid typically need to be replaced every 3-5 years, assuming an average of 30% discharge on a daily cycle. This can be increased with appropriate battery maintenance. Good chargers, inverters, and battery monitors. A controlled environment to keep them in. (Can't just be stuffed in a corner of the garage.)

You lose a fair bit of energy doing the DC->Battery Charger -> Inverter, so there is a win in using DC for your big power loads, and having smart enough controllers that you can tap power directly off the charger.

Grid connected solar,with surplus feeding the grid makes much more sense economically, and can be worth doing even if you only get credit on your bill for the surplus. (In some areas they have to buy the power back at the maximum price they are paying anyone.)

Water

Here, most 1 acre properties would be on city water. Going off grid for water either means being a fanatic about rain collection, or having a well or spring or creek, or trucking it in.

Heat

I figure you can get 1 cord of firewood per acre of woods sustainably. I've done it here for 20 years and the woods look pretty much like they always have.

Good house design will reduce your heating needs, and in much of Great Britain may eliminate space heating. Domestic hot water may still be an issue. The key for that is large storage tanks to match the time of hot water generation to times of use. Where a 30 gallon (120 liter) tank is suitable for most households that use electric or gas heaters, if you are heating hot water with the sun, I'd suggest putting in at least 200 gallons. If you are grid connected it may make more sense to have a smaller electric tank, and more PV cells.

You can truck in propane.

Sewage

There are various ways to dispose of waste, but here you can't use a septic field on properties under 10 acres. The closest you can come to off grid is to use composting toilets, reuse grey water in the garden, and try to reduce what goes into the pump out tank. I doubt you will be able to get permits to build without some provision for sewage disposal. Here, composting toilets aren't popular with building inspectors, and grey water usage is illegal.

Data

We're connected to the world net. Sure you can use your phone's data plan, but check how much data you use per month. For lots of us a fixed connection is worth it. We're connected via WiLAN to the world. Setting up that connection was pricey because we needed a 70 foot tower.

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Building your own house.

• Start with a trailer or RV (caravan, I think you call them) You can often get these dirt cheap used, and it gives you a place that is warm and dry while building.

• Consider leichtlehm (light straw) Think of packing straw into forms that has been dampened with a clay/water slurry. It's finished with a coat of plaster.

Advantages: You start by building a pole frame or timber frame house. YOu get the roof on first. NOW you have a dry place to work -- at least when the wind isn't blowing. It goes up reasonably fast and the weights are fairly easy.

Note that leichtlehm is the basic technique used in Tudor times -- hence the dark beams with white fill, so if you get good at it, you may be able to work as a restorer. Flip that around: Work for a restorer, to learn how to do it right.

• Straw bale construction is also viable. No frame needed for a single story building. Typical building envelope costs are on par to slightly higher than convention construction, but since more of it is doable yourself, you can pay with sweat instead of cash. Strawbale can also be done as infill on a pole barn house, which is worth doing if you have a rainy climate, or are skeptical about getting the roof on in a single dry season.

• Cob is suitable for England's climate. A mix of mud and straw, it insulates better than stone, but not by a lot.

With any alternative building system, get the local building people on side first -- before you buy the land. Some are much more open to innovation than others. You may find that by being in another jurisdiction you have less hidebound building inspector.

1 acre isn't really enough for food independence. Raising enough food is difficult, and your neighbours may object to chickens and pigs. You may find a better deal 15 minutes further from civilization. The usual trade off is commute time versus land size. Here, (Alberta, Canada) 45 minutes is the magic number. We bought 80 acres and 2500 square feet for the half of what we'd have paid for a similar size house on a fractional acre lot in Edmonton.

Get your septic in early. You can run the caravan's waste to it.

Spend time designing your house to fit your climate.

Overbuild the air circulation system. A house that depends mostly on wood heater and/or solar gain for heating/ open windows for cooling is going to have heat or coolth in the wrong places a lot of the time. Having larger ducts, and bigger fans allows you to move warmth where it's needed, or bring a flood of cool air in during the night. Open concept living spaces can just use a ceiling fan -- about 12 watts on slow speed. Bedrooms can be considerably chillier than main living rooms. Monitor humidity though. High humidity can lead to mildew. Look at mildew resistant paint.

If you are going off grid or near off grid, there are other changes:

• Plan for multiple electrical systems. Lots of caravan equipment is designed to work on 24v DC. Anything you can use straight off the battery avoids the inverter. In some cases you can run it directly from the PV cells, but this requires some smart circuitry.

• You aren't going to get it right the first time, so make ALL your utilities accessible. Put wiring in raceways disguised as chair rails. Where surface mount wiring isn't workable, put in conduit so 6 years from now you can fish another wire pair to the living room. Wall plumbing has a closet on the other side with a removable panel. Drains are accessible their full length, and have lots of cleanout ports. Keep the grey water separate from the black water. You can use the greywater in the garden, or get two uses once as grey, once as black.

• Keep the roof simple. Simple roofs (No valleys) are less likely to leak, and have simpler setups for collecting rain water.

• A metal roof puts less junk than a asphalt shingle roof into your water.

• Make the roof bigger than the house. Roof is fairly cheap, especially if it's simple. It keeps water off the walls, and provides storage for wood, tools, empty canning jars. It's also a place for the kids when it's raining. Lots of farm jobs are more pleasant if you can be outside, but dry.

• Plan your house for using wood/peat for heat in colder months.

Do your homework. Become the local expert.

Answer 3

We would like to implement as many sustainable strategies as possible, ideally being nearly off-grid, with solar panels, rainwater storage, grey water recycling, humanure / methane tank toilets, ventilation based on good design, etc.

Forget it.

For example, my house (105 square meters) has perhaps 3500 kWh of electricity used and 13000 kWh of heat used per year. This isn't some load that varies in perfect synchrony with the sun as the sun goes up and down, but it's a continuous load with electricity use peaking after I get home from work, and with heat use peaking when it's cold. When it's cold, the Finnish winter has so little sunshine that solar heating would be a bit tricky. I'm not saying it's impossible but the expenses of collecting enough solar heat would be far more than buying the electricity would be in the first place.

The 13000 kWh of heat when produced with a heat pump would consume about 3700 kWh of electricity. So the total electricity usage would be around 7200 kWh.

In the area where I live, a company producing nuclear power and hydropower trades for around 18 euros per share. One share is enough to produce 76 kWh per year of CO₂-free electricity. So, to produce 7200 kWh of electricity per year would need 95 shares, costing 1710 euros. (This 76 kWh per share is the clean generation; currently the company has some CO₂-emitting production too that will be surely shut down in no time so I didn't count it in the figure.)

Show me the system of solar heat collectors, solar panels, inverters, battery chargers and batteries that can produce the electricity and heat for less than 1710 euros!

The cleanest power comes from the electricity grid of the future. The current grid still has some dirty power that will be shut down according to the climate agreements. The way to achieve as much environmental benefit as possible for a given amount of money is to invest them to clean grid-scale energy production, not on producing batteries that requires huge amounts of resources and thus has a big ecological footprint.

Answer 4

Building a house often involves paying a contractor $30000 to build a heavy concrete-block foundation.

Instead build your own foundation by sticking a piece of 304L in a wet-pour concrete footing.

For instance, consider a bird's-eye-view of a 304L L-angle, at 0.100 to 0.120 thickness, that has legs pointing North and West. Then take a 304L channel with legs pointing East. Bolt the channel to the North-pointing leg of the L-angle but have the channel cut shorter such that a floor-joist can sit on the channel and bolt to the side of the L-angle. However, have the width of the channel such that a wall-stud can sit beside the floor-joist. Now put a second wall-stud on top of the floor joist and bolt it in place.

Then as the two wall-studs reach the ceiling-joist one wall-stud is cut shorter such that the ceiling joist can sit on one stud and bolt to the side of the other stud. Of course the opposite side of the ceiling-joist and floor-joist is also built and the entire house bolts together.

But only use 18-8 nuts, bolts, and washers when touching the 304L. Galvanized nuts, bolts, and washers are okay elsewhere but zinc-planted nuts, bolts, and washers are not okay.

Now since the house has two wall-studs at each stud location, consider using even rough cedar lumber. Or inexpensive white-pine is okay if bugs are not a worry. In fact floor-joists can be stacked in position if an extra-size of floor-joist is needed.

If the foundation has high reaches, then instead two wall-studs can rise from the 304L foundation such that one wall-stud is cut shorter for the floor-joist to sit on. Then a bolted wall-stud piece is fitted between floor-joist and ceiling joist. Of course use wall-studs with taller cross-sections for the floor-joist support.

Now a bolted blocking is required near the tops of the wall-studs. Use 0.100 to 0.120 thickness galvanized brackets for the bolted blocking.

Finally, all the concrete that the house needs is for simple small footings at floor-joist supports. Also, the crawl-space house can add systems at any time.

Additional notes, construction of the 304L foundation requires a metal-cutting bandsaw and power-drills for drilling holes. Also, the 304L should be bought wholesale in twenty-foot lengths. Foundation layout and height is required. Oh, the foot of each 304L support, as set in a wet-pour concrete footing, should have a 304L plate on the bottom.