One forgets, when you are deep into a project like this one, that most people are unaware of such concepts as “sustainable” or “green” building, have never heard of building houses out of straw bale, and are simply used to the way things are and have evolved over the decades: We don’t live in caves, we live in houses.  And that is a tremendous improvement, but far from perfect.

Recently at a dinner party the fellow to my left was the latest of many who had never encountered straw bale construction but who seemed interested in the whole concept.  I thought I would take this opportunity to describe better the components to our project and what features we will have that we consider “green” -- or whatever term you like.

Let me also describe what we are trying not to do: create the normal modern American house.  A comparison of approaches:

Insulation in normal house: Ordinary stick frame houses with their minimal few inches of fiberglass insulation are not designed with energy efficiency in mind.  Not to go into too much detail, but “normal” houses are not well sealed against the elements, especially the wind, and the insulation used is not sufficient to keep the house either warm or cold.  Rather one burns fossil fuels to heat the home in winter, or runs some kind of cooling system to cool off in summer.   These homes are also not well sealed against the wind and the insulative properties of fiberglass falls precipitously in windy conditions.

Insulation in our house: A straw bale home, with its thick, thick walls of highly compacted straw is highly insulated.  And assuming one puts in highly insulated windows – as we plan to – the house becomes a thermos, helping to keep the interior temperature constant.  There are fewer cracks for wind to penetrate and while the insulation is not as good as a deep cave or an earthship, it’s hard to beat.

Thermal Mass: Is an additional concept our home will take advantage of to maintain the interior temperature of the house.  We obtain thermal mass in the case of this house by having the interior walls made of stone or adobe.  While there will be a couple of interior frame walls, the vast majority will provide thermal mass, which “is any mass that absorbs and stores heat during sunny periods when the heat is not desirable in the living space of a building, and then releases the heat during overcast periods or during the night, when the heat is desirable. The same can be said for not absorbing heat during hot periods of weather. The internal mass remains at a lower temperature than outside keeping the occupants at a more comfortable temperature. Cooling the internal mass can then be achieved by ventilation during cooler periods, typically at night.”

Some of our walls will be made of stone – though in this case they will be gabion walls.  A gabion wall is one in which the stone is held up by a wire mesh, without mortar.  The stone will come directly from our property, saving money as well as the environmental costs of shipping rock from some other rocky place.  It will also save time from mortaring, although the collection will take some effort – and this is something I will be doing largely myself.  We won’t be using mortar, saving a small amount of cement. 

Others of the walls will be adobe, which also has good mass properties.  In addition to the walls, our floors will be stained concrete which will also provide some thermal mass.

Ordinary houses typically do not bother with thermal mass at all.  Often wood or carpeted floors, which have none of these properties, are used. 

Orientation: Most houses are built with two thoughts about how they are oriented: towards the street, or towards a view.  Our house will be oriented so that the south face will have windows that will collect the winter Sun’s energy (heating the interior air and thermal mass) but with overhangs that block out the Sun’s rays during the rest of the year.  This passive solar heating will go a long way to heat the house in winter.  One of the fellows we are working with believes that the house will be able to maintain a fairly constant temperature of 70-74 degrees with additional heating only needed rarely. 

When you think about how simple this concept is you have to wonder why it is not more commonly employed.  We have neighbors to have a house in which some of the rooms that have a south facing wall and that overheat in summer.  In the rest of the country people just use more air conditioning (what we here call refrigerated air) to combat the problem while here our swamp coolers simply fail to make much of a difference.  Our neighbors have planted trees that will go a long way to ameliorate the problem, but one wonders why the design allowed for so much trouble to begin with.

We used to live in a house in Albuquerque with a huge window that offered an Easterly look at the Sandia Mountains.  Nice, but the summer Sun heated the room into a furnace in the early morning causing us to leave the blinds closed for half of the year.

Electricity: Our house is going to be entirely off the grid and we will be using solar (photovoltaic) panels to convert sunlight into electricity.  This entails a large up front cost, but over time the free electricity will pay for the system.  We will also not be responsible for the burning of any fossil fuel.  Obviously normal houses are on the grid and are powered by the usual suspects.

Heat, Hot Water, Heat for cooking:  As mentioned, we hope to need only limited additional heat for the house.  Code requires a heating system and we will install radiant floor heat.  We considered having this be powered by the Sun as well, but have discovered that such a system might not be efficient enough in the hills outside of Santa Fe.  Instead we will most likely have a small boiler heated by propane.  With any luck we won’t need to use it all that much.  We will need the propane on site in any event since that’s what we will be using for the stove.

As for a hot water system, we may have some of that heated by the sun, but with an additional “on demand” (tankless) hot water heater for spot use.  Most homes have a large tank that is heated all the time, whether the water is in use or not.  We will have a system whereby the water is heated only when needed.  We’ve used these at Susan’s Uncle’s house in Germany and they are great.

Most homes still employ the big, hot tank, often housed in the garage or in a small, poorly insulated room that causes the thing to use more energy to heat – all the time.

Walls, and wall coverings:  Modern American homes have mostly frame walls with gypsum-based wallboard nailed onto wooded studs.  Typically these walls have no insulation within them since they are inside already, and they have no thermal mass.  The walls are then plastered over and painted with a modern latex paint. 

The vast majority of our walls will be straw, adobe or stone (as mentioned above).  The straw and adobe will be plastered with an earth plaster (in the case of the strawbales, with clay, sand and straw) and with the adobe; clay, sand and perhaps lime.  For the few frame walls (bathrooms, laundry) we will paint them with a wheat-paste based paint that we will cook on our own stove.  The process is surprisingly simple: you heat wheat with water until you get a paste and then you add some clay or other colorful dust to the mix to make it pretty.  While labor intensive, it is very cheap, has no odor, and is so environmentally friendly you can eat it.

Water:  Our home will be located in the high desserts outside of Santa Fe, New Mexico so water conservation is a top priority.  The first thing we plan to incorporate into the house design is a rain catchment system in which we will capture all the rain that falls on the roof and divert it into a cistern for later use.  We are looking at various filtering options – even considering installing one designed for earthships – so that the water can be used for as many different things as possible.  My personal hope is that we can use the water for all indoor needs, supplementing it with well water only when needed.  If local codes and all that prohibit some uses, then we will minimally use it for toilets and any outside watering.

It boggles my mind that so few houses in New Mexico have any sort of water reclamation system.  You might think that here in New Mexico there is not enough rainfall to make much of a difference.  But a small 1,500 sq ft roof area collects 900 gallons of water for every inch of rain that falls on it.  Our roof, though covering a 1,450 sq ft house will catch over a thousand gallons per inch (given the pitch of the roof) and we will also have our garage attached to the system adding another 400-500 gallons (per inch) every time it rains.  (Every outbuilding that we add will also be tied in one way or another.)  

Assuming the average home has 2,200 sq ft of roof and New Mexico averages 10 inches of rain a year (sometimes it's less, but I’ve seen averages of 9-11 inches quoted often) then the average rain collection would be 13,200 gallons.  Of course this collection is very seasonal and heaviest during monsoon season, but still the water could be used.

We will also install a gray water system so that all of the water used in the house, aside from the toilet itself, can be used for a second time.  This will take care of all of the outside watering needs since we will be using primarily xeriscaping outside. 

So ultimately what we are planning to do is build a house that uses the least amount energy to heat and cool, one that will passively accomplish most of those tasks on its own.  A house that is built of an many recycled or otherwise wasted materials as possible.  That will be built using the least amount of chemicals imaginable and that will be beautiful in its simplicity, its efficiency and by being in keeping with the surrounding landscape.