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Prefab Green Home Net Zero Off Grid Systems Post #3

An astute reader took me to task yesterday regarding our prefab net zero green home, the casa ti. : )

Correctly, they observed,
Just read the #2 on systems. It brings up what I was saying - where the heck are you going to put two 80 gallon water tanks? The plans shown on-line do not have space for 1 much less 2 water tanks. Are you putting them outside? Where are the PEX tubes for the floor terminated (meaning where do they come out of the concrete? In a closet somewhere or outside the house)? You'll need a pump for each loop and they take up a fair amount of space also (about the size of a coffee machine mounted on the wall).

Handsome Husband (who is responsible for our prefab’s off grid / net zero systems) responds:

“The green building architect David Day's prefab floor plan shows what I am using as a system cabinet as kitchen storage.

Here is a detailed view of the cabinet that houses our net zero, off grid systems.

We are keeping the footprint the same but are converting storage to system space to accommodate the prefab house’s added solar tanks and radiant heat needs.

Space needs vary between different heating and DHW solutions and in our case where we are off grid we are dedicating more space to the system needs than others might. 

But then again, we are going off grid all the way and are willing to create that lost storage in furniture instead.

I will post the corresponding system specs over the next few days once I have transferred them to digital media.”

So, like many other consumers, we took the prefab architect’s suggested floor plan for the prefab house kit and modified it for our own needs with our contractor.

Not only did we move the kitchen from the west to the center of the south room, but we also adjusted the green building architect’s suggested dimensions for closet space to accommodate our net zero off grid needs.

Here are some pictures so you can see how easy this is to do with your contractor as the bedroom dimensions are currently just laid out / framed:


Here is a link to the green building architect’s suggested floor plan of the prefab so you can see what the architect envisions, which you can compare with what we’ve done as our own prefab house kit consumers…

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Prefab Green Home Contractor Meeting Rescheduled.

I have just rescheduled the meeting (previously cancelled due to snow last week) with our contractor in the prefab green home for Saturday.

Of course, the next comment from my coworker, Amy, was, "Did you hear they're calling for more snow?"

We. Shall. See.

In the meantime, we had Gwendolyn & Damon Pearson over for dinner last night.  You may already be aware of Damon Pearson, our Princeton-trained architect, partner in the fabulous design and fabrication firm, Tektonics, and designer of our sister modern prefab site, Green Cabin Kits

We have some upcoming big news on those prefab green homes – we are now modifying them to be fabricated like the rest of our prefab house kits (modern prefab at Green Modern Kits, and prefab cottages at Green Cottage Kits) – already passive solar, and built with SIPs, the prefab cabins will now be fabricated at plants throughout the United States, not just Tektonics.  We will be publishing those new designs in January.

I am also adding new voices to Green Cabin Kits – the Pearsons.

Gwendolyn will provide a counter point to the industrial and prefab design / technical voice that Damon, as the architect, will add.  Oh, she will be off topic (and likely off color) – but leads such an interesting life as an environmental educator for a national nonprofit that I want to share her daily musings with the world.  There were *so* many tales told over the table last evening it certainly could provide fodder for months of postings!  (Ask her about the bucket of eels…)

Of course, when there was a wane in conversation, we always had the dogs to entertain us… (see below video…)

That’s all I can say for now… in the meantime, I hope you enjoy the food pics from dinners this week!

And more exciting news on all our prefab house kits coming after the New Year.


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Prefab Green Home Systems Post #2: The Heat For Our Net Zero Energy SIPs House Kit

We have certainly been thinking about heat for our prefab net zero off grid house this week.
We had one of the biggest snowstorms in recent memory begin Friday, and on Sunday we drove slowly, carefully to vacation in West Virginia.

We love history, old architecture, eclectic design, and natural, local beauty.*
So where to vacation? The Greenbrier.
Experiencing what still works in a resort founded in 1778 allowed us to observe and apply timeless elements to our own modern prefab net zero house, today. We have the prefab advantage of highly energy efficient structural insulated panels, passive solar design, radiant heat in the polished concrete floors.  What resonated with me was the importance of cozy cottage comfort after a brisk hike in the crystalline air; wet freezing children shedding thick layers of soppy, stiff, half-frozen crunchy clothes...

As you drive through the mountains today, you are aware of how dangerous weather can be - and imagine the perilous journeys over centuries, even just decades ago with no shelter, no dry welcoming  warmth, no means of communicating for help.

Still in this day and age, the roads can be treacherous.

We took our time.
My northern German husband who went to graduate school an hour away from the Alps was surprised and intimidated by the road conditions we encountered. 

Finally, we arrived...
We knew we had a cottage... but didn't expect... THE Cottage.

What we took back with us, after a glorious few days sledding and hiking in the elements yet always within reach of immediate creature comforts was... the admittance that in rural areas, despite the coolio latest technology that allows passive solar, net zero comfort... you need to also always think about the dire situations...
Y'know, Dire Straits...

So... this is about survival.
Not in a fear-mongering way. In a practical, affordable, positive way, as a boost to our otherwise comfortable solar systems, our prefab's passive solar design and energy efficient, tight insulation; to ensure that we're also really ready for rugged, rural, sometimes desolate and emergency conditions.

On cue, as I continued my ongoing reading journey of The Moomins with my children tonight, Snufkin ran up into a similar scenario with no less than twenty four little woodies he had somehow acquired after his revenge on The Park Keeper. Tired, cold, wet, hungry, they arrived at a cottage. Inside: a wood stove, and a pot of beans. Soon their wet cold clothes were hung, empty bellies filled, and...
Hurrah, they were saved.
And this is what I think:

Honeychile, there's never harm in good back up. In fact, you rely upon it. 

* Fer you astute history and enviro business buffs, the whole Coal Country experience is something to be addressed in a separate post, in itself a whole different experience... wow. More soon, in a whole different post focusing on economy and scale of local industry... industries.

Here is... The Heating Post.
(Schematics later, here begins Handsome Husband's thoughts:)

Space Heating and Domestic Hot Water (DHW) For The off-grid zero energy prefab home:

We have been planning and realizing our prefab off grid net zero SIPs house for 3 years now. The actual construction began a year ago. Although the prefab house kit was erected and sealed in with windows, doors, etc. within a week, one of the factors leading to our own extremely long period of construction once the exterior was weather-tight was the search for a solution to our heating needs that fits our building structure, geography and long-term goals. (House kit consumers could certainly have finished the interior long before we have with our own prefab house kit!)

To better understand the amount of choices let’s compare the issue to off-grid power: You can calculate how much power you need (or want), how many days of power supply you want to be able to store in your battery bank and whether you want back up power. All that is left then is choosing from solar, wind or water as your primary power source – a fairly well understood calculation.

For hot water and space heating the options are far greater:

Heat Collection
We can collect heat from the sun via solar hot water collectors (flat plate or evacuated tube designs) or take advantage of the warmer temperature in the ground below our dwellings (geothermal heat).

Heat Storage
We can store the collected heat in tanks filled with liquids or bunkers filled with sand. Either needs to be insulated to preserve the heat until we need it.

Heat Delivery
We can heat our spaces by transferring the stored heat to warm air or warm liquid.

Backup Options
Backup really refers to the conventional heating system and obviously should be used as little as possible. This presents the biggest challenge as we want to avoid it at all means but still have to account for it.

The solution you select depends on your goals:

Freeze Protection
We need to protect our homes from catastrophic failure.

We need to determine what level of comfort we expect if freeze protection is covered. This is a personal choice. One may state “I am fine with not taking hot showers” or “I will put on a sweater or two” if my heat storage is depleted or one may say “I want to have a choice to take a hot shower or maintain a warm temperature”.

In our case we want to be able to make the choice. This allows us to ask of the design to provide us with comfort when the system is depleted.

Our Prefab's Passive Solar Design
During a birthday party for one of our son’s classmates I spoke to the father about the casa ti. He installs heating systems for a living. I shared our observation that the passive solar architecture in conjunction with the highly insulated building envelope due to the Structural insulated Panels (SIP) is not losing a lot of heat at night. On a sunny day leading up to a night around freezing the house looses 4-5 degrees until the next morning. His comment was “your heating system won’t have to work very hard”.

This is critical for our project since a highly efficient and well insulated building simply won’t require much heat. We have proven during our open house in September 2009 at our Prefab Green Open House that you can heat the building solely by inviting 30-40 people (in this case some of you reading this) and the heat radiation from their bodies will heat a space. Arrivals during the open house instinctively took off their coats on what was a rainy, cold day.

So here is how we are going to heat our prefab net zero green home, the casa ti:

Heat Collection For The Prefab Off Grid House
We are starting off with 30 evacuated tube collectors by Apricus.

Heat Storage
We are using 2 80 gallon conventional water heaters from our local building supply that we daisy-chain into a 160 gallon heat store. We will choose tanks/heaters with high insulation and will wrap them in additional insulation. The burners won’t be used at all (see backup below) so we can wrap them as we wish.

Heat Delivery
We are using radiant heat. The foundation of our prefab house kit casa ti has 6 loops of PEX tubing, each less than 250 feet of length which is important to deliver heat evenly. 3 loops each are assigned to zones (North and South). The concrete slab rests on 2” of rigid foam insulation where the slab doesn’t support load bearing walls (perimeter and central East/West wall) and the foundation has 2 feet vertical and 2 feet outward insulation.


Critical Backup
An on demand water heater powered by LP gas is spliced into the heat supply to the loops.

Backup While We Are At The Prefab House

A recycled wood stove (the stove Copeland's own family used in the 1980s) supplies heat to the dwelling while we are present. The required heat recovery air exchanger will help distributing this isolated heat source to the entire house as it extracts air (and heat with it) from designated areas of the house and delivers fresh air alongside with the heat extracted from the discarded air to the bed rooms.

And that's that, from Handsome Husband.
In the meantime... stay warm...
'Cause baby, it's cold outside...
and honeychiles...
Happy Holidays!

P.s. If you like pictures (you may have noticed I do), here's more pictures of The Greenbrier, the cottages there, and the drive. : )

A hike, and sledding:

More wanderings...

One last morning sledding, then we headed home:

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Snowpocalypse! Meeting At The Net Zero Prefab Green House Cancelled Due To Snow.

Instead of meeting at the prefab modern house kit with our Fabulous Contractor as planned, we are snowed in at the mid-century modern while Snowpocalypse swirls about us.

So far, halfway through Snowpocalypse Day One, (which began at FOUR A.M. with the children simultaneously asking, "Momma, can we go outside yet? Momma, can we go outside yet?") we have performed Chicken Rescues, gone through six wet pairs of socks per child, four snowsuit changes, and one experimental snow chain drive. Handsome Husband has just saved the day by handing me a hot mug of Gluehwein. It is now 1 p.m. And heck yes, I'm gonna drink it.

So, no new pictures or videos of the prefab green home this weekend.
But it IS storms like this that make us reconsider, "Maybe having a wood stove at the prefab isn't such a bad idea after all..."

Which brings us to the next post from Handsome Husband:
The Net Zero Prefab Green Home Systems Report: Heat.

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Prefab Green Home Systems Post #1 For A Net Zero Off Grid Modern House Kit!

In Virginia it is 22 degrees. Handsome Husband is off cavorting in Florida (Ok, fine, it's work, but *I'm* stuck with the chilluns, dawgs, chickens, fish, and feral cat!), so I will not be visiting the net zero off grid prefab green home this weekend as the logistics to do so alone are overwhelming.

So here come the net zero off grid prefab systems posts, guest written by Handsome Husband: Part One: Rain Water Systems.
**NOTE*: *OUR* systems choices are so minimal and bare bones, you will almost certainly want to consider the more robust packages our partners offer. But our focus as a family is to do as much as possible with as little as possible.**

"I will post our system choices for the casa ti prefab over the next few days. Every post will focus on a subject, beginning with how we plan on supplying the casa ti with water.

We will use rain water collection as the water source. In our area in central Virginia we receive sufficient annual precipitation to easily provide water for a 4 person house hold without having to dig a well. Rainwater collection begins with the choice of roofing materials. Asphalt shingles are not the material of choice as new shingles could leach petroleum products and contaminate the rain water - we chose a metal roof on the southern side of the house for this reason. The northern half of the roof is wrapped in a rubber membrane as a basis for the green roof (vegetation that is as everything seems to carry the term "green" these days). Rainwater from the vegetated roof area should not be used for potable uses but can be used for irrigation and other non potable needs.

We will use a WISY WFF 100 as the primary rainwater filter. This filter receives the rainwater from the downspouts, and separates debris from the water routed to the cistern. We will need to design the downspouts so that they all merge into this single filter.

Next comes the cistern. The first choice is between an above-ground cistern and one that is buried. We are considering going in between in that we would place the cistern in the root cellar. Root cellars are semi-buried structures that enjoy some of the same benefits as geothermal heating: In the winter the stay above freezing and in the summer they don't heat up as much as the ambient temperature. The same will be true for our water!

We plan on using a 1500 gallon polytank intended for freshwater storage (

Now that we have collected, filtered and stored the water we need to pump it into the house. We will extract the best quality of water from the tank which is just below the surface using a floating inlet filter. This type of filter is connected to a floating ball and collects water 4 " below the water surface and comes with 8' of hose to connect to the pump

Next we will install whole house sediment filter. Given the design of the inlet filter I don't expect this filter to collect much of anything but hey, these filters are relatively cheap and collect objects down to 1 micron. (

There is some debate about the need for UV light as an additional purification method. We will have the water quality tested once the system is installed and will see, whether this will be necessary in our application. Until then we will bring bottled water and just cook/shower with water collected from the sky. As with any water system, it is important to have the water tested for water quality. Additional filtration may be necessary once the system is installed and tested. Any water system including wells should be tested at least annually to ensure the water quality remains at the highest level for human consumption.

That's it for this first systems post for the net zero SIPs passive solar prefab, casa ti! Our next post will describe our approach for heating the water (DHW)."

There you have it, straight from the Handsome Husband's mouth.
Now if only he'd only hurry home so I can take a break!
We will be visiting the prefab next weekend as we have a meeting with our Fabulous Contractor regarding our next steps for the net zero prefab green home.

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Modern Reused Bed For A Modern Green Prefab Home

We had hot soup at my parents, on an icy, sleeting, miserable downpour of a winter day.
As you could see in the previous post, even the chickens wanted to come inside!

And even better than the delicious soup, we left the children behind!
What to do with the freedom? 

Honeychile we hot-footed it to our favorite Richmond thrift stores, to browse lazily without having to scold and watch and hurry the little ones!

At Restore (RVA's Habitat For Humanity recycled and reused material goods store on Roane Street) we found a pristine Danish modern bed made of teak with drawers underneath to reuse, recycle into our modern prefab green home! We were so pleased with its simple, clean modern lines, the simplicity, the functionality, the practical uses for our bedroom in the prefab green home and... that it cost...

It did.

We also found a sink!

At another local thrift store we found some large, hardy wine and beer glasses with a thumb print design for 75 cents apiece.

Again, this is in keeping with my careful, treasure hunting philosophy that it is more fun, more stylish, and more sensible to reuse and recycle than buy out of the box.  Seriously, think of the modern prefabs / homes you visit: What are they furnished with? Ikea. Not completely dissing Ikea, but... my home looks like my home because it has no pattern, and why the heck not reuse and hunt through thrift store's treasures so they don't end up in landfills? Serious fun, folks, but it also takes patience and planning.

The patience and planning and scouring for good modern furniture finds is so much fun, and so worth it... we don't look like everybody else, and I love that by shopping at Restore in RVA, I am not only recycling and reusing materials but helping a great cause, affordable housing.

Enjoy! Here's the bed!

And here's more on Restore in RVA:
"Why Should I Shop at ReStore?
Shopping at ReStore is an adventure! Every day we have new inventory to choose from, including furniture, flooring, architectural items, cabinetry, fixtures, wallpaper, appliances and more—at prices up to 90% below retail!  Some items are new, some gently used, and others come from deconstruction.  Not only can you find some beautiful items and great bargains, but you are helping the environment and low-income families at the same time.

It is estimated that Virginia landfills will reach maximum capacity in the next 5-10 years. Approximately 20% of these materials are construction and demolition debris.  In fact, a single Virginia landfill can receive over 50,000 tons of such materials in one year."

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Prefab casa ti: The Interior Load Bearing Wall

If it were just a few degrees colder, we'd be packing up excitedly to head to the prefab green house to then relax on the land, watching and playing in the snow fall.

Instead, it is a slow, frosty rain, so we are staying here, keeping warm, baking cookies and grateful my parents have invited us over for hot soup!

We are using this wet weekend to rest, catch up with work (I had a week of marathon conference calls), to slowly decorate the tree, and get a little more organized than our suitcase life normally allows.

As with all of you, I have been having a great conversation with one person in particular, Bart S., this week.

(The systems post is almost done, by the way, so you can see what we are doing with our own prefab green case you want to do the same thing with your own prefab house. I will also have some new septic / waste water treatment information for you soon.)

Bart had asked about when / how the interior wall of the prefab house kit was built.  There are not as many pictures of that, as Our Fabulous Contractor Ron was the only one taking pictures that week.

So, to more specifically answer Bart's question:
In constructing the prefab green home, the contractor first erected the exterior SIPs house kit walls, then built the interior wall.

You recall the end panels of the SIPs are built on an angle, and that's what gave Ron the height of the load bearing wall. Then the roof panels sit on top of the exterior SIPs, as well as on that middle wall built by the contractor.

(Sorry for the repetition of these old prefab house kit construction photos but they might help explain visually.)

Look closely at these photos and you can see how the SIP roof panels rest on the exterior wall / interior wall:

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