Mid-Flight Corrections

Our test building has been complete for a couple of weeks now. I've been busy digesting some of the lessons learned. No doubt, some experienced adobe contractors (few if any in our neck of the woods) might say, "of course, we knew that!" I can fully appreciate that. And there's certainly no substitute for carrying the "thinkin'" to the "doin'" on your own, and that was more than true in this instance.

We learned a great many lessons on material prep, staging, handling...a great deal on block "tweeking," etc...and even more on the plaster phase. I think it might be instructive for those of you following the blog for me to give a debrief in outline form on lessons learned. More to come on that.

I will have more pictures posted soon but will start with the set below. You can see our finished structure as it stands now. The deep overhangs gave us a nice framework for protecting our still-drying plaster from rain with plastic sheets. The roof design mimicks the multi family project specifications and has a big impact on our energy modelling. We get the added bonus of great protection for the walls from rain. The front (eastern exposure) has a 4 foot over hang, 3 feet on the back (western exposure) and 2 feet on either side (northern and southern exposures.) These orientations do not match our project site which will be 4 feet to the west, 3 feet to the east, and 2 feet to north and south. We're spec'd for exposed rafters etc. as you can see by clicking the thumbnail below which is a google sketch up model of our multi family project.

click thumbnail above for full size image

One huge lesson learned (and I dare say I was told as much but just didn't quite snap to) was how much more efficient our build would be by not integrating CEB into our door/window sections. That one front section seen in the photo above that included the door, window and polycarbonate panel infills had a multiplier effect on our time on the build that I feel will dramatically impact the economics of our future projects. Part of the goal was to learn, which we did, but also to start demonstrating the cost efficiencies and energy efficiencies (costs going forward) of using earth construction techniques like CEB. We have already started modifications to our plans to fit to the design and to reflect our build experience.

You can see Daniel hard at work here working out the details on the door and window section. Again, huge drag and inefficiency on this element. But then, that was the purpose right? To learn, calculate and reconfigure!

While my intention with the photo above was not to be artsy in any way, my unique angle does serve the purpose of illustrating several interesting elements. First was the tile Aurelio selected which I thought looked rather "cheesy" in the box....but ended up looking great on the floor. Just goes to show why I don't pick design elements and he should be nominated for some future Earth Architecture Design show!

One item of note is how the guys figured out that by rotating the blocks on their side, we ended up with a more stable wall section between the door and window that was just right for a 2 switch panel for lights. The opening for the box was created by cutting a block short to match the depth of the box, something they repeated in the walls to practice for electrical conduit and junction boxes for outlets. If you look closely at the photo above you can see a plaster variance about a foot off of the floor on the left hand wall surface. By cutting blocks 1 inch short on that course, and 3 inches short where junction boxes would be installed, we were easiy able to provide the necessary cut outs that could be plastered and hidden.

All in all a very worthwhile experience. Modifications ahead on this structure for demonstration purposes include removing sections of plaster inside and out and replacing with alternative treatments, completion on the passive ventilation design (worthy of a full blog post when completed) and the installation of data loggers by John Morony. We're all excited about the future data stream which I will figure out how to graph and keep updated.

3 pizzas, 1 shovel, 12 beers...

....not a George Thorogood song, but it is the final push to inspection day! What was expected to be an easy and quick roof framing turned into quite the work of art featuring a 4 foot overhang to the front, a 3 foot overhang to the back and 2 foot overhangs to either side. Excellent for pasive cooling what already figures to be a very "cool" building to begin with due simply to thermal mass and walls that breathe. It wasn't as easy as it looked on paper but the crew did a great job. 

You might notice the wall section half dark, half light. The dark section is where they sprayed the wall with water. Sprayed with water?! That's right...the lime plaster won't adhere to the building without a moist surface.

Speaking of plaster...here's a picture of David preparing a batch of traditional lime plaster. Beautiful stuff, really, comprised of sand, lime, marble dust, hay and, of all things, nopales cactus juice.

Someone needs to supervise the material prep...might as well be the boss!

Nopales cactus-infused water renders a natural and very effective latex. Sometimes I wonder if we invented solutions to problems we never had and materials that already existed!

And, finally, the plaster goes up. Beautiful in color, remarkable in texture and extremely effective in not only protecting the walls from the elements, but in maintaining the ability of the walls to "breathe." Referred to as latent heat flux, or the ability of the walls moderate temperature by absorbing and giving up moisture, this "breathing" is credited with a healthier interior air quality and with helping to keep the building cool.

And as the sun sets, the guys are still at it. In fact, they are STILL at it as i write. It's a great crew on the project with real commitment to a quality outcome. Sourcing materials, making and stacking blocks, plastering...all phases very labor intensive. I asked Robbie, the crew boss, if he had it to do all over again, would he prefer to go back to stick and stucco construction. His answer? NO! "This is a superior way to build...and results in a much better building...it's worth it." Amen!

Rounding the home stretch

The beginning of the new year finds the crew completing the ceb wall sections to the proscribed heights at either end, 8 feet and 11 feet, and prepping to lay the wood bond beam. We chose wood over concrete for cost reasons, weight reasons and in the interest of simplicity. The blocks took the screws beautifully and provided very impressive anchoring. Which is not really surprising when you see the cross section of a block in the picture below. The block was cut with a miter saw and a wood blade. Not a happy moment for the blade, but an effective means of cutting bevels in the blocks for our sloping side walls.

With the bond beam in place, the roof rafters started taking shape. We have very deep overhangs specified for the roof, 3 feet over the short end of the structure, 4 feet over the front, and 2 feet to either side. This will help protect the building from the elements and provide a lot of shade around the walls. We're a hot humid climate zone so the shading is an important part of the passive cooling program.

Final roof details were worked out today and yours truly, the solar chimney man, just had to find a way to put all that great summer heat to use COOLING the structure. More details to come as that unfolds. 

The guys working on this project are developing some great skills and are showing talent in executing a loft style ceb structure. With the roof structure complete tomorrow, plastering can begin in earnest. A subject worthy of a post in and of itself. We'll be using a traditional lime and clay plaster ammended with nopales cactus "juice" which provides a natural latex to the mix. I haven't personally seen it, only had reports of how beautiful it looks. Looking forward to that part.

Who Needs a Gym Membership?!

Each of one of the compressed earth blocks used in this project weighs about 26 pounds. At approximately 48 blocks per linear foot on an 8 foot high wall section that calculates out to 1,248 pounds per linear foot. The rear wall of the building will be 8 feet high, the front 11 feet high in sections with the side walls sloping to meet the front. I don't know what a similarly sized building of conventional stick frame construction would weigh, but I doubt anything close to the 60,000 pounds or so of weight this build will!

Something that weighs so much deserves a name I think....perhaps "la casita ocho" would be appropriate given it's location behind old fire station 8. Or maybe even "la gordita!"

It's no wonder then that our intrepid crew is tired and sore at the end of a long day of block wall construction. I've joked with them that they need to star in that gym commercial where the guy simply says, "I pick things up, I put them down!" 

You can see the crew below hard at work putting the walls up in earnest......

...with great progress toward our first goal of an eight foot wall section.

Through trial and error the guys put together an optimal system of material handling, block making, equipment positioning and wall construction. Lots of detailing decisions were made as the door and window sections were added..then removed...modified...and replaced. You can see one of the retrofits between the door and window bucks. We had originally placed a pilaster between the door and window of 2-3 blocks wide. That detracted from the loft style look we were after so the command came forth to remove the pilaster, bring the window buck closer to the door and to leave just enough space for a dual light switch. Easier said than done! Removing the blocks that had been set in place with slurry proved to be one heck of a task a mere hours after they had been set. It was a true testament to the solidity of this construction methodology. They succeeded in the task and found that a block laid on edge between the door and window bucks provided just the right amount of space for the light switch and preserved the integrity of the building shell in terms of it being all compressed earth block.

But what would any job be without equipment failure?! The bobcat blew a hydraulic line late in the day, slowing block production. The bobcat has proven to be an indispensible tool in moving and working dirt, then bringing it to the block press. Men or machines...an age old calculation! In this case, we love the bobcat!

And with the setting sun, we find Robbie, boss of the job, still hard at work towards his goal on the rear wall section. This section has the western exposure and will carry the greatest heat load. My intention is to set the fresh air intake grills in the corners on the floor on the western wall. I'm no engineer, but with solar chimneys at the roof peak on the eastern exposure I'm betting on very effective drafting of any heat that manages to find its way through 12 inches of compacted earth on this wall. Other passive cooling concepts will come later with landscaping. The pecan tree behind will also provide significant shading. In fact, so much so that mounting solar panels on the roof would likely not be a possible energy strategy for powering DC fixtures, something we had considered for research.

Solar Chimneys and Earth Architecture

It was my curiosity about passive cooling that brought me to earth architecture in the first place. A particular interest of mine in researching passive cooling is the concept of the solar chimney. It's a feature we will include in our test structure. One great solar chimney example brought to my attention is at the Hawaii Gateway Energy Center. In fact, it's not AT the center, but integrated INTO the building of the center itself. You can read more about the concept deployed here: http://www.energyfuturehawaii.org/learn-more/7-renewable-energy-a-energy-efficiency/66-thermal-chimneys-and-passive-air-conditioning-.html.

Solar chimneys and Persian wind catchers (bagdirs) are certainly nothing new. In fact, I saw a great example of a wind catcher at the Cal-Earth institute a couple of weeks ago on a visit to their site. I didn't expect to see that as part of their demonstration project and was thrilled to see a working example. Unfortunately I was there in winter and didn't get to experience how it functions in the desert heat. Our guide at the center, however, indicated that it worked extremely well to circulate a cooling breeze in the summer.

Our own Firehouse 8 has a superb set up for several solar chimneys and we'll certainly be integrating those into the passive cooling strategies planned for the building. Large ceiling mounting gas heaters used to warm the truck bays have been removed and we will be improving the vent pipes that lead to the roof to create natural convection of warm air off of the ceiling and out of the building.

Drawing hot air out, implies drawing COOL air in. That is the major design challenge we face. The Hawaii center illustration is a clever use of cold water and is a very interesting design. Simple earth tubes have been considered (nice write up here: https://www.thenaturalhome.com/earthtube.htm) but are generally discouraged for hot humid climates.

Watch for future updates on our solutions in this arena. The appeal of being able to draft a lot of fresh air indoors and improve air quality while cooling is very appealing!