So I have been lurking and didn't find much in the way of this, perhaps it is a good discussion given the extreme climate conditions I present.

I am planning on building a home in Guadalajara, Mexico. For those of you who do not know, from the poorest to the richest in Mexico build their houses with hollow concrete block, poured concrete columns, floors and roofs. Yet even the richest here who build mansions do not practice green building with insulation and efficient windows. Someone will spend $10M on a 25k sq ft mansion but put cheap single pane windows in. Given the climate, there must be better alternatives...

Climate: Very extreme, averages highs 85F+/- year round, two months of the year average around 100 with days 110 and some humidity. 4 months get around 8 inches of rain per month. Most nights from around 3am-5am drop down to the 50's in summer and 30's in winter.

I am much bigger on spending upfront and minimizing long term monthly costs (the price of power is astronomical here)and I also like to be comfortable, keeping the house at 78 at all times and I am looking at around a 9,000sq ft house... also planning 10kw solar array.

Given the local workforce are experts in concrete block construction, what would be a good strategy maximizing local labor and minimizing imports (insulation products, etc...) I am already planning on importing all windows, probably Pella.

Since it is a fresh build would filling the hollow cinder block with foam insulation be enough? I have been talking with local architect about how much wiring will go in (high tech house) so she suggested it might be easier to frame the inside of the house with steel stud and dry wall over it... Would filling that steel stud on the interior with insulation also be a good idea or would the foam in the cinder block be enough? Keep in mind the main aspect here is keeping heat out.

I have consulted with some contractors in San Diego but they seem to have a tendency to build to bare code requirements and underestimate. I am more concerned with long term satisfaction and comfort than to save on the building. Maybe someone can help with a rule of thumb and suggest a contractor that might be willing to travel.

Thanks!

With temperatures above and below comfortable, thermal mass is a plus. But since you want constant interior temperatures, you need to put it on the exterior. You might consider SCIPs - a concrete, metal mesh, foam sandwich. Whatever you do, put lots of effort into air sealing. Also, large overhangs and a white roof.

2 inches closed cell foam on exterior

What jonr said. (Except that SCIPs are probably going to be a more expensive way to build in Mexico.)

Insulating the exterior with foam (rigid or sprayed) will be a HUGE benefit compared to interior insulation, or worse, simply insulating the cores of the cinder block which leaves significant thermal bridging in place. Filling the cores of the blocks with sand/concrete/stone to increase the thermal mass would be a better use of the volume than insulation, once you have at least R5 of rigid foam on the exterior. That way the interior space will stay within a few degrees of the thermal mass, averaging out the daily swings in temperature, reducing your peak heating & cooling loads.

A cavity wall approach with either a stucco/stone/thinner-block veneer with at 1.5-2" of foil-faced iso (polyisocyanurate rigid foam) or XPS (extruded expanded polystyrene) would be the cheaper way to go in Mexico: eg :http://www.maconline.org/tech/design/cavitywalls/cavitywalls.html (Don't cheap out and use white EPS bead-board- the ants will destroy it pretty quickly in that climate.) The cavity has to have both top venting and weep holes at the bottom to purge moisture that seeps through the exterior masonry. During the rainy season moisture drives will be intense- sealing the exterior masonry with a silane-based masonry sealer can cut that moisture drive significantly. Taping/caulking the seams in the foam will limit the amount of moisture finding it's way into the interior cinder block, and can be made into a reasonable air-barrier. Using foil-faced iso measurably rejects some of the heat radiating in from the exterior masonry, and would be the better choice if you can get it easily. The seams can be taped with purpose-made aluminum tapes (be sure to use only the right stuff- the adhesive has to be formulated properly to hold up over time.) Spray closed cell polyurethane foam would also work at ~1.5-2" thickness, but that can be dramatically more expensive.

Optimizing the windows & overhangs for seasonal solar solar rejection would also be important. Overhangs can help on the south side, but minimizing size of east & west glazed area (and using only heat-rejecting low solar gain windows) will be important. The greater the overall window area, the higher the solar gain, and the lower the overall R value.

Classic ceramic roofing can work well, but metal roofing with a California Title 24-compliant "cool roof" finish works better. White color isn't as important as the comparative aged solar reflective index and infra-red emissivity, but most cool-roof materials are lighter than terra-cotta red. Terra-cotta has a high emissivity (==good), but isn't optimal for solar reflection (in both the infra-red and visible spectrum) as some others- not bad, but there are better. (Light colored concrete tiles work pretty well.) See: http://www.coolroofs.org/ http://www.coolroofs.org/documents/CaliforniaEnergyCommission-Title24Update.pdf Some white finishes (including some bright aluminum paints) have too low an emissivity to work, despite being highly reflective of entire solar spectrum.

I've been watching the use of SCIPs in central america and it looks like a wash cost wise - less expensive if you want insulation. I was looking at a mostly complete one a few days ago and the walls were sturdy, straight and smooth. I'm not so convinced about using it for ceilings or roofs.

Planting trees helps (for shade). Also, direct solar gain isn't the only thing to consider - indirect is substantial. Ie, the suns heats up the ground and any window with a direct view of the ground gains heat. So deep overhangs (or a covered porch area) helps more than you might think by looking at sun angles.

You might consider an automated ventilation system that maintains the ideal temperature - I find that opening/closing the windows multiple times/day gets old.

What about the classic "adobe effect"? I'm not sure Guadalajara is well described by "tropical". At an altitude of over 5,000 feet, it's nearly as high as Denver. Because of that, it has those colder nights and that may be why the building construction stays with the simple block. Isn't it the classic situation where the thermal mass provides inertia vs the daily temperature fluctuations?

There must be local architects who have some sense of what is most energy efficient using local skills and materials.

Hey guys, thanks for your input I really appreciate it. I think I misspoke in putting semi-tropical. I meant semi humid. It is definitely far from tropical at that elevation and if anything it is pretty arid aside from the overwhelming rainy season.

So concentrating on exterior insulation seems to be the key, then just plaster over that or use some sort of sheathing?. Also filling the block with earth would be better than blown in insulation? These are all important notes for me!

Regarding the window positioning, the lot is a North-South lot. The sun here beats down hard and having east-west facing houses i have noticed is a huge mistake after renting an apartment for 3 years with that direction and floor to ceiling singles pane windows. (???). Properties here are small and surprisingly expensive. We threw around the idea of a central courtyard Hacienda style house with all windows covered by a 15-16 ft roofed terrace. I settled for a design with more common walls and more sq feet that looked out instead of in, it permitted a more compact footprint, better layout, since the lot is only 14,000 sq ft. Still the large ground floor windows have a 16ft roofed terrace and the second floor windows are somewhat small and few. All windows except for some very small bathroom ones will have north south orientation. Efficient lighting will be much cheaper than running the AC for longer periods of time.

Believe it or not, the efficient way of building (as suggested by some local talent) was to build double thick brick walls haha. I know enough to know that this would nearly double the cost of the house and bring the walls to like an R4 or something. There does not seem to be any regard for R rating down here and instead just window positioning and shading, yet still cutting costs on any insulation or multi pane windows.I cannot believe some "modern" condos here sell for over $1 million USD, completely surrounded by East-West floor to ceiling single pane, non glazed, windows that heat the units up to 100F in the morning and afternoon unless you blast the AC, even with it 70 outside. Yet these buildings will be constructed out of twice as much concrete than in the US and have same finishes and appliances, which makes me think its less on cost skimping and more on lack of knowledge on efficient building