Underground houses for hot days

The traditional buildings where we are in the Andes1 are built to stay cool on hot days. They have thick rammed earth walls, tall ceilings, large doors and windows to provide draft, wide corridors for shade, and are often in the shade of big trees.

We have built that way too, although it still gets hot on hot afternoons, especially in the dry season.

I am thinking of building an underground building with a living roof near the main houses. It will function as a living room on hot afternoons, and perhaps even a bedroom on warmer nights.

Building it into the ground will keep the temperatures down, as will the living roof.

As for details, I am thinking of a round room, 4-5 meters interior diameter, with stone walls, and with the wall facing out also in stone with a large door. It will likely have ventilation shafts to create a nice draft.

The walls will need a water barrier, and the roof may need extra insulation in addition to the soil and plants.

The main space is down a few steps from the entrance level. This allows the building to be built further down into the ground, and it will create a space to collect the cool heavier air that sinks.

I will have to explore what plants are suitable for the living roof. They need to have relatively shallow roots and be drought-resistant. A variety of succulents may work well.

We will also plant trees for shade, and create a multi-layered food forest around the house to further reduce the temperature.

It will not have a kitchen or bathroom since those will be in the main buildings. This is more of a retreat and/or cooling space.

Daytime temperatures are typically between 20 and 30 degrees Celsius, with rare days above 30 degrees. Night temperatures are typically in the mid teens to low twenties. I slept outside during the hottest time of the year, and it was comfortable. I suspect the temperatures in this room may be between the high teens and low twenties.

Why don’t they traditionally build into the ground in this area? I assume it’s partly because they don’t need deep foundations (no frost) so they don’t have basements2. And it has also not been necessary. These days – with climate change, increasing temperatures, and more extreme weather – it makes sense to include at least one underground room. For all I know, this may be the first in the area built in this way. (Some friends of ours have outdoor toilets built similarly, but it’s not a living space.)

The drawings above are two quick diagrams I made of the plan and elevation.

(1) Barichara at 1000 meters above sea level and 6 degrees north of the equator.

(2) When the ground freezes, the foundation needs to go deeper than the frost. In cold climates, that means it makes sense to have basements since they already dig quite far down so you may as well make use of the big hole in the ground. In climates without frost, the foundation doesn’t need to go very deep into the ground, so the hole is more shallow, and it makes less sense to make a basement out of it.

Water in Barichara

Barichara has wet and dry seasons. The dry season is usually December-April, with two or three good rains within that period. Some years, it rains a lot through the year. In other years, the dry seasons last longer.

We are in the dry season and just had a very welcome early morning rain here. I measured it, and it was around 5cm. I imagine many beings are very happy for it – people, animals, birds, insects, and plants.

The roof of our small house is about 100m2. 1mm of rain on one square meter gives 1 liter of water. 1mm of rain on this roof is 100 liters. This rain gave 5,000 liters of water from the roof. That’s quite a lot.

There is no lack of water here, and it is important to manage it well.

FINCA MILAGROS

We collect water from town in one large and one smaller tank. That means we have water for a while even if the water from town doesn’t flow.

We will install a several-step water filtration system (from sand filter through eventually UV light) for clean drinking water. The alternative is water from large plastic bottles, which is terrible due to all the microplastic particles in the water (200,000 in small plastic water bottles from a recent study).

We will soon start collecting rainwater from the roofs here. I am not sure how big the tanks will be, and we may expand. For now, we are thinking of 2×15,000 liters for the larger house that’s being built (220m2 roof surface) and one 15,000-liter tank for our small house. These tanks will be filled up quickly with some good rains, and we will use the water to water plants. (Perhaps also for showering etc., not sure yet.)

Finca Milagros has one large pond and 3-4 smaller ones. We want to channel rainwater better into these ponds, and make them deeper, so they can hold more water. This is important for the birds, animals, and insects relying on that water, it helps the vegetation and life in the areas around the ponds, and it also helps to replenish the groundwater.

The land here has been grazed so only the area around the big pond has a more mature forest. The rest is various degrees of young forest and arid land. Vegetation helps slow down the flow of water and helps the water absorb into the ground, so that’s one of many reasons we are planning to reforest the area with native trees and bushes.

Bare soil is eroded when it rains. That’s why we are planting cactus and succulents there, mostly native. We are also planting hardy native trees there, mostly boca ratón right now. And we are doing some simple landscaping, mostly with rocks, to reduce erosion.

There is a dry river going through Milagros. It’s dry because of deforestation. Forests bring water into the ground (slows the water flow and makes the ground more porous) and reduce evaporation, both of which give water to the river. With reforestation, there is a chance we can bring the water back into the river, especially if we are also able to help reforest the land higher up.

BARICHARA

As far as I know, there are no groundwater regulations here. That’s enormously important. We need to prevent too much use and contamination of groundwater. (Many houses here use septic fields that leach blackwater into the groundwater.) Depleting the groundwater reserves has a huge impact on the ecosystem. Both depleting and contaminating it has serious and devastating consequences for the very long term. Protecting the groundwater is hugely important.

The water that comes from the municipality (aqueduct) is contaminated. That’s another important thing to work on since not everyone can afford good purification systems or to buy drinking water separately. It’s a vital public health issue.

Reforestation is also hugely important. Forests hold humidity and create rain. The other side of Cañon del Chicamocha has more forests and there are always clouds there. I assume they also receive more rain. They (partially) create rain for themselves.

The photo is of the other side of Cañon del Chicamocha at sunset

agua, barichara, santander, agua subterránea, protección del agua