Week 2

We have received permission to start building and have marked off our designated site! We received a few bags of cement, lime and sand today as well as other necessary building supplies.  As soon as the rest of the materials arrive early next week, we will begin making blocks and constructing our model home. In the meantime, we have been researching possible directions we would like to explore once our control model is built. To maximize productivity, we split into two groups to look at different components.

One group has done comprehensive research on ventilation, looking into several ways they can modify the existing techniques to allow for more airflow. This is a vital and often lacking component to homes in Senegal, but poses a lot of potential issues. The goal is to create air circulation while preventing heat, bugs, and sand from entering the homes with the fresh air. Our first idea is to create all of the walls out of CMU, with a bottom row made of brise soleil blocks. We want to incorporate a type of screen mechanism in the brise soleil openings to prevent the entry of mosquitoes. The top of the building will have a row completely open brise soleil. There will be a barrier below that row which acts as a ventilation barrier and bug screen between the living space and the top of the house.  The top brise soleil blocks will be where most of the sunlight enters the house for visibility.

The big question of the week was Why do homes in Senegal not have screens when disease carrying mosquitoes are such a big issue? We came up with a few reasons, such as screens make the homes appear unwelcoming, they can easily damage in weather, or they are simply not cheap for people in Senegal to buy. We tried to experiment with different ways we could hide a mesh screen into a brise soleil block so it is not visible. Next week we want to explore different textiles people could use instead of metal to make it cheaper and easier to obtain for senegalese people. The 3D printing sustainable development group wants to work with us in the future and we are hoping to find a way we could 3D print screens with plastic made from recycled plastic bags.

We also experimented with different ventilation systems such as thermal chimneys and wind scoops. Thermal chimneys have a metal material on the top which attracts heat.  Below there is a corridor that allows air to rise and then funnel out of the building, circulating cooler air up through the house. The same concept can be applied to the south facing fall of a building. Heat is attracted to the metal wall and then a corridor helps funnel hot air up and out of the building. The corrugated metal roof is beneficial to these types of systems, instead of heating up the building to extreme temperatures like they are currently doing in Senegal.  Wind scoops can be used in multiple sides of the dwelling to help direct incoming winds through the space.

The other group continued researching earthbag construction and brainstormed how we could expand upon existing techniques being used in similar areas. A square or rectangular home constructed out of sandbags would look very similar to the existing concrete homes in Senegal once they had been covered in cement. The problem is that a rectangular structure typically needs wood frames distributed among the sandbags. Since wood is not widely available in Senegal, dome shaped structures would probably be a more viable solution. While these may provide different aesthetics, they also open up other opportunities for building.  

Since the dome shape tapers up to the top, one idea we had was to build a screen or some kind of low emissivity barrier into the sand bag layers towards the top and then leave the very top open. This way air would enter through the door and windows then the hot air would rise to the top and exit the building through the top. The screen would prevent bugs from coming in and then some kind of slightly elevated, removable or permanent cap could go on top to prevent rain and direct sunlight from entering. We could also easily incorporate a rain collecting device by adding a slanted ledge near the bottom of the dome that would collect the rain and siphon it into one area to be collected.

Another idea we looked into was incorporating sandbag homes into the traditional Senegalese compound and courtyard. One way this could be done is by creating one large, torus shaped building that housed a courtyard in the middle. Some things to consider are the fact that this type of building would probably require a separate roof and the shape of the building would not really allow for additional buildings to be added on to the compound as they typically are in Senegal. We also considered building lots of small domes and bridging them together as they get added on. This would allow for small corridors that could be treated as communal space and would also allow for an outdoor courtyard to develop naturally as it does with the current building techniques.

Ideally we would like to be able to construct two additional smaller scale models to test some of these ideas once our initial building is complete. Then we can compare them to see what is the most efficient building.