TSA joint project: Diving into the design process

16 December 2020. The first meeting starts at 8 a.m. Project: Hostel, East Africa

In addition to facilitator Pablo, the other Fellows are in the online conference - this time via Zoom - joined by the local architect and his team, and former TS Fellow Achilles Ahimbisibwe (Associate Dean at Uganda Martyrs University) as an on-site consultant. The "pilots" Michelle Hur and Mohammed Hamza are present; Monika Lauster and Bertram von Negelein are listening in; it is also important to record this stage of the first joint project of the TSA7 Fellows.

After the round of introductions, the first questions reveal details. Edge certification* is being heavily considered but will not be analysed in detail for the time being. Uganda's grid electricity comes mainly from hydropower, but the infrastructure is not very reliable. The power can be out for long periods of time, and it is expensive. For this reason, too, it is planned not to install any power sockets in the dormitory rooms. In addition, no one will be tempted to cook secretly in the dormitory. The trainees will receive their food from the school.

In Uganda, it rains on average twice as much as it does here in Europe, so water is not actually in short supply, but this does not mean that it is not an issue, especially since the city's plumbing system is not particularly well developed.

How are the trainees normally dressed? This question is allows the Fellows to calibrate comfort measures according to clothing level. The usual school uniform of skirts for girls or trousers for young men allows the locals to be comfortable in this climate. There are no set routine for dorm occupancy. Classes are variable; trainees return to their dorm rooms intermittently during break periods. They generally stay on site during the semester; hardly anyone goes home for the weekend.

Sandhiya presents various options for shading for consideration. She shows examples made of bamboo. The architect emphasizes that a robust solution should be aimed for, requiring as little maintenance as possible. Eucalyptus wood is popularly used in Uganda. The desire to hang clothes in front of the east windows to dry should not conflict with shading strategies.

Ana proposes ventilation strategies. We learn that fans are rarely used in Uganda. "We don't need them," we are told. Whether this is primarily driven by power costs and maintenance remains an open question. On the other hand, there is sometimes so much wind that one would close the window from time to time. By the way: mosquito nets are never used there with openable windows, only with permanent ventilation openings they are standard. The humidity in Kampala is said to be not as high as in more northern regions of Uganda.
The example of ventilating the rooms naturally and with little technology via solar chimney arouses curiosity. It is true that noise transmission via the air duct from room to room and possible additional costs have to be considered. However, these costs must be weighed against the potential savings from the reduction in windows or in window sizes. Transsolar has examples of schools in its portfolio which demonstrate successful implementations of stack ventilation (with good air flow and no acoustic problems).

Francis takes his turn. He presents options for water collection, use and treatment, which include capturing and collecting rainwater from the roof, using gray water for flushing toilets or for irrigation. Four showers and four WCs are planned for each floor; on top of that there will be laundry areas where trainees can wash their clothes. Black water is typically collected on site in a septic tank and emptied as needed. A septic digester, on the other hand, could be used to produce biogas for further use. Another option would be to use composting toilets, which require urine to be collected separately and require an absorbent material such as sawdust or ash for the solids. Also, a biological treatment plant is theoretically possible; this would require the construction of a vegetated pond. A sketch shows how the fresh, rain-, grey- and blackwater systems interconnect. And again, the question arises, which system requires the least amount of maintenance? In the event of an operational problem, it usually takes quite a long time to resolve the problem, in the architect's experience.
To move forward here and to estimate costs for comparison, Francis now needs to estimate of all sorts of values: How much water should optimally be stored on the roof, to balance structural costs and the daily water demand? How big do the main rainwater cisterns in the ground have to be? How much gas can be extracted from solid waste? What water requirements can be expected? Achilles can obtain and pass on values for this.

Ketan leads the electricity discussion. From the design team, we learn that excess power from a photovoltaic array can only be fed into the public grid in special cases in Uganda. This unfortunately means that there is no option to sell the surplus electricity of a PV system during the day and to get paid for it. If there is only lighting with LEDs in the building, a small area on the roof equipped with photovoltaics would be sufficient. However, the 2600 m² roof has a much larger potential to generate energy. Its amount also depends on the angle of inclination at which the panels should be placed, so that they clean themselves without maintenance, even when it rains. The energy generated would have to be used during the day, not just by pumping water onto the roof. It is conceivable that it could be used in the school about 100 m away, and a battery system would be used to store electricity for the night.

Finally, more questions are asked, and other open points are collected:
How big do the windows need to be to get enough daylight into the rooms, or is daylight needed from both sides of the rooms? For sure, the students sleep in the rooms, but the curriculum is irregular, school hours are intermittent throughout the day; trainees frequently return to their rooms then. It should also be noted that it can rain buckets in this area: A good stormwater management plan would be advantageous. A few material options are also open. A skeleton of reinforced concrete will support the building, the use of Zero Carbon Panels (special sustainably produced panels based on straw by-product) is certain. For the washrooms and showers, a wall design which allows air and light transmission is desired and remains open for discussion.

By next week, before Christmas, Transsolar will put together a "Booklet of Options," a compilation of possibilities. The next meeting is scheduled for January 13, 2021.

*Example: to achieve the EDGE standard, a building must be 20 percent more efficient than a standard building at that location in three categories: energy, water and gray energy of materials.