Building Technology Laboratory

This term the course focuses on technical studies in support of schools in Haiti that are being designed by Architects for Humanity. The course has very recently been jointly listed as the D-Lab: Schools course; depending on enrollment, this will lead to complementary studies of a school in Ghana and expanded discussion of education in Haiti and Ghana. Investigations of schools build on previous work with the Building Technology Program in support of schools in Pakistan, Sierra Leone and Cambodia. Studies in 4.411 this fall will include simulation, construction and test of models, and comparison of simulation with experimental data.

The first lab concerns daylighting, important in schools that initially will have little or no electricity or other means of providing light. A physical, reduced-scale model of one or more classrooms will be constructed, realistically representing the optical properties of materials to be used in the planned school and already in use in existing schools in Haiti (and, throughout this overview, in Ghana if the course expands as noted). The model will be fitted with small photometers to measure daylight levels and tested in Killian Court, orienting the model relative to the sun to mimic the position of the sun in Haiti. The measurements and a design procedure for windows and skylights will be used to modify the model to improve the indoor lighting. The model will then be re-tested and results will be compared with those obtained by constructing a CAD model (SketchUp or AutoCAD) and simulating it in Lightsolve, a ray-tracing program that offers estimates of annual performance, or Lightscape, a radiosity-based simulation program that is good for snapshot assessments of daylighting.

The second lab takes up natural ventilation, needed to remove heat generated by the occupants and, as a function of window shading, by the sun. This lab will include airflow tests in model classrooms, using a fan to mimic winds or, with favorable scheduling, the Wright Brothers wind tunnel on campus. Simulations will be made with a series of increasing capable tools, including steady-state calculations of buoyancy-and wind-driven airflows using CONTAM, available from the National Institute of Standards and Technology (NIST); dynamic simulations of indoor temperature changes due to airflows, using the CoolVent program developed at MIT; and a computational fluid dynamics (CFD) program, PHOENICS, to examine airflow patterns within classrooms.

Building thermal dynamics will be studied in a short lab that will include construction and testing of a reduced-scale passive solar classroom intended for colder climates. Temperatures will be measured will electronic data loggers. Results for a week-long test (possibly repeated to allow an assessment of improvements) will be compared with predictions made in a spreadsheet-based simulation. Further simulations will be made with Matlab, accounting in a more realistic way for the flow of heat in and out of the materials of the model and with the very capable simulation package EnergyPlus, via the DesignBuilder interface. The simulations will be used to study temperature dynamics and thermal comfort in Haitian schools. A final report will summarize the building thermal dynamics lab and all previous work.