The Concord Consortium

A student design

In a pilot study conducted in December 2012, high school students in an engineering class used our Energy3D CAD tool to do an urban solar design project -- they must consider the sun path in four seasons and the existing buildings in the neighborhood as the design constraints to optimize solar penetration to the new buildings and minimize obstruction of sunlight to the existing buildings.

Energy3D can log any student actions and intermediate steps, which provide extremely detailed information about student design processes. With such a high-resolution lens, we could characterize student patterns and analyze how they solve the design challenge closely. For example, the CAD log allows us to reconstruct the entire design process of each student and show it in an unprecedentedly fine-grained timeline graph. A timeline graph may show how students went through different iterative steps while shaping their designs. For instance, did they consider the interactions among the buildings they designed? Did they go back to revise a previously erected building that may be affected by a newly added one? The timeline data we have collected show that the students' designs demonstrated more iterative features as they moved on to explore and design alternatives following the initial attempts (perhaps encouraged by the gained familiarity with and confidence in the CAD tool).

A design timeline (click to enlarge)

Our analyses also suggest that there appears to be a significant gender difference in both design products and processes. The main differences are: 1) The boys tended to push the limit of the software and produced unconventional designs that looked "cool" but did not necessarily meet the design specifications; and 2) The girls spent more time carefully revising their designs than building new structures. While these findings may not be surprising to some seasoned educators, the significance is that this may be the first time this kind of gender difference was revealed or confirmed by empirical data from CAD logs. Using CAD logs may provide a fairer basis of assessing student performance based on the entire learning process rather than just looking at their final products or self reports.

Summary of the results

The implication of this study is that if we can identify patterns in student design learning and understand their cognitive meanings, we could devise a software system that can provide real-time feedback to help students learn in the future. For example, could the software prompt students to consider the design criteria more when it detects that students are ignoring them? Could the software stimulate students to think out of the box more when it detects that students are underexploring the design space?

For more information about this research project, visit: http://energy.concord.org/research.html.

A Trombe wall is a sun-facing wall separated from the outdoors by glass and an air space. It consists a solar absorber (such as a dark surface) and two vents for air in the house to circulate through the space and carry the solar heat to warm the house up. In a way, a Trombe wall is like a machine that uses air as a convey belt of thermal energy harvested from the sun. Trombe walls are very simple and easy to make and are sometimes used in passive solar green buildings.


Hiding sophisticated power of computational fluid dynamics behind a simple graphical user interface, our Energy2D software can easily simulate how a Trombe wall works. The two images in this blog post show screenshots of a Trombe wall simulation and its closeup version. You can play the simulation on this page and download the models there. If you open the models using Energy2D, you should be able to see how easy it is to tweak the models and create realistic heat flow simulations.

Solar chimneys operate based on similar principles. Energy2D should be able to simulate solar chimneys as well. Perhaps this would be a good challenge to you. (I will post a solar chimney simulation later if I figure out how to do it.)

Engineering design is a lot of fun. The variety of engineering systems students can realistically design and build in classrooms is, however, limited by the constraints of time, resources, and student preparedness.

Currently, construction toys and computer programming are perhaps the most frequently adopted student projects for learning engineering design. These applications cover a number of domains such as robotics and software engineering. 

In our Engineering Energy Efficiency project, we have been working on adding a new option of engineering project that students and teachers can choose to learn and teach engineering.

This Green Building Kit we are developing needs only paper, cardstock, foam board, among other typical office supplies and widely available sensors. Yet, it will allow students to design, build, and test energy-efficient model houses with considerable green features.


An example I am working on is a hot air collector (HAC, also known as the Trombe wall). This is actually very easy to construct (hence a popular DIY project for those who are "green"-minded and handy). It is not difficult for students to add an HAC unit to the sun-facing wall of a model house.

In order for students to have fun with this design challenge, we need to show them that there are a variety of things that they can learn, emulate, test, and invent.

HAC units are usually installed to the part of the sun-facing wall that is not occupied by windows. Windows are necessary to a house because they let light in, but they generally lose more heat than an insulated wall. An insulated wall keeps the heat inside the house, but it does not do anything to collect the heat from the sun and give it to the house. The idea of hot air collector is to use the surface area of the wall that is exposed to the sun to collect some solar energy for warming up the house.

If you think about this engineering design task, it is really a problem about the optimal use of the sun-facing wall surface. So where should we put windows and HAC units and what is the best way of using them? The above images show a variety of designs. Click each image to enlarge it and see the details of each design.

The fourth design combines the benefits of windows and HAC units. It is basically a large HAC unit with the middle part replaced by a window. On the one hand, sunlight still can shine into the house through the two layers of glazing (we automatically have a double-pane window). On the other hand, as the HAC unit is tall, the convective heat exchange between the HAC unit and the room will be more significant. I haven't seen an HAC design like this, so this is my little "invention." Well, I am pretty sure some guy has thought of this before and there is probably a pending patent for this, but never mind about this, I am just demonstrating how an engineering design process in the classroom could be made more inventive.

Our next step is to make it possible for students to add these green architectural elements (HAC is just one of them) in one of our flagship products: Energy3D. Energy3D already has a powerful heliodon for solar design.