Ekotrope Program Designs Energy Efficient Homes
Designing energy efficient homes isn’t rocket science. Or maybe it is. How do you know what the best combination of efficiency and cost is for your particular home? With six types of walls to choose from, five kinds of roofs, five choices of windows, four furnace types and four kinds of air conditioning systems, there are 2,400 possible combinations to choose from.
Ed Crawley is a rocket scientist. A professor at MIT specializing in aeronautics, astronautics and engineering systems, he was working with a team of graduate students designing a mission to Mars in 2009. In space flight, everything impacts everything else. Remember that scene in the movie Apollo 13 when the crew finds out a critical filter is round for one part of the spacecraft but square for another? That’s the kind of stuff Crawley and his team had to deal with every day.
So they designed a computer program called Ekotrope that would help them choose the best solution from the thousands of choices available. Later, when he started designing a home for himself, he asked his architect and his builder, “Who can I consult to figure out how to optimize all the capital investments in the house that had to do with energy utilization? And the answer came back: No one.” That’s when he realized that a slimmed down version of the Ekotrope program might be just the tool he was looking for.
Ekotrope takes into account the prices and operating costs of all the potential components, evaluates their energy efficiency, analyzes local building codes and accounts for all applicable federal, state and local incentives. It then compares all that information to a year’s worth of local weather data. The result is a graph showing how each combination performs in terms of capital costs vs. expected annual expenses for heating and cooling.
The graph contains thousands of dots representing all possible design options but the builder only needs to consider the Pareto frontier—the set of dots at the edges where energy costs, construction costs, or both, are low.
Crawley decided to create a new business also called Ekotrope to market the program to large building companies. Co-founder and CEO Ziv Rozenblum says a typical client ends up choosing a design that’s up to 40 percent more energy-efficient than what he or she would have built without the software’s assistance and saves $1,000 to $3,000 in building costs to boot. “For a company that constructs thousands of homes a year, that’s millions of dollars saved on building costs alone,” he says.
Rozenblum mentions one customer who planned to buy expensive walls that could retain heat during the winter. Ekotrope convinced her to invest in a more efficient furnace instead. “A more energy-efficient furnace will get you the same result as the wall system while saving you 90 percent,” Rozenblum recalled telling her. “We ended up saving her $20,000.” The company’s website includes a free online tool that estimates the cost of complying with current energy efficiency requirements contained in various building codes around the country.
“Everyone knows NASA is at the forefront of innovation and technology, but we don’t always get to see the benefits in other sectors on a day-to-day basis,” Crawley said. “That is why spreading this innovation into new industries is so important and exciting. We can use it to immediately improve our world in so many different ways.”