But with the decision to return to Irvine, the organizers have raised the stakes by going all-in for solar electricity. This is the fundamental paradox of the Solar Decathlon.Īs I wrote in The Solar House, the Solar Decathlon has always been oriented to the promotion of PV systems, and it has always endured criticism for failing to reward passive strategies. Why not hold the contest in Minneapolis a month later? Perhaps because passive solar heating implies the need for thermal mass, which is contradictory to the need for the houses to be lightweight and transportable. To design an 800-square foot house in Irvine that will use net-zero energy for a week in October is frankly not very difficult. Most of the places in the US are not like Irvine in October they have significant heating demands that can be reduced through passive solar design. I'm a big supporter of solar electricity, to be sure, but passive solar heating ought to be central to the challenge and to the definition of a 'solar house' and a 'net-zero' house. In Irvine in October, the average temperature is 64 ˚F, practically room temperature! (In Washington, DC in October, the average temperature is cooler, though still mild at 59˚F.) This is a significant and disappointing decision because it confirms that the contest is about solar electricity, not solar heating. Traditionally, the Decathlon was held in Washington, DC, but moved to Irvine for the 2013 contest. This week the Department of Energy announced that the 2015 Solar Decathlon will again be sited at the Orange County Great Park in Irvine, California ( link).