An expert from the Rocky Mountain Institute argues that solar energy may be more glamorous, but efficiency, the old workhorse of green buildings, remains a winner, just not in all cases.
“Efficiency first” is the mantra in green and net-zero buildings; you always do energy efficiency first and then cover the remaining balance of energy needs with renewables such as rooftop solar. This is almost a moral code for green buildings. But in today’s world of rapidly falling costs for renewables, the tipping point between cost-effective efficiency and solar is shifting.
The cost of saving energy through efficiency measures has typically been three to five times lower than any of the renewable sources of energy. Efficiency, as a bundle on a project, typically costs $0.00–0.02 per kWh. Solar-generated electricity has come from $0.20 or more per kWh down to $0.07–0.15 per kWh. And costs are expected to drop a further 25 to 50 percent in the coming few years. We have found that the most-expensive efficiency options—adding another pane of glazing to the windows in a mild climate, daylighting basement spaces, using complicated and sometimes unreliable control systems to harvest the last bit of energy—can’t compete with the new lower cost of solar. Inching incrementally toward deeper efficiency gets more expensive per kWh of energy saved. But is piling on more solar always the best solution?
Read the rest of the article at http://blog.rmi.org/blog_2015_09_01_in_age_of_cheap_solar_does_efficiency_still_matter