Chris Buchanan and Robert Lawless want to make buying a heating system, windows, or solar panels almost as easy as buying a plane ticket online.

They have formed a start-up, ­Enmojo, to act as a price-comparison website, similar to Kayak.com and Priceline.com but for home energy products. Homeowners key in the relevant information, and Enmojo returns a handful of price quotes from providers qualified to do the work.