In a perfectly competitive market, the price of a product is given by its minimum average total cost of production.  The lower this is, the lower the price.  Technological advances have reduced the costs of operating a fridge, air conditioner, washing machine etc… etc….  Consumers will buy more of them and consume more electricity and produce more greenhouse gases.  How much more depends on the elasticity of demand. If elasticity is high, energy consumption may go up so fast that it results in greater resource depletion with greater energy efficiency. This is basic economics and was known in the nineteenth century.   It is known as the Jevons paradox and is the topic on an article in the New Yorker (subscription required):

In 1865, a twenty-nine-year-old Englishman named William Stanley Jevons published a book, “The Coal Question,” in which he argued that the bonanza couldn’t last. Britain’s affluence and global hegemony, he wrote, depended on its endowment of coal, which the country was rapidly depleting. He added that such an outcome could not be delayed through increased “economy” in the use of coal—what we refer to today as energy efficiency. He concluded, in italics, “It is wholly a confusion of ideas to suppose that the economical use of fuel is equivalent to a diminished consumption. The very contrary is the truth.

Jevons is now known more as a utilitarian and one of the founders of mathematical economics.  Who knew he combined the practical with the theoretical?