I too doubted the assertion that it's easier to cool in a warm climate than it is to heat in a cool climate. So I compared Stockholm, Sweden to Phoenix, Arizon

I too doubted the assertion that it's easier to cool in a warm climate than it is to heat in a cool climate. So I compared Stockholm, Sweden to Phoenix, Arizona USA. Sweden averages about 4,000 heating degree days, while Phoenix averages slightly more cooling degree days (4,600). Therefore, takes about 15% more heating/cooling power to live in Phoenix than in Stockholm. Of course, a gas furnace is quite efficient at turning hydrocarbons into heat and CO2. Some furnaces turn 96% [1] of their input gas into heated air, but average is probably closer to 80%. This number could be tempered somewhat by gas transmission loss, in some cities as high as 10% [2]. So, overall, gas furnace heating is maybe 72% efficient. On the other hand, using the same gas, a combined-cycle gas turbine generate is at most 62% efficent [3]. Then there are electricity transmission losses (pretty minor at 6.5%) [4]. However, an A/C unit uses the electricity as a heat pump, which can actually move MORE heat energy than is used to operate the pump. Impressive! A reasonably-efficient A/C unit has a SEER rating above 10, which gives it a Coefficient of Performance (ratio of heat energy pumped to heat energy used) of around 3. [5] This means that it's at least twice as energy-efficient to cool your house in Phoenix as it is to heat your house in Stockholm, if you insulate your house equivalently. I suspect many in Phoenix (or LA, or other hot climates) don't insulate thoroughly, though. [1] https://www.angieslist.com/articles/what-do-furnace-efficiency-ratings-mean.htm https://www.angieslist.com/articles/what-do-furnace-efficien... [2] http://www.sourcewatch.org/index.php/Natural_gas_transmission_leakage_rates http://www.sourcewatch.org/index.php/Natural_gas_transmissio... [3] https://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_CCGT_plants https://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_C... [4] https://en.wikipedia.org/wiki/Electric_power_transmission#Losses https://en.wikipedia.org/wiki/Electric_power_transmission#Lo... [5] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.h...