On 2016-12-20 08:38, Paul Eggert wrote:
Brian Inglis wrote:
Now question is: Do we want to stay on Mountain Standard Time all year, do we want to go to Mountain Daylight time? As it happens, a week ago Nicholas Rivers of the University of Ottawa published the best work I have seen on the subject of DST-based energy savings in Canada. Rivers found that in Ontario, DST reduces electricity demand 1.5% during the couple of weeks after the transition (he studied transitions, not year-round consumption). Like Havranek et al., which I cited a couple of days ago, Rivers hypothesizes that DST-based electricity savings is most pronounced at high latitudes, and notes that he does not estimate the costs of DST (e.g., due to increased traffic accident rates).
Havranek et. al. I found a wee bit annoying as it made it clear that there was no benefit at lowest and highest latitudes, but did not provide sufficient data on numbers and locations to nail down the "Goldilocks" latitudes where it does provide a benefit to say 35-50. My own experience here is that the dates are far enough from the equinoxes that we drive to and from work into the sunrise and sunset for two months instead of one, so what we lose in spring we gain in fall, but still don't see daylight at home except April to September, and the days are short enough at the changes that energy consumption likely depends more on weather than time. Given that the UK is also all above 49N I can sympathize with the Scots, most of whom live at or above 55N, complaining about the time change impact.
Rivers N. Does daylight savings time save energy? Evidence from Ontario. 2016-12-13. SSRN. https://ssrn.com/abstract=2772048 Cash C. Spring forward, fall back ... screw up? Reconsidering Alberta's clock revolt. National Post 2016-12-19. http://news.nationalpost.com/full-comment/colby-cosh-spring-forward-fall-bac...
Most of the eastern Canadian population is just north of the border on the Great Lakes and St Laurent, well south of the 49N western border, nearly 10 deg S of western cities, uses a lot more domestic electrical heating and air conditioning with probably lighter insulation, than western areas which use electricity mainly for industrial processes and air conditioning for commercial premises with heavier insulation which helps in both winter and summer extreme temperatures ("it's a dry heat|cold"). Rivers seems to show that electricity demand is most highly correlated with high temperatures and presumably air conditioning load, possibly because he seems to be using Toronto as a proxy for Ontario, despite its size, for some variables, and does not seem to control for the reduction of demand by high costs driving dependent industries out of province, generation facilities going offline for maintenance reducing supply, wind generation providing supply greater than demand driving prices negative, commercial and industrial load shedding and peak to off peak consumption shifts by heavy users during high demand and cost, and contingent generation facilities brought online to take advantange of high demand and prices i.e. the drivers of consumption. For tariff reasons, heavy lighting consumption is tracked separately from domestic, retail, light and heavy commercial, and industrial users, so it should have been possible to look at consumption and calculate differences for each group, and look at factors behind differences more closely. I find it difficult to believe that very predictable lighting demands would be so heavy as to allow a 1.5% reduction of overall provincial demand without other factors being in play - I could believe it for Toronto during clear sunny weather, but across a province spanning the Great Lakes and N to Nunavut in early spring, I have grave doubts as to the likelihood of that being possible without further checks on the assumptions. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada