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There is no need to change the colour of the roof. Good reflectors of heat are also bad emitters of heat. A shiny surface saves money summer and winter.
How about louvered roof panels -- black on one side, white on the other -- like a billboard switching ads. Pull a lever to change 'em up. Could be done on a daily basis, as needed.
Funny. I've been thinking about the dark roofs lately. In Oklahoma it's been over 100 for the past 47 days.
Re: Michael and Bernie's changing reflective/absorbing roofing venture. I. Want. Stock. (now!)
Cool roofs happens to be my field, so it's fun to see it in Doonesbury. The short answer to Mike's question is that the summer cooling savings associated with substituting a white roof for a black roof are much greater than the winter heating penalty, primarily because in cold U.S. climates a roof receives about three to five times more daily sunlight in summer than in winter. (In winter the sun is low, the days are short, and the sky tends to be cloudy.) Hence the annual net energy cost savings (annual cooling energy cost savings - annual heating energy cost penalty) is positive nearly everywhere in the U.S.
There are three further issues with switchable roofs. 1) The small magnitude of a white roof's annual heating energy cost penalty limits the potential benefit of switchable roofing. That is, a switchable roof would save more energy than an always-white roof, but not a lot more. 2) The added benefit of a switchable roof is nil when the roof is under snow, because all snow-covered roofs are white. 3) The switching method would have to be electrochromic, rather than thermochromic, because a thermochromic roof will tend to suffer from a negative feedback that drives it toward gray. That is, a thermochromic switchable roof will darken as it cools, but getting darker will make it warmer, which will make it lighter, which will make it cooler, and so on. (For more about cool roofs, including maps of energy savings and penalties, click here.)
Hey, Mike just stole my idea!
Today's strip reminded me of the Skytherm System developed in California in the 70s. Not exactly what your cartoon suggested, but has the same effect. It is located in Atascadero, California (approximately 12 miles north of San Luis Obispo). When outside temperatures were in the triple digits for extended periods, the homes internal temperature was in the high 60s. Thanks for keeping the interest up in energy saving by passive means.
I thought the idea of painting roofs white was to diminish their impact on global warming not on air conditioning bills. And heat rises instead of sinks, so I imagine the impact on heating bills in the winter would be negligible. There's far less sunlight to be absorbed during the winter, especially in the colder, northern regions, and in any case nature herself often ends up painting roofs white -- with snow. It looks like GBT's chasing not even a red, but a dull brown herring.
Us Mainahs have this problem licked. It's called snow!
Re. today's strip about painting roofs white: Black roofs absorb heat from the sun in the daytime, but they radiate heat away into space at night. The black roof will lose more heat at night than it receives during the day during the winter. Painting a roof white is like adding insulation, except that it only works for radiative heat transfer. There are times when insulation works against you also, but on balance, it's better to have it than not. Of course, if Bernie can develop a roof that changes color between day and night, you'd have a winner.
Today's strip perfectly captured the two steps of an inventive process, and a key reason why it is sometimes so hard to convince non-inventors that a genius invention is "non-obvious." Given the progress of the America Invents / Patent Reform Act of 2011, this strip is quietly timely.
The Flashback strips from years ago often take me back -- they provide a flavor and texture, well known at the time but long since forgotten. The recently-featured 30-year-old conversation among Mark (as radio host), a guest who counsels vets, and a Vietnam War vet caller reminds me so strongly of what it was like back then. Americans didn't realize how badly many of them treated us, and PTSD didn't even have a name yet. Long time gone.
I see where you're going with Jeff's Mom considering reentering the job market after a long break from her career. I'm in the same spot. Here is the reality check. No matter how much experience or ego one may have, step out of line, good luck gettin' back in! That's the up-shot of my experience at the age of 53 returning to the job market. There are no spaces open. Stay true to that American nightmare and I'll stay true to reading you everyday. Deal?
Re. MY GENERATION. Everyone keeps saying it, but this is not the worst job market since the Great Depression. The job market of the 1970s and early 1980s (when most of the Baby Boomers enetered the workforce) was much worse than today.
Wow! It's awfully hard to criticize our kids when they are just taking their cues from their parents. "The apple doesn't fall far from the tree." When Jeff realizes that his mom is fantasizing about a job that doesn't exist they suddenly have a lot more in common than either would previously like to have admitted. But when it comes down to it the most successful people in this world are the ones who were willing to dream, fantasize, and then create the job that best defines them. I suspect this is something that earlier generations have realized on a more conscious level than does the current one, and the real challenge in parenting today lies in helping our kids connect with this process of making one's future for oneself.
Jeff's parents need to realize that he is, indeed, taking his cues from them; he is just stuck between the fantasizing and the leap of faith required to make that dream into a reality. Perhaps this epiphany will finally lead Jeff to find a way to live his dream job, and help his parents to realize that they do have an impact on his life course even at this later stage.
Re. ABOUT TEXTING. I'd sit down with Maryjane for a chat over coffee any day. Texting? Phooey! Genuine warm-blooded communicating -- real conversation in real time -- is being displaced. Add to that the fact that so many are constantly plugged into overly loud music piped from their MP3 players through ear buds. What's it mean? It means we're heading toward a time when huge swathes of the population will be so hearing impaired that they won't have any choices left. Texting will be their only option.
Some people in my generation are getting a little tired of baby boomers telling us that we're lazy or immature for not having good jobs and houses, when we've come of age in the worst job market since the Great Depression. Jeff is Jeff, but I'd like to see a more realistic example, like smart, accomplished Alex struggling for months to find a reasonable job.
I'm lovin' the Elizabeth Warren narrative already, GBT. Now that's the way to keep it timely and topical -- just like the good ol' days. You go, man!
I like that Jeff obviously cares enough about his mum to pretend to be interested in her thoughts about her going back to work. Although obviously his doing so also is a great worry.