I live in a historic neighborhood in the heart of Washington, D.C. It’s not historic in the sense that anything especially important happened here — certainly not in the modest rowhouses that make up the bulk of the neighborhood. What “historic” means, here and in cities across the country, is that this is a neighborhood where buildings are not supposed to change. The law says window frames on Capitol Hill must be wooden, or something that looks very much like wood. If a front door has two parts and opens down the middle, it cannot be replaced by a single door that swings open from the side. If the house was built two stories tall, it must remain two stories tall — unless the addition can’t be seen from the street. Humans don’t like change, so it’s not surprising that historic preservation laws have become quite popular. There are now more than 2,300 local historic districts across the United States, and I know many people who would like to have their own neighborhood frozen in time. But historic preservation comes at a cost: It obstructs change for the better. And while that price is generally invisible, it is now on public display because of the city’s efforts to prevent Washington homeowners in historic neighborhoods from installing visible rooftop solar panels. As you may have heard, Earth is getting hotter because we’re burning too much carbon, and one small way people can reduce their use of carbon is to tap the sun for electricity. I haven’t taken a poll, but I’m prepared to wager most residents of Washington’s historic districts agree that climate change is caused by humans and that we really ought to do something about it. But the mandarins of historic preservation regard allowing people to install rooftop solar panels with the kind of horror they usually reserve for anachronistic window frames. “I applaud your greenness, and your desire to save the planet. And I realize that we are in crisis, politically as well as sustainably,” Chris Landis, an architect who sat on one of the boards that pass judgment on proposed changes to Washington homes, told a homeowner in October who had the temerity to request permission to install 12 front-facing solar panels on his own roof. “But I just have this vision of a row of houses with solar panels on the front of them and it just — it upsets me, as somebody who’s supposed to protect the architectural fabric of a neighborhood.” Mr. Landis and I apparently don’t share a sense of the sacrifices that may be required in a crisis. As the petitioner, Steven Preister, put the matter to Mr. Landis and his colleagues: “If we do not change and loosen these standards, will the district be habitable in 100 years?” Good question! The board, however, decided it was more important to keep Mr. Preister’s roof looking as it did 100 years ago.