The upstairs room that never cools down
If you own one of the older bungalows or foursquares around Rountree, Delaware Town, or the streets east of Glenstone, you already know the pattern. The first floor cools off fine on a July evening. The upstairs bedroom stays warm until midnight, sometimes later. You've probably blamed the window unit, or the ceiling fan, or just chalked it up to "old house, hot roof." It's rarely any of those things on their own. It's usually a combination of plaster walls that hold heat, little to no insulation in the knee walls and attic floor, and a duct system that was never designed to move the air a modern central system wants to push.
Springfield summers run humid as much as they run hot. We don't get the dry desert heat that a swamp cooler or a single window unit can shrug off. We get the kind of mid-80s, 70-percent-humidity stretch that sits on a house for weeks at a time. A 1920s house built for cross-ventilation and ceiling fans wasn't built to fight that kind of air, and retrofitting central cooling into it means working around plaster, not through it.
Why nobody wants to open the walls
Plaster and lath were built to last, and in most of these houses they have. Original plaster walls are often straighter and more solid than anything built with drywall after 1960. Tearing them out to run new ductwork is expensive, messy, and in a lot of cases unnecessary. The real question isn't whether the walls need to come out. It's whether the house has a path for air that doesn't require it.
Many of these homes already have a chase somewhere, an old chimney that's no longer in use, a closet stacked on top of another closet, a gap behind a stairwell. These are the places where small, flexible ducting can run floor to floor without touching a single lath strip. Finding them takes someone who's walked through a lot of houses from this era in this town, not a generic floor plan guess.
More on this from Cooling A 1920S House Without Tearing Out The Plaster.
What you can check before you call anyone
Walk your attic with a flashlight on a cool day. Look at the insulation depth over the bedrooms specifically, not just the main attic space. In a lot of these houses, the areas over additions or enclosed porches got skipped entirely when insulation was added decades ago, and that's exactly where the heat problem concentrates.
Check your window units and any existing vents for where the cold air is actually landing. If a vent blows straight down into a stairwell or an opening with no distribution, you're cooling air that leaves the house before anyone feels it. Also look at your attic access hatch. A lot of 1920s houses have a hatch with no weatherstripping and no insulation on the cover itself, which quietly dumps hot air straight into the hallway below it all summer.
Where this stops being a weekend project
Sealing an attic hatch, adding insulation over an accessible attic floor, these are jobs a reasonably handy homeowner can do in an afternoon. Figuring out how to deliver cooled air to a room that has no existing duct path, without cutting into plaster or losing closet space, is a different kind of problem. That takes someone who can look at the house's actual structure, find where a chase or a soffit will let a duct run hidden, and size the equipment so it's not oversized for a house with bad duct runs and undersized for actual humidity load.
This is also where a lot of well-meaning fixes go wrong. A contractor who treats a 1920s Springfield house like a 2005 subdivision house will often recommend equipment sized off square footage alone. That ignores the plaster's thermal mass, the leaky old windows, and the fact that east-facing rooms in these neighborhoods get hit hard by morning sun with little shade from mature trees that may have come down over the decades.
The long view for an older house
None of this means replacing the character of the house. It means working with what's already there, the chases, the old chimneys, the unfinished spaces behind closets, and treating the plaster as something to route around rather than something to fight. Done that way, a 1920s Springfield house can cool as evenly as anything built last year, without a single crack in the ceiling to show for it.