Your thermostat says it’s nice and cool in your home, but one room still feels uncomfortably warm. Let’s explore how windows, maintenance and sun exposure affect how hard your air conditioner works.
It’s the middle of summer… and every time you walk into that one room, it’s ALWAYS too hot. What the heck is going on?
You’re not alone, it’s a common issue. Parts of your home might feel perfect, but it’s just not consistent as you move around the house.
Your Thermostat Says 73… So Why Does One Room Feel So Hot?
Windows may not heat or cool your home like the HVAC system, but they do affect how easily heat moves between the inside and outside of your home, how much heat flows in, and how hard your HVAC system works to keep things comfortable.
Understanding how windows work might help you identify why certain rooms are uncomfortable and what you can do about it.
Check out Part One in our glass series:
The Weirdly Interesting Thing about Glass in Replacement Windows
How Heat Moves Through a Window
Heat can affect your home through a window in three primary ways:
- heat from the sun that passes through the glass,
- heat that transfers in through the frame,
- and air from outside that flows in through gaps in/around the window.
These processes can happen at the same time.
For example, a west-facing window may be absorbing intense afternoon sun that’s shining right on the glass. Rooms on that side of the house might feel substantially warmer, even though the windows are exactly the same throughout the entire home.. especially if it isn’t shaded by landscaping or overhangs.
That’s probably where the air conditioning struggles to keep up the most.
Or perhaps you still have the original aluminum single-pane windows on your home…. They may only have a single coating of low-e. They also don’t have the gas insulation you get with double-pane windows, and may not have thermal breaks to prevent heat transfer. Whatever heat is absorbed by the frame on the exterior metal frame could be flowing right through to the frame on the inside of the home.
…where it radiates heat all day long, even into the night.
Maybe the caulking was never replaced, too, so it’s bubbled up and cracked on a few of the windows, letting even more heat into those rooms. Combined? It’s a perfect storm, leaving one room significantly warmer than another.
The amount of heat involved depends on the window and how well it’s maintained, but other factors can cause certain rooms to struggle more than others—such as where it is located, how much direct sun the window receives and how well it was installed.
Uneven temperatures can be influenced by multiple things, which explains why it can happen with old AND new windows. It might even have nothing at all to do with the windows.
1. Heat From the Sun Passing Through the Glass
Solar heat gain is often the biggest issue in Phoenix, especially on the west side of a home. Today’s modern windows block most of it, so you might feel a small amount of warmth through even the highest performing windows available.
Real heat is an issue, though.
Look for:
- A room that gets hotter as soon as direct sunlight hits the windows
- Large windows or patio doors with little exterior shade
- Blinds or curtains that feel warm to the touch
- Flooring, furniture or fabrics fading near the glass
- Older glass with limited solar heat protection
If closing the blinds makes a noticeable difference, sunlight passing through the glass is probably contributing.
Exterior shade can help, but older windows may still allow substantially more heat into the home. If the problem is severe, it’s a good idea to consider replacing them. Modern technology has greatly improved in the last decade or so, and today’s windows are far more energy efficient.
If you have this issue with new energy-efficient windows, clean the glass to be sure the window coatings can work efficiently, then feel for heat on the inside of the glass again. You can also compare the problem with other windows that have similar sun exposure. If the interior glass feels substantially hotter or suddenly performs differently, it may be worth contacting the installer to check the glass unit for seal failure.
2. Heat Transferring Through the Frame
Certain types of window frames can absorb quite a bit of heat on the outside of the frame, and allow some or all of it to travel right through to the interior frame. When that happens, heat radiates into the home.
Look for:
- Frames that feel unusually hot to the touch from inside the home
- Older aluminum frames without modern thermal improvements to reduce conductivity
- Heat lingering near the window after the direct sun has moved away
Aluminum conducts heat more easily than vinyl, composite or fiberglass windows, even if they are new. This will influence how the area around the window feels inside your home.
3. Hot Air Entering Through Gaps
Even a good window can struggle if hot air from outside finds its way in.
Check for:
- Cracked, bubbled or missing caulking on the exterior
- Worn or flattened weatherstripping
- Windows that don’t close or lock tightly
- Visible gaps around the frame
- Dust collecting along the interior window sill
- Movement of warm air near the opening
Some of these problems may only require maintenance. Others may point to an installation issue, a home that’s shifted on its foundation, or a window that’s no longer fitting properly in the opening.
If you know who installed the windows, feel free to contact them for assistance, or a quick check that no warranty issue might be needed.
4. The Problem May Not Be the Windows
If the room stays hot even when the windows are shaded, something else may be contributing.
Check for:
- Closed or blocked air vents
- Weak airflow compared with other rooms
- Leaky, damaged or poorly sized ductwork
- Inadequate attic or wall insulation
- Heavy roof exposure above an upstairs room
- Air leaks around doors, outlets or other openings
Timing can provide a useful clue. If the room heats up when sunlight reaches the windows, the windows are probably involved. If it stays uncomfortable around the clock, then airflow, insulation or the HVAC system may deserve a closer look.
If you are an SRP customer, be sure to check their website for a free virtual home audit, or discounted in-person assessment from a third-party provider.
Sometimes It’s More Than One Thing
Uneven temperatures usually don’t come with one perfectly obvious cause.
It might have multiple issues, with each problem adding a little more heat until the room becomes much harder to cool than the rest of the house.
Start with the easiest clues: if the glass and/or window frame feel hot from inside the home, what time of day the room gets hot, whether shade helps, and whether you can feel air around the window.
One or two of these alone might be enough to tell you whether the windows are causing the problem, contributing to it or simply getting blamed for something happening elsewhere in the home.
Think it’s your windows? DunRite is happy to come take a quick look if you’re a homeowner in the Phoenix Metro area. Head over to our Obtain a Quote page, and we’ll call you right back during business hours.
