How does insulation save energy?

Here’s why this home upgrade can cut energy use by up to 45%

Here’s why this home upgrade can cut energy use by up to 45%

It’s true. Insulation is a bit of a buzzword when it comes to home efficiency. 

And, frankly, if you’ve read any of Sealed’s other articles, you know we’re sticklers for insisting on better insulation. 

But that’s for good reason. If you’re looking to conserve energy, an insulation upgrade is one of the best investments you can make.

Why? Is it worth it to insulate your house? And how much energy does insulation save, anyway?

Google has not led you astray. You’ll get the answers to all of the above (and more) in this article. 

Here, we’ll look at how insulation works. 

You’ll get some pointers for deciding whether investing in insulation is worth the cost in your situation.

And we’ll see how much you can expect to save on your energy bills if you do decide to upgrade.

(Plus, you could get high-performance home insulation upgrades at no upfront cost if your house qualifies. Discover how.)

Ready? Let’s hop on in below. (Or use these links to skip ahead.)

illustrated GIF of house diagram showing how insulation and air sealing stop heat loss and energy waste

How does insulation prevent energy loss?

We’re going to talk about how your house is losing energy in the first place—but first, let’s cover what’s supposed to happen in your house. 

Here’s the two-step process of a Perfectly Comfy Home:

  1. The HVAC produces warm air (or cool air!) and circulates it throughout the entire home evenly.
  2. Then the important step: The thermal barrier of a home—that is, the temperature barrier formed by the walls and insulation—keeps that treated air inside the house.

Simple enough, right? 

But that’s not what happens in the majority of American homes (especially those built more than 15-20 years ago). 

Instead, what we often see is the two-step process of a Sad, Uncomfortable House:

  1. The HVAC circulates warm or cold air into the home. (We’ll assume this heated or cooled air is also circulated evenly, though that’s often a bad assumption.)
  2. A huge percentage of that treated air escapes, causing major energy waste—as well as major discomfort to the residents of the home. This air escape happens largely because of—you guessed it—a lack of proper insulation and air sealing, which you’ll learn a bit about in this article, too. (It’s a big reason you’re probably wondering why your heating bill is so high.)

The situation is made even worse by a phenomenon known as the Stack Effect

Don’t recognize the name? You’ve almost certainly heard of it (if not feel it daily in your own house). 

It’s basically an extension of the old heat rises principle most of us learned in elementary school.

The Stack Effect (or indoor-outdoor airflow of your house) is what produces cold drafts in winter and hot spots in summer.

The Stack Effect—a quick refresher

Warm air rises to the top of an under-insulated home—where it escapes because there’s an insufficient insulation barrier.

Meanwhile, since nature abhors a vacuum (1), cold air is pulled in from below to replace the air that’s escaped. 

This causes a very unpleasant circular airflow that moves in, through, and then out of the building—which can lead to extremely uncomfortable temperatures and energy loss.

The Stack Effect (or indoor-outdoor airflow of your house) is what produces cold drafts in winter and hot spots in summer, too.

For a visual of how this works, check out the quick video below:

Essentially, the Stack Effect is like a giant vacuum that sucks all the treated air out of your home. 

And to make matters worse, its effects are even more pronounced if you live on multiple stories or have an untreated attic. (This is why large older homes can be so hard to heat.)

Don’t worry, though—there’s a fix in the works!

Interrupting the Stack Effect—How does proper insulation of home save energy

Interrupting the Stack Effect is pretty simple, in principle: You just need to fix your thermal barrier by upgrading the insulation and air sealing (if your insulation upgrades are done correctly, they usually include air sealing). 

And most importantly? The areas in the attic and around your house’s foundation need expert attention. 

Insulation drastically reduces temperature and air exchange with the outside—and therefore drastically reduces the Stack Effect.

Why focus on the attic and foundation? 

Technically, you could just re-insulate your whole house. But that’s a pretty invasive and expensive home project, and—truth be told—it’s often not necessary. 

Research shows that if you want the biggest bang for your buck, focusing on attic insulation as well as foundation insulation is the ticket (2). (You’ll learn why in a minute.)

And when you think about how the Stack Effect works, that makes good sense. 

Research shows that if you want the biggest bang for your buck, focusing on attic insulation and foundation insulation is the ticket.

If your attic is under-insulated, there’s basically nothing to stop the heat you purchased from escaping your house in winter.

And if the area around your foundation is under-insulated, it’s very easy for cold air (and moisture, too) to get sucked in to complete the Stack Effect cycle.

But, now, an important question, especially if you’re considering multiple home upgrades: Just how much of a difference does insulation really make? 

Quite a large one. And there’s research to back that up.

How much does insulation save on energy bills?

The short answer: A significant amount! Research shows that better insulation results in solid savings. 

For example, a study commissioned by the national insulation trade associations estimated that energy savings ranging from 10–45% can be achieved by air sealing and insulating existing homes. (3)

So if you have a monthly average heating and cooling bill of, say, $300 per month—it’s possible that insulating and sealing your house could reduce what you spend on energy consumption by as much as $165 per month—or close to $2,000 per year. 

But it really depends on a lot of different variables. 

Every house is different, of course—and the energy savings from insulation upgrades can vary drastically depending on:

  • The year your house was built
  • The amount of insulation you already have in place
  • The extent of your upgrades (Is your contractor doing air sealing before they insulate? If not, they should!)
  • The type of insulation you use 
  • What other home improvements you might be doing at the same time. 

The climate in your area matters, too—upgrading a house in Florida will produce very different energy savings than if your house were in, say, Montana. (4)

Want a better idea of how much you could save with home upgrades? Tap here if you’re wondering how to find a home energy audit near me.

So, is it worth the investment to upgrade the insulation in your home? In most cases, yes.

In fact, it’s estimated that 90% of U.S. homes are under-insulated (5).

When you look at the energy savings over the next decade or so, there’s a good chance your insulation upgrade will pay for itself. (As well as make your house a lot more comfortable.)

90% of U.S. homes are under-insulated.

And there’s another important consideration here, too, which is that insulating your home can also extend the life of your HVAC—and even your roof, when attic insulation is done properly

With a better thermal barrier, your heating and cooling system won’t have to work as hard to maintain a comfortable temperature, which means less wear and tear on your HVAC.

And reduced heat loss in your attic means less wear-and-tear on an expensive roof upgrade, too.

 A win all around.

So, if you’re sold on insulation, next comes a pretty important consideration: How should you plan your upgrades? How can you get the most out of your insulation dollars?

What part of a house should you insulate first? Strategies for upgrading your insulation

Okay! It’s time to strategize, and we’ve got three big tips here:

  1. Focus on the attic and foundation
  2. Seal up air gaps throughout your home at the same time
  3. Hire someone who knows what they’re doing

Focus on the attic and foundation

If your objective is to cut energy waste in your house, then you’ve got to insulate strategically to interrupt the Stack Effect. 

And, as we explained above, the best way to do this is by focusing on attic insulation and foundation insulation. These areas are particularly vulnerable to energy loss due to convection, so if you fix them, you’ll have fixed the biggest contributors to the problem.

Seal up air gaps at the same time

To really optimize your home’s energy usage, you need to ensure that your home’s thermal barrier is the best it can be. And that means you should also find and seal up any air gaps in the house (and if your house is like most in the U.S., you likely have a lot of air leaks throughout your home).

Air leakage is a major source of energy waste, and it’s estimated to account for up to 40% of your total heating and cooling energy consumption (6).

So, when you’re insulating your home, make sure that all cracks and openings around windows, doors, electrical outlets, and recessed lighting are closed up, too.

(Learn more about air sealing here.)

Hire someone who knows what they’re doing

Here’s a biggie! Unless you’re an expert, insulating and sealing your home is not a good DIY project. Tap here to read DIY blown-in cellulose insulation to know if its for you.

Insulation can be pretty complicated, and you want someone who knows your climate and can calculate exactly how much insulation you need (as well as the R-value) so that you don’t end up overpaying or getting shoddy work.

(Want to know more about R-value, by the way? Tap here for a quick, simple education on attic insulation types.)

The good news here is that, if your house qualifies, you can get your house insulated and air sealed by experts—for NO upfront cost.

Okay, time for a recap?

Top 3 reasons to insulate (or upgrade your insulation)

Quick refresher! Here’s why you should seriously consider upgrading your insulation.

1. Insulating cuts energy loss to a minimum.

A properly done insulation upgrade—installed by a professional—will likely shrink your energy usage (and extend the life of your HVAC).

2. Insulation makes your house much more comfortable

Here’s the beautiful thing: The upgrades that make your home more efficient are the same upgrades that make it more comfortable.

You’ll be shocked at how much more livable your house is when you reduce the indoor-outdoor air exchange that happens via the Stack Effect.

3. An insulation upgrade can also help with noise reduction

Insulation can be an incredibly effective way to reduce noise within your home. 

Insulation acts as a barrier between the outside world and the interior of your home, effectively muffling noises from nearby traffic, construction sites, or other loud annoyances (like your neighbor’s sweet-but-rowdy terrier mix who loves to bark at squirrels in the backyard).

Get your house insulated—for NO upfront cost

If you’re sold on the benefits of home insulation upgrades—but unenthusiastic about planning (or paying for!) a huge home improvement project—we hear you.

Luckily, all the stress of insulation upgrades vanishes when you choose Sealed for your home upgrades.

Here’s how it works: If your house qualifies for a Sealed energy makeover, you’ll get a free expert energy assessment of your home—and we’ll create a customized plan for your energy upgrades. (You’ll get everything you need and nothing you don’t!) 

After you approve the plan, we’ll hire and vet the best local contractors and manage the project from start to finish. You could even get an energy-efficient heat pump installed while we’re at it. 

And you pay for the work done with a flexible payment option that works best for you. Learn how the payment plan works.

Want to see if you qualify? Tap here.

Insulation FAQs: Common questions about insulation

At Sealed, we receive all sorts of questions about home insulation. Here are a few common ones below:

Don’t see your question here? Talk to us!

How do you tell if your house is poorly insulated?

Honestly, your comfort is a great guide here. If you’re feeling a bit chilly in the winter or too hot in the summer, it’s likely that your home may not be properly insulated.

Signs of poor insulation also include:

  • High utility bills
  • Increased condensation on walls and windows
  • Inconsistent temperatures throughout different rooms (drafty house, anyone?)
  • Crumbling insulation found in the attic or outdoors around your house
  • Attic joists peeking out over cellulose insulation

If any of these issues sound familiar, it might be time to get that energy audit scheduled.

Getting the right amount and quality of insulation can make all the difference when it comes to staying comfortable. Tap here to discover how long insulation lasts.

Can you over insulate a house?

Absolutely! In fact, it’s important to make sure your home is not over-insulated as this could cause moisture and heat build-up that can be detrimental to the health and comfort of your home.

(How could inexperienced or DIY home insulation make your issues worse? Check out this vintage YouTube video called Grandma’s House: A Tale of Weatherization supported by for an entertaining look.) 

The simplest way to avoid this issue? Hire a professional (or let us do the hiring for you.)

Why are old houses not insulated?

Older homes usually weren’t built with insulation in mind, since insulation wasn’t as widely used in the past (or even available or required in some circumstances!). Fiberglass insulation wasn’t even invented until the 1930s. (7)

The good news here is that, while your home may not have been insulated when it was first built, it’s not too late! You can add insulation now to save energy and ensure a more comfortable living space. (Get insulation upgrades on your old house—for no upfront cost.)

January 20, 2023