How Does Insulation Keep Your House Warm? (Helpful Guide)


The U.S. Environmental Protection Agency calculates that you can save up to 11% of your energy costs if you insulate your home. Insulating our homes goes a long way in modulating the loss of heat, especially in the winter months. But you may have wondered how insulation manages to keep your home warm. Does the insulation itself generate heat?

Home insulation retains the warmth of your inner space by slowing the transfer of heat from your home outdoors. This is significant during winter when the surrounding is cold and naturally draws heat from an enclosed space like your home. By preventing hot air in your home from leaving, your insulation “retains” the warmth of your home. So, home insulation doesn’t independently create heat.

Having established this, it is not proper to laden your entire home with just any insulation material in the colder months. You have to know which type of insulation works best for keeping your home warm. You also have to be informed of the strategic locations within your home where you should install home insulation.

These are some of the critical nuggets this piece feeds you.

How Does House Insulation Help in Winter?

Winter can be really cold, especially during the excruciating months of December to February. This is where your home insulation becomes critical in sustaining the warmth in your home.

But as we earlier clarified, home insulation is not a furnace that generates heat on its own. In the winter months, it is commonly freezing outdoors.

Heat naturally flows from hotter areas to colder areas. This means that the cold outside will be aggressively sucking warm air from inside your home.

This would continue until there is no difference in temperature outdoors and indoors. Let us assume that your garage, attic, and basements are unheated.

They will drag the heat from your home, as explained. What your house insulation does is to create a barrier to the transfer of heat from inside out.

The capacity of your home insulation to keep your home warm depends on its R-value. The R-value – which here is the thermal resistance – typifies the ability of your insulation to impede the loss of heat outdoors via conduction.

Factors like the insulation density (and its thickness) determine its R-value. The older and moister your insulation, the poorer its capacity to keep your home warm in winter.

There are strategic locations in your home that you should insulate to prevent the rapid loss of heat during winter.

Your attic is one of the most notorious outlets through which heat escapes from your home during the cold months. Hot air – by its nature – rises up.

This means when it comes to attic or ceilings, and the insulation doesn’t curtail it, it would escape outdoors.

If you have unfinished attic space, ensure that you properly insulate over the floor joists (and between them as well) to shut off the living spaces below.

Also, make sure your attic access door is insulated.

Your exterior walls are another critical destination that needs insulation. Focus on the walls separating your garages (if unheated) and the part of your home where you stay.

Similarly, insulate the walls separating your living space from unheated storage areas. If you have vented crawl spaces and other unconditioned spaces, ensure you insulate the floors above them.

Band joints are another vital place you shouldn’t forget to insulate. If you don’t mind, we recommend going as far as to caulk your doors and windows.

How Much Warmer Does Insulation Make a House?

This is one cunning question we get asked a lot. The truth is, there is no definitive amount by which home insulation would warm up your home.

A lot depends on the prevailing climatic conditions and the build of your home. Let us assume you are insulating an old school home that lacks insulation in the attic or walls.

Insulating the attic with R-38 insulation and the walls with R-15 insulation can keep the home sustainably warm enough to save 50% on gas bills.

What is the Best Insulator to Keep Things Warm?

The market is flooded with insulation materials, all proclaiming to keep your home warm as hell. Well, we did our investigations, and these are the best insulation types (we will avoid mentioning brands) that you can get to keep things warm in your home.

Fiberglass Insulation

Inevitably, fiberglass insulation is the first type of insulation that comes to mind if you live in colder climes and desire to keep your home warmer.

In cold climes, you should go for loose-fill fiberglass insulation. This variant boasts a mouthwatering R-Value of 60.

This will sustainably retain heat in your home. The better part?

Loose-fill fiberglass lasts long, retaining its insulating capacities longer than many other types of fiberglass insulation. 

This insulation doesn’t decay, and you wouldn’t need to treat it with fire-retardant chemicals either.

On the greener side, it is more environmentally friendly and even resists the invasion of insects or mold.

Blown-In Insulation

If you want to go for blown-in insulation, we recommend sticking with blown-in cellulose insulation. It doesn’t boast the impressive R-values of loose-fill fiberglass, but it doesn’t fall flat either, boasting commendable R-values of 49.

This works well in cold regions, especially when deployed in wall cavities and unfinished attic floors.

Spray Foam Insulation

Spray foam insulation typically comes in liquid and can be sprayed on the sections of your home that you need to be insulated.

The way it works, the foams caulk upon settling, effectively creating an air barrier (as it expands) that prevents heat from leaving your home.

Compared to batt insulation, spray foam has a superior R-value. For an inch of spray foam insulation, you can get as much R-6.5 insulation.

Such superiority doesn’t come free, as spray foam insulation costs way more than batts insulation. The former also requires professional installation.

Polyurethane Foam 

Polyurethane foam is one of the latest emerging insulation types you can use for colder climes. Its R-value is not bad either, presenting R-6.3 per inch.

Its fire resistance and lightweight nature make it a favorite for spraying on your roof and walls. It repels pests with some commendable soundproofing properties as well.

Does Insulation Keep the Air In or Out?

It all depends on how you installed it and the prevailing climatic conditions. The underlying factor is the direction of the flow of heat.

If your home is hotter than outside, typical of the winter months, the hot air will attempt to flow from inside your house out.

Your insulation will, in such situations, keep the air in. This makes your home warmer.

Now, if in the summer months, the outdoor temperature is typically higher than indoors.

Since heat naturally flows from hotter areas to colder areas, the hotter air outside will attempt to move inside your home.

In such situations, your home insulation will keep such hot air out. This makes your home cooler.

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