Eli5 Does underfloor insulation make houses hotter in Summer?

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Been advised it might be good to get this in my house at it’s freezing during Winter. But it’s such a hot house in Summer. So will it make it even hotter in Summer?

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8 Answers

Anonymous 0 Comments

What is underneath the floor?

If it’s directly on the foundation, then maybe. -/ you can’t directly sink heat into the ground.

But if there’s a crawl space underneath the floor, then that crawl space is also gonna get hot in the summer, like it gets cold in the winter, and could be letting heat into your house.

Anonymous 0 Comments

Insulation doesn’t just make your house warmer. It serves as a type of barrier to keep the outside temps from coming inside. Proper insulation will keep you warmer in winter and cooler in summer (assuming you have heat and air conditioning).

Anonymous 0 Comments

What is underneath the floor?

If it’s directly on the foundation, then maybe. -/ you can’t directly sink heat into the ground.

But if there’s a crawl space underneath the floor, then that crawl space is also gonna get hot in the summer, like it gets cold in the winter, and could be letting heat into your house.

Anonymous 0 Comments

Insulation doesn’t just make your house warmer. It serves as a type of barrier to keep the outside temps from coming inside. Proper insulation will keep you warmer in winter and cooler in summer (assuming you have heat and air conditioning).

Anonymous 0 Comments

Insulation doesn’t make your house warm. It’s a thermal barrier that separates the inside of your house from the outside environment to reduce heat transfer.

So in the summer when it’s hot outside and cool inside your house with the AC on, the insulation will minimize the heat from outside trying to get in. And in the winter when you have the heat on, insulation will minimize the heat trying to escape.

A sort of unrelated note, if you live in an area that gets snow in the winter, you can tell who has poor ceiling insulation by looking at the snow on the roof. Poor insulation allows the heat from inside the house to escape, and melt the snow on the roof. So oftentimes when you see a house with little snow on their roof, while all the neighboring houses are covered in snow, they most likely have bad insulation. This leads to an increased cost of energy bills in an attempt to keep a constant indoor temperature while combating the heat lost to the environment.

Anonymous 0 Comments

Insulation doesn’t make your house warm. It’s a thermal barrier that separates the inside of your house from the outside environment to reduce heat transfer.

So in the summer when it’s hot outside and cool inside your house with the AC on, the insulation will minimize the heat from outside trying to get in. And in the winter when you have the heat on, insulation will minimize the heat trying to escape.

A sort of unrelated note, if you live in an area that gets snow in the winter, you can tell who has poor ceiling insulation by looking at the snow on the roof. Poor insulation allows the heat from inside the house to escape, and melt the snow on the roof. So oftentimes when you see a house with little snow on their roof, while all the neighboring houses are covered in snow, they most likely have bad insulation. This leads to an increased cost of energy bills in an attempt to keep a constant indoor temperature while combating the heat lost to the environment.

Anonymous 0 Comments

The surface has a bunch of temperature that varies depending upon whether the sun is up or not, what season it is, etc.

Get a few feet underground a few feet and we don’t have direct radiation from the sun, or convection from moving air–conduction dominates. It just so happens that conduction is the slowest form of heat transfer. It’s slow enough that underground the temperature maintains a constant steady state temperature that doesn’t vary much (if all) from day to night and/or from summer to winter. Underground you get a temperature that is approximately the yearly average of temperatures on the surface.

Let’s look at Quito since it is near the equator so it has a rather constant high and low temperature each day. Day and night are about the same length as well. It has an average high of around 67F and an average low of around 48F. Taking the average we get 57.5. According to a web page I found, the ground temperature in Quito is around 60F–pretty close to 57.5.

Since the temperature underground is roughly constant AND approximates the average over the entire year, it will most likely be colder than the surface temperature on a hot summer day. This means that heat would tend to flow from the house into the ground. If you insulate your floor from the ground you prevent this transfer of heat into the ground leaving the house warmer than if you’d allowed the heat to flow into the ground.

Anonymous 0 Comments

The surface has a bunch of temperature that varies depending upon whether the sun is up or not, what season it is, etc.

Get a few feet underground a few feet and we don’t have direct radiation from the sun, or convection from moving air–conduction dominates. It just so happens that conduction is the slowest form of heat transfer. It’s slow enough that underground the temperature maintains a constant steady state temperature that doesn’t vary much (if all) from day to night and/or from summer to winter. Underground you get a temperature that is approximately the yearly average of temperatures on the surface.

Let’s look at Quito since it is near the equator so it has a rather constant high and low temperature each day. Day and night are about the same length as well. It has an average high of around 67F and an average low of around 48F. Taking the average we get 57.5. According to a web page I found, the ground temperature in Quito is around 60F–pretty close to 57.5.

Since the temperature underground is roughly constant AND approximates the average over the entire year, it will most likely be colder than the surface temperature on a hot summer day. This means that heat would tend to flow from the house into the ground. If you insulate your floor from the ground you prevent this transfer of heat into the ground leaving the house warmer than if you’d allowed the heat to flow into the ground.