4 Top Reasons Your House’s Colder than the Outside (+FAQs)

A house that stays cool in summer is a blessing in a hot country.

But what if your home is uncomfortably cold, even in the summer heat?

why is my house colder than outside in summer

Why Is Your House Cold in Summer?

If the inside of your house is uncomfortably colder than the outside under the summer sun, the primary reason is that the sun’s heat fails to penetrate the home.

#1 Serious Insulation

You can insulate your home to ensure the minimum heat escapes outside.

Like a vacuum flask, the process that keeps your drinks hot can also keep your drinks cold.

If no heat can get out, no heat can get inside in the summer.

#2 Thick Stone Walls

Building a house with thick stone or concrete walls provides an insulating effect.

Like a cave, the stone walls keep the temperature inside the rooms relatively constant. You may notice a temperature drop in summer as you walk inside the house.

If you have a long hot summer, the heat may eventually build up in the walls, radiating the heat into the rooms – the same principle as a storage heater.

A stone step stays cool for a long time, but it stays hot for a long time when the sun succeeds in heating the stone.

#3 Permanent Shade

A house west of a mountain will remain in the permanent shade for most, if not all, day.

A house can have the cooling effect of shade from trees and other buildings, and the house remains cool because the sun’s heat doesn’t fall on the walls.

#4 Air Conditioning

It is evident that if you close your house and run the air conditioning, you create a colder interior.

Keeping your house significantly colder than the ambient air temperature all summer may cause some issues with mold and rot inside your home.

Local Cold Spots

Sometimes you get cold parts of your home in summer, whereas others respond to the rising outside temperature.

Why Is the Attic Cold in Summer?

It is unusual for an attic to be cold in summer.

Typically, the attic heats up because the sun on the roof provides passive solar heating combined with hot air rising. The loft usually is cold in winter because of heat escaping through the roof.

If the attic is cold in summer, it will likely be a combination of excellent insulation and shading.

Why Is the Basement Cold In Summer?

In summer, your basement acts like a cave.

An underground cellar has plenty of insulation; as cold air sinks, it is likely to be the coolest place in the house.

Even above ground, if your basement has few windows, it will likely remain appreciably cooler than the upper levels.

Why Is the Crawl Space Cold In Summer?

If the crawl space is open to the outside air, then an exchange of air will keep the crawl space at ambient temperature.

If you enclose the crawlspace, you turn it into a mini-basement and can end up with a cooler space beneath the house in a hot summer.

If you run air conditioning in the rooms above the crawlspace, cold air sinking helps keep this space cooler.

How Big Can the Temperature Difference Cost?

Artificially cooling your home can generate a twenty-degree temperature drop between hot summer weather and the interior.

Insulating your home means retaining heat inside and keeping external heat outside. You can expect an insulated home to maintain a steady temperature, but opening and closing doors and windows will move the air around.

How cool your home stays in relation to the outside depends on:

  • Temperature inside the house at the start of summer.
  • Temperature outside.
  • Shade.
  • Construction materials.
  • The number of air changes in a day.
  • Heating and cooling.

An insulated home may stay a steady 70F through the summer, but it will stay warmer for longer when it warms up.

How Can You Make Your House Warmer In Summer?

In a cold climate, you want to ensure you gain the maximum benefit from the free heat of summer.

Allowing the sun to warm up your home may need a few architectural or mechanical interventions:

Benefiting from Passive Solar Heat

The sun shining through windows will warm up a room.

Adding extra windows to the south side of your home (if you live in the Northern hemisphere) lets in the maximum heat. You may want to use glass with UV coating to lose the damaging parts of the sunlight but benefit from the heat.

An alternative to windows is to increase the capacity of a thermal mass to absorb heat during the day and radiate it back at night.

If you walk in a city after a hot sunny day, you can feel the concrete’s thermal mass releasing stored heat into the air. You can use the same principle for your home.

Your architect may recommend a dark cladding material or replacing a wooden wall with a stone wall.

Using Solar Energy

Converting sunlight into energy to provide free heat and light during the summer (and winter) months can make it more affordable to heat your home all year round.

In some areas, the summer heat is insufficient to heat your home from the outside.

You can use solar panels to generate electricity or direct solar energy to warm water through carefully positioned water pipes.

Install a Heat Pump

Different heat pumps use heat from the ground or the air to provide hot water and heating inside your home.

An architect specializing in green energy can advise you on the system that works in your location.

Heat pumps work down to 5F (-15C), so you gain benefits in cold climates, although they cease to be beneficial in extreme cold.

Heat pumps are an expensive solution but combine a heat pump with an underfloor heating system, and you can significantly affect your summer room temperatures.


If you want your home to warm up in the summer, you can help maximize the sunlight falling on your house and through your south-facing windows by removing large trees and adding hard landscaping like block paving around the house.

Trees provide shade and stop the sun from resting on your home. If you remove the shade, you gain additional heating from the solar rays falling directly on your home.

Hard concrete surfaces are slow to heat up but act as a storage heater overnight by radiating back the day’s stored heat.

Depending on your climate, you may gain additional warmth through appropriate landscaping.

Change Your Decor

If you can get sunlight into your home, you bring solar heat. Houses that are cool in summer tend to be dark.

You can increase the amount of light and warmth in your home by:

  • Using glazed exterior and interior doors rather than solid ones.
  • Use mirrors and reflective surfaces to bounce light into dark corners.
  • Add ceiling fans to push warm air towards the ground – similar to changing the ceiling fan direction in winter.

What About Winter?

How does making your home warmer in the summer impact your capacity to stay warm in winter in subzero temperatures?

Windows and Glazed Doors

During winter, most heat goes through the windows.

In summer, you want the heat to come through the glazing, but in winter, you want to stop the heat from flowing out.

You can minimize heat loss in winter by using:

  • Thermal one-way glass – more expensive than standard glass.
  • Heavy insulating drapes in winter months.
  • External shutters protect windows and doors.

Solar Panels and Heat Pumps

You can gain additional heating from these installations during the winter months to supplement the cost of heating fuel.

The solar panels require sunlight and will not work as efficiently in winter as in summer, but heating pumps work in low temperatures.

Landscaping Changes

Removing trees that provide shade also eliminates the risk of trees falling in winter storms.

But you lose the shielding effect of trees stopping storms from attacking your homes with unobstructed access.

A chat with an architect will help you plan your landscaping to ensure you get the best option for your climate.

It may be worth having less summer sun if you have shelter from high winds and driving snow in winter.

What If Your House Is Permanently Colder Than Outside?

If in winter weather your house is significantly colder than the outer air, then you face a combination of two factors:

  • Inadequate insulation radiates the expensive heat out of your home.
  • Inadequate heating.

The type of houses that are cool in summer take a long time to heat in winter. If you live in a cold house, you need to address insulation to a high standard to retain the heat you use in winter.

Next, you need to consider if your heating system can heat your whole house.

Your boiler may be underpowered, and you may not have enough radiators, or your heating system may need repairs.

Finally, you need to heat the home consistently to get it up to a comfortable temperature and retain the heat.

A solid stone-built home requires considerable heating to get it to the point where it feels warm, and then you can apply a smaller amount of daily heat to keep it at a level temperature.


The best temperature for your home is the one that means you can move comfortably without feeling too hot in summer or too cold in winter.

But different climates give different issues, and you may need to reduce your heating bills by maximizing the capture of summer heat for your home rather than trying to cool it down.

Remodeling the south side of your home may be more expensive than fitting solar panels or a heat pump, but you may combine this work with increasing your living space.

The best solution is the one that makes you happiest inside your budget, and an architect is one of the best people to give you a range of architectural and mechanical solutions to your cold house.