Air Conditioning Makes Basement Too Cold? Here’s What to Do!


The overall comfort of individuals who are staying in the house can be improved with the help of an air conditioner. But when trying to air condition a living space that consists of multiple floors, a number of issues can arise.

For example, in the summer, two-story houses are known to often have their basements freezing when the rest of the house is hot. Although many strategies exist to fix this common problem, it’s often questionable what to do when air conditioning makes the basement too cold.


When the basement is too cold while the rest of the house feels too warm, it’s necessary to employ certain methods to balance the indoor temperature across all floors. These can be natural air ventilation, sealing cracks, adding supply and return ducting, replacing leaky windows, and using mechanical systems such as fans, furnaces, or dehumidifiers.


Below are included some great methods that are going to help balance the temperature in your house. So make sure to read them carefully as they can also help you save money on heating and cooling bills!


Why Are Basements Colder than the Rest of the House?

During the winter months, going downstairs to the basement (or what’s worse if you sleep in a basement bedroom) can prove exceptionally cold. The majority of basements, even if the basements are finished, are naturally colder than other areas at home.

Generally speaking, basements are always damper than other upper levels due to poor ventilation, and water often seeping directly through concrete or rising out of a dirt floor.

High moisture levels will result in far colder conditions than the ambient air temperature and consequently, you are going to feel much colder. This is due to the fact that high humidity conducts more heat away from the body than dry air.

Trying to reduce moisture in the basement through sealing cracks or increasing ventilation is always recommended as the first resort. But the simplest method is to utilize a dehumidifier, an effective and often affordable device that is designed to eliminate excess water from the air.

Given that cold air weighs more than hot air, the laws of physics come into play and cause temperature differences. The cold air, as it settles, will start to rise displacing the hot air. Since the basement is the lowest part of any building, it will inevitably remain the coolest.

What’s more, this is true even if you have sufficient insulation and added furnishings in the space because the source of the problem is entirely unrelated to the cold outside air seeping inside.

Even in winter, direct sunlight that passes through the windows is able to raise the temperature inside the house by as much as 10 degrees. However, basements don’t receive any sunlight coming in, even having small window openings. This results in the basement failing to benefit from the sun’s heat.

Additionally, the higher air temperature on the upper floors is going to prevent the thermostat from triggering the heater that is supposed to run. Although it lowers your power bills, it leads to the basement becoming excessively cold.



What Is the Temperature Difference Between Upstairs and Downstairs?

In a standard two story house, there is a noticeable 8 to 10 degree difference in temperature between the downstairs and upstairs. This is due to the fact that, by default, the heat will travel from lower to higher levels as it evaporates. This causes higher floors to become warmer than the lower ones.


How to Get Cold Air from the Basement to the Upstairs?

There are a number of approaches for you to consider to get cold air from the basement upstairs.

When you add both return and supply ducting in your basement, this will allow for the movement of air to the upper floors without creating any dangerous imbalances in pressure. However, doing so increases the total use of energy as the basement would now have to be constantly heated during the colder months. Accordingly, the implementation of ducts should only be performed by a professional heating contractor who will able to properly measure the flow of air across return, supply, vents or chimney.

Another way to make your current duct system more efficient is to tighten up the existing ducts. Home duct systems differ in tightness between the supply and return sides where the supply side is tight and the return side is very leaky. That air leakage results in warmer indoor temperatures on the upper floors of the house while leaving the basement cold.

Thus, seal all the joints, seams, and perforations in the return ducting, in a forceful way. You should use metallic duct tape or a mastic duct sealant that is painted on seams and joints.

In the event that your basement is finished with no direct access to the ducting, your only option would be to let a heating contractor seal all of the ducts from the furnace area.

As the older home furnace fans models use quite a lot of electricity, running the fan continuously can be very expensive. Intermittent operation of the furnace fan proves to be a better solution. Besides switching your furnace fan on and off, an easy fix is to use a portable box fan to push cold air upwards. For this, you may put the fan at the top of the basement stairs, which will help get rid of some freezing air.

Newer models of furnaces that have variable-speed fan motors might save up to 80 percent of electricity and might be the best option for continuous fan operation.


The basement is the space in the building where moisture imbalances produce all sorts of indoor air pollutants, unpleasant odors, or mold growth. A lack of ventilation results in an increased likelihood of odors released from toxic chemicals and household products like paint, automobile parts, solvents, and other cleaning products. Moreover, the unventilated space fails to sufficiently migrate the cold air, blocking it from moving up to the higher floors that suffer from a temperature imbalance.

There are two fundamental methods for basement ventilation, i.e. natural and mechanical.

Natural ventilation is known to be used with the help of naturally existing currents in the open air. Yet, this form of ventilation only works for basements that have strategically placed windows that can be opened and closed easily.

While this technique is thought to conserve energy, it requires significantly more resources to set up and maintain.

It’s suggested that windows are located on opposing sides from each other across the area in order to follow the basement’s natural drafts. As previously pointed out, damp and unventilated basements can be helped with the use of a dehumidifier.

However, continuous excess levels of moisture and dampness will most likely require the alternative method of mechanical ventilation to get the best results.

When applying the mechanical ventilation method, vents and fans are utilized to exhaust stagnant air in the basement by delivering fresh air from the outside. This can oftentimes be as simple as installing small window level fans on opposite sides of a room, or as complex as the installation of a fan that uses a pipe for ventilation.

A large number of homeowners lean towards this strategy given the superior automation and flexibility. In addition, mechanical ventilation is required for houses that test positive for certain chemicals including and especially that of radon, a leading cause of lung cancer among non-smokers in the United States.

Basic mechanical ventilation systems start with a design plan and depend much on the basement’s size and appliances and furnishings located in the area

For basements that are small to medium-sized, it’s preferred to use an exhaust fan on one side of the area with a ventilation fan on the other.

Such fans can be installed within existing cavities of windows permanently, or may require custom-built openings that are cut through the parts of the basement wall that’s above ground.

The mechanical ventilation systems that are best come with humidity sensors for the ease of automation. When a certain level of moisture is detected by the sensor, the fans will start to run and vent the air until the moisture level is brought down. According to the Environmental Protection Agency (EPA), it’s recommended for homeowners to maintain a basement environment below a humidity level of 60 percent to inhibit the persistent mildew and mold growth.



How to Balance Heat in a Multi Level House?

To explain it in the simplest way, air balancing is defined as the process of measuring and adjusting an air conditioning system to deliver the desired amount of air and provide a comfortable temperature in every part of your house.

The balancing process consists of a number of integrated tests that determine the efficiency and correct functioning of a heating, ventilation and air conditioning system (HVAC).

It frequently happens that an HVAC system is 30 to 50 percent low on airflow. It is important to have it checked by a certified technician as the effectiveness of the air conditioning unit is fully dependent on the amount of airflow.

The technician can diagnose, and then repair and balance the duct system for maximum performance. This way, all the rooms and areas in your home will maintain the same temperature throughout, you’ll be able to better control humidity and have cleaner air, with increased energy savings.

As you might be aware of, multi level homes, due to their inherent design, present significant challenges for balancing cold and warm air, especially in the summer and winter months.

It’s recommended to close any air registers at the lowest level of the house over the summer and any registers at the higher level of the house over the winter. This will result in air being forced from the furnace or air conditioning unit into areas of the house that it would not be able to typically reach.

Thus, the closure of registers during the winter will force warm air to move downstairs, and at the same time, maintaining a cozy temperature on the higher floors.

Enabling the thermostat fan setting will force a constant circulation of air inside the house despite the air conditioning or furnace not running. This indoor air circulation will balance the overall temperature in your home.

Besides placing fans directly in your basement, as mentioned before, it’s suggested to put table fans in various places around the house. This will also assist in the consistent movement of air. For instance, any fan that is placed near the bottom of the stairs pointing upwards will help to push the cool air to the upper floors.

Finally, if temperature differences continue to be problematic, insulation of the windows and attic could be a good solution. It’s vital that the air that is cooled down or heated up doesn’t escape from the house. Any windows that are old or leaky need to be urgently replaced. This is even more important during the colder months of the year when drafts are preventing the basement temperature from rising.

Also, it’s known for the basement temperature to be even colder than upstairs during winter. So, if you’re planning to leave your house for a longer period, set your thermostat to balance the temperature so as to prevent your pipes from freezing.


To Sum Up,

Being the lowest level of a house, basements have naturally cooler environments than their upper floor counterparts.

When you have a multi level house, you certainly need to implement various techniques and systems to balance the indoor temperature across all floors. These include but are not limited to natural air ventilation, and the use of mechanical ventilation systems.