First, attic temperatures that put Death Valley to shame, in the 140-150-160-degree range, add lots more “heat load” to your system through your ceiling area, making it harder to cool your home. For most homes, this ceiling area is one of the largest factors in your home comfort, as well as equipment size.
There's no doubt attic ventilation can impact the effectiveness of the air conditioning system. Removing the built-up heat inside the attic that radiates from the sun baking the roof is essential. Otherwise, that heat can transfer into the living space which increases the burden on the AC system.
The ideal attic temperature should be no less than 60 degrees in the winter and no more than 10 to 20 degrees above the outdoor temperature in the summer. If your attic temperature climbs above 130 degrees, you may start running into issues with your energy bill, as well as the integrity of your roof.
Note excessive heat – if it's 90 degrees outside, the attic temperature shouldn't be more than 110 degrees. More often than not, attic temperatures will be in excess of 125 degrees on a 90 degree day. This will overwork your air conditioning equipment, run up your utility bill and shorten the life of your roof.
Increased Cooling Load: A sweltering attic becomes a heat reservoir, transferring heat into your living spaces below. As a result, your air conditioning system works harder to maintain a comfortable indoor temperature, leading to higher energy consumption and increased utility bills.
On a 100-degree day, an attic can reach temperatures of 170 degrees or more due to the radiant heat effect.
By improving ventilation in your home's attic, installing an attic fan can help reduce moisture and even lower the temperature within your entire house.
If it's 90 degrees outside, most people would set their AC to a perfectly comfortable temperature of 68-72°F.
So, how hot should your attic be? Ideally, the attic temperature should be close to the outside temperature, give or take 10 to 20 degrees. If your attic temperature is getting to 130 degrees or hotter, you can expect to see damage to your home.
Add a few fans
Fans are an easy and affordable way to reduce heat in your attic, as they help to create a draft and make the room feel cooler. Switching on a few electric fans for an hour or two a day helps the air circulate through the room, eventually pushing the hot air out.
Install electric ventilators and attic fans, which remove hot air from an attic. They have thermostats that turn the fan on at a recommended preset temperature of 100-110 degrees. Alternatively, install passive vents such as gable, soffit and ridge vents, which are openings in the roof that allow hot air to escape.
Working in an attic with an internal temperature of 100°F+ will inevitably result in increased perspiration and a huge loss of body fluid.
When it comes to an attic fan's temperature setting, it's best to adjust it to anywhere from 90 to 110 degrees Fahrenheit. It's impossible to state a single number because your attic can effortlessly soar above 95 degrees (on average).
The short answer, yes, insulating the attic is an effective way to keep your home cooler during the summer months. While it's a given that the insulation in your attic will keep the home warmer during the winter, it isn't immediately obvious that insulation can also help to keep the home comfortable during the summer.
During scorching temperatures, your AC works harder to remove heat from your home, putting a strain on the system. This can lead to: Reduced efficiency: The hotter it is outside, the less efficient your AC becomes.
If you had to choose just one—and your attic has a great need for ventilation—an attic fan is your best bet. Attic fans in the $300 to $400 range can move upwards of 5,000 CFM. For lower capacity ventilation at a steep cost savings, a ridge vent might be your best choice.
If your attic temperature is consistently hitting 130 degrees or hotter, damage to your home and a high utility bill is very likely. You can keep a thermometer in your attic to check – it doesn't have to be an expensive one and will give you a better idea of how hot things really are.
Thanks to the radiant heat affect, attic temperatures on a 100-degree day can reach 170 degrees or more.
Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces. Use the JM insulation calculator to determine the recommended R-value for your project, as well as how much insulation you'll need.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.
Just because the outdoor temperature is above 100, the Ideal temperature to set your AC unit to doesn't change — it's 78 degrees. Higher temperatures in the home are to be expected when the weather is hotter than usual, but your thermostat can still be set the same as if it were a lower temperature outside.
On average, this process takes roughly two and a half to three and a half hours. However, this is not a one-size-fits-all answer. The cooling duration can be swayed by various elements, such as the efficiency of your HVAC system, the home's insulation quality, and even external factors like direct sun exposure.
Why are attic fans not used anymore? Due to inefficiencies in relying on existing attic vents for air intake, attic fans have lost popularity. These vents often aren't designed for this purpose, resulting in inadequate replacement air supply.
The primary function of attic fans is to promote airflow within the attic, which can help reduce temperature and moisture levels and provide several valuable benefits.
You don't need to have your attic fun running all of the time. Having it running only when it's needed maximizes its benefits for your home's AC and overall energy efficiency.