Attic - Walls - Floors - Basement - Crawl Space - Insulation
Jun082016

What Causes a Hot House in the Summer?

Published by Admin at 9:33 AM under Blog

Every summer we get a lot of calls from people who are having comfort issues in their home, usually on the second floor. Many homeowners find that even with the air conditioner blasting, only the lower level of the home will get cool, leaving the second story so hot that it’s uninhabitable

Homeowners tend to blame the AC unit for the hot house issues, but we find that it’s often a problem with the house itself. 

 

Hot house issues can be caused by a variety of things, such as:

 

·       Poor Thermal Boundary (Insulation and air seal)

·       Not enough supply air coming through the force air registers. 

·       Poor attic ventilation (roof vents)

·       Dark roof color

 

Let's break it down a bit:

 

The Thermal Boundary is the shell of the house. The “shell” or “envelope” consists of the Attic, Walls, Basement, Floors and Crawl Space. More than 90% of the attic spaces in US homes are under insulated and poorly sealed. This is exacerbated during the summer months because your attic space can easily reach over 140 degrees for most of the day. You need plenty of the right kind of insulation and an airtight seal to combat these kinds of extreme temperatures.

 Next we have possible issues with the air supply. The actual AC may be functioning well, but it could be fighting an uphill battle, so to speak. Most air handlers (Furnace/AC fan) are in the basement and therefore have to push air all the way up to the second floor. In order to reach the second story, the air has to pass through multiple turns (elbows) and travel a long distance, causing a decrease in air pressure (CFM). The air that ends up coming out of the second story vents generally comes out with substantially diminished air pressure. If you toss in issues with your Thermal Boundary, your HVAC system has very little hope in keeping your home cool, no matter how much you blast the AC.

In summer we get a lot of calls from people who are having comfort issues upstairs. They have a 1 1/2 or 2 story home and can't keep the upstairs areas cool. We see many cases where the second floor is uninhabitable much of the time. 

 

Things to consider:

Thermal boundary - If the "shell" of your home isn't properly air sealed, even the best air conditioners couldn't keep your home cool. Consider hiring a professional to do a blower door test to see if your home is leaking conditioned air. 

 

HVAC- Is your HVAC system up to date? Have you had your Air Conditioner cleaned recently? Something as simple as cleaning out the vents can make a huge difference in the temperature in your home. 

Attic ventilation is a huge problem for many homes. It is essential to have plenty of the right kind of roof vents to properly cool the attic space. Remember, that space can top 140 degrees in the hot summer months.  Ideally, the attic would have 1 square foot of ventilation for every 300 square feet of attic space, split 50/50 between the top and bottom of the area. Most homes don’t meet this standard.

If you believe your attic is one of the many that don’t meet the standards, give us a call. If it’s not possible to retrofit your current roof vents, we can use mechanical vents that are either hard wired into your house power, or better yet, solar-powered.

 

Roof color might not seem like it could have a huge impact, but consider this – on a hot summer day, would you rather stand in the sun in a black T-shirt or something with a lighter shade? Your roof functions in the same way. The shade/color of your roof can make a big difference in the temperature of the attic space, darker colors can soak up heat and trap it in your home. It might not be cost-effective to completely redo your roof, but it’s something to keep in mind for when you do any updates in the future.

 

 

All summer long, we get calls from people who are sweating in their homes and paying way too much on their energy bills. We have an excellent track record for finding successful solutions for each individual home. Give us a call and let us help!

314-884-0092