Why is the Upstairs Too Hot?

So why is the upstairs so hot? We are looking at issues specific to upstairs. We deal with the general issues of too hot too cold portions of the house here  and deal with specific mechanical issues here-LINK but here we are concentrating on those attribute which can make an upstairs too hot.

Upstairs can be extra warm just because warm air floats. But there are other things going on too.

Upstairs can be extra warm just because warm air floats. But there are other things going on too.

When upstairs are really intolerable, we have to clarify whether the upstairs has been remodeled and you have a bonus room reclaimed from the attic or from over the garage. Remodelers are pretty notorious for making things pretty and not paying as much attention to construction details. You miss some details like air barriers here or securing new insulation properly and you can create the conditions for extreme temperature torture. We talk about what can happen and what to do about a temperature issues with a bonus room- a remodel here.

We bad mouth builders and remodelers here. LINK

But their are unique issues with being upstairs that create issues with too hot.

Lets talk about the effects of the stack effect first.

The stack affect is basically warmer less dense air floating on cooler air. In winter, the hottest air in the house will be floating up and you are likely cozy upstairs unless you are getting cold radiation from a cold wall or window or a poly wall as part of a remodeling. Heat does not rise. Hot air expands and is more buoyant than cold air- so warm air rises. This is critical because all that buoyant warm air in your house is working to get upstairs.

The stack effect makes your home even more susceptible to air infiltration. Buoyant warm air is looking to get higher and find cracks and gaps in attics and the usual suspects for leakage, we address air leakage issues here. This is a critical subject to cover because warm air leaking into to cold spaces creates high humidity and moisture problems. All homes leak air. Some homes leak a lot. Older homes leak more than modern green homes.  Air leaks make a major impact on your comfort and on your energy bill. Vertical homes with upstairs, the impact of the stack affect makes the impact of leaks even more critical to comfort. We discuss air leak problems and solutions here. LINK.

[textbox – cold upstairs… ever? Incidentally if you have issues with too cold upstairs in winter, you really have an air leakage problem and you are paying out way too much for energy. The propensity for hot air to float up should keep you mostly comfortable in the heating season. [textbox]

Another special effect from being upstairs is that space is smaller and you end up closer to walls or windows. We cover solar gain and thermal bridging in the upper level doc on too hot to cold. Here, in the upstairs, dimensions are closer and therefore more impacted by radiating surfaces. See notes on radiating bodies here. 


Differential temperatures between upstairs and down can manifest in various ways.

If people live downstairs and the person controlling the thermostat spends time upstairs in the heating season- well there could be a bit of a family feud because in in the cooling season, you might be chilly downstairs to keep the upstairs comfortable. And being chilly in conditioned air is a waste of funds. Cooling is expensive, and the results are not linear. i.e. more cooling becomes much more expensive. LINK

In the heating season, the downstairs can be cold as the upstairs is warm and toasty. This becomes a zoning issue and we discuss these kinds of issues here… but remember, solving problems with air laeks and insulation, is the key area to start making the home comfortable. Make sure you see the article on too hot too cold areas around the house for a descripton of the forces which might be making you uncomfortable. Any special treatments for a hot upstairs must have a foundation of building science.

Where do we go for solutions to such an issue?

As you read this article, did you get a sense of where you might have an issue? You have what I would figure are two choices here unless you have a trusted construction advisor, and would you be in this spot, if you had that?

You need to get more familiar with the role of the home energy auditor. They can provide clear and unambiguous data to your situation using a variety of testing equipment. Their thermal camera- in the process called thermography can take some images of your heat flow problems and make some suggestions for you.

Or maybe you know a great HVAC service company that is moving beyond the traditional role of installing cooling boxes and transforming into a home  performance company. What do I mean by that? Traditionally, HVAC companies have solved moisture problems with dehumidifiers, and dry air with humidifiers, and too hot with bigger pieces of HVAC equipment. This does not work.

Building science has brought real answers to the table and the new age of HVAC servcie companeis understand this. You need to make sure you are hearing about air leaks and insulation and not have the answer start off about the HVAC unit…

The role of the future HVAC company dealing with home performance issues and your home energy rater will get closer. We need to understand building science before we can make smart choices in design, in retrofit and in installation of new equipment.

We have a great discussion of the process of finding the professional you are most comfortable to deal with serious comfort issues here. You can get the size of help you feel you need, but it needs to fit within the realm of building science for your home.


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