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What Is Conditioned Space?

Wednesday, November 6th, 2013 by Brian Stewart

St. Louis Dr. Energy Saver is your trusted HVAC contractor When it comes to home energy efficiency, conditioned space is defined to be space in your home for which you provide heating in winter and cooling in summer.  This seems like a simple definition but often becomes confusing in practice.  Defining what you consider to be the conditioned space of your home can help guide you in making decisions about comfort and energy efficiency.

What to consider when conditioning your home

Here is one way to help your understanding of what constitutes conditioned space.  Consider a house with a finished basement.  Let’s say the basement has finished walls, floors and ceilings.  Is that basement a part of the conditioned space of the home?

The answer is, we don’t have enough information about the house.  We do not know whether the basement has ductwork, a heat source, or a source of cooling.  We don’t know anything about whether the space is heated or cooled.  A finished basement and a conditioned basement are two different things.  We do not know whether this basement is conditioned space or not.

Conditioning your home through the seasons

In the St. Louis area, our climate is heating dominated.  This means we spend more money heating our homes in winter than we spend cooling them in summer.  That said, we do have four seasons in our area.  We need to keep the conditioned spaces in our homes comfortable and energy efficient not only in winter, but in summer as well.

Unfinished basements in the St. Louis area are often part of the conditioned space of the house.  Even with exposed concrete floor and walls, ductwork in the basement is often used to heat the space in winter and cool the space in summer.  Another easy example of conditioned space is an attic that has been converted to living space and supplied with heating and cooling.

An example that can be harder to identify is a crawl space under a house with leaky ductwork.  In the crawlspace example, even though the ducts are really intended to carry heating and cooling to the house above, the ducts often leak “conditioned” air into the crawlspace.  Although this leakage is unintentional, such crawlspaces are often kept warm in winter.  They are referred to as unintentionally conditioned space.  This situation can be thought of as a waste of energy.  It can also be thought of as a great way to keep the floors above the crawlspace warm and comfortable in winter.

Conditioning your home while making it energy efficient 

Defining the conditioned space of your home is a choice.  You can decide to heat and cool any portion of your home you want.  Once you make that decision, you can then make further smart decisions relating to comfort and energy efficiency.  For example, should you air seal and insulate the underside of the floor over a crawlspace or would it be better to tackle the ground and the foundation walls?  Should you air seal and insulate the floor of your attic or the underside of your roof?

To answer the questions above, start by defining your conditioned space.  This definition will help you make smart choices about how to make your home more comfortable and energy efficient. Contact us today to schedule a free home insulation estimate.

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About the author
Brian Stewart is the General Manager of Dr. Energy Saver St. Louis. He has many years of experience making homes more comfortable and energy efficient.

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