Now that we understand the three types of heat loss or transfer, lets take a high level look at the major categories of heat loss in a home according to the numerous studies that have been referenced in the websites below.
While the studies vary slightly, and your actual home heat loss may vary based on many factors (including home age, original insulation levels and materials, degradation of seals throughout the home, and measures you have taken to improve heat loss since you have taken ownership), the general consensus is represented in the graph below.
As you can see, the largest source of heat loss is through conduction of heat through floors, ceilings and walls. While in total this is significant, it is spread out over a great deal of area, and does require in some cases significant investment to address. The balance of the heat loss includes a variety of other categories, primarily consisting of convection heat loss, or the loss of heat through air leaks and drafts.
As you can see in the thermal image of a typical home heat loss below, the most concentrated loss of heat exists around doors, windows, chimney, vents, and baseboards.
Here is an important point to consider when setting your economical strategy for reducing home heat loss: Reduction in convection heat loss, particularly air leaks, is often much less expensive per Gigajoules saved than addressing the conductive heat loss through walls, floors and ceilings. This is because readily available do-it-yourself products for sealing windows, vents, flues, electrical outlets, and door gaps can be found at your typical hardware store for very cost effective prices.
Consider the cost/benefit of weather stripping and installing door draft blockers for 3 exterior doors: $80 per 11% heat loss reduction, or just $7.27 per percent energy savings. Now consider the potential cost of addressing the floors, ceilings and walls with improved insulation, conservatively: $800+ per 31% heat loss reduction, or at least $25.80+ per percent energy savings. This last figure will vary greatly depending on the age of your home and the amount of improvement you are willing to pay for.
The key point is that many of us would most likely choose to attack the low hanging fruit first, to get the proverbial "most bang for our buck". So in the posts to follow, we will look more closely at these simple and economical, yet effective do-it-yourself solutions.
For more information, and articles used as references for the images and data used above, please see the following sites:
www.greenghent.wordpress.com/2008/03/06/energy-issues-step-one/2008/03/06/energy-issues-step-one/
www.energysavers.gov/tips/home_energy.cfm
www.eere.energy.gov/consumer/tips/pdfs/energy_savers.pdf
