This calculator will provide an estimate of the heat loss for your home.
It estimates the following:
Please note these important sources of error.
Fill in all the input boxes. They look like this -->
(medium blue backgrounds)
When you have filled in all the inputs, click the "Calculate" button. It looks like this ------>
When you click "Calculate", the output cells will be calculated and displayed. Note that any time you change an input, you must hit "Calculate" again to update the results. There are links to help files in the form to explain the inputs, and provide some help in figuring out what to enter for your situation.
There are a couple of worked examples here.
Help on R values... If you are starting with no insulation, read this carefully...
Handling crawl spaces ...
Help on Heating Degree Day estimates...
Definitions of the Output Columns:
Design Heat Loss -- This is the total heat loss from your house per hour when the outside temperature is at the Design Outdoor Temperature that you input. This can be used as a rough guide for sizing your furnace -- but see the discussion on Internal Gains above. (BTU/hour)
Year Heat Loss -- This is a rough estimate of the total heat loss from your house for a typical year. It is based on the number of Heating Degree Days you entered. For the reasons discussed here, it may be somewhat more than what you actually experience. (BTU/year)
Fuel Cost -- This is the cost of the fuel to heat your house based on the Year Heat Loss from the previous column, and the fuel type, fuel cost, and furnace efficiency you entered. For the reasons discussed here, it may be somewhat more than what you actually experience. (Dollars)
Ten Year Cost -- This is the cost of fuel for 10 years with the assumption that fuel costs will rise 10% each year of the 10 years. For the reasons discussed here, it may be somewhat more than what you actually experience. (Dollars)
Greenhouse Gas Emissions -- This is the yearly green house gas emissions from your heat plant. It is based on the type of fuel you selected, the furnace efficiency you entered, the Year Heat Loss. For electricity, it is assumed that the electricity was generated at a coal fired power plant -- about 50% and increasing of electricity in the US is produced in coal fired power plants. For the reasons discussed here, it may be somewhat more than what you actually experience. (lbs of CO2 per year)
I take no responsibility whatever for the accuracy or correctness of this software.
I take no responsibility whatever for any grief that errors, omissions, or just plain bad design in this software may cause you.
You use this software at your own risk.
Gary 5/5/07, 3/2/08, 12/18/2008
Updated: April 17, 2008 Clarified slab effective R value, added two examples.
Nov 7, 2009 Added some more help files
April 4, 2011 Fixed some formating and nav menu issues