544
edits
Changes
m
* Column A gives a series of BTU values derived from the buyenergyefficient.org web site <ref>http://buyenergyefficient.org/</ref>. *Column B is based on an expert rule of thumb of 14 BTU per cubic foot, plus an extra 1000 BTU for good measure. *Column C uses the spreadsheet calculator.
* Number of occupants * Area of each accommodation * Area of windows and degree of sun exposure * Energy efficiency of windows * Shading of windows * Degree of insulation in the boat * Heat gain through the engine room bulkhead * Heat gain from AC machinery in the accommodation * Heat gain from DC machinery in the accommodationHeat gain from DC lights in the accommodation
→Method
= Air Conditioning Calculation =
== Summary == Calculating air conditioning is more complex than heating. Air conditioning can be supplied through forced air or a water-based chiller. Three methods of calculation are illustrated, including a provided spreadsheet.
== Method ==
Calculating air conditioning is more complex than heating and so the answers are more varied. The below table gives three sets of estimates to illustrate the issue.
Except for the last two data points, methods A and C are in good agreement, but make your own judgement.
The spreadsheet calculator is adapted from Air Conditioning Your Home <ref>http://www.nrcan.gc.ca/energy/publications/efficiency/residential/air-conditioning/6051</ref>, published by the Energy Office of Natural Resources Canada (NRCAN) and available from its web site. It appears to fall within the general range of the other methods, based on area alone. Most rules of thumb are designed for single rooms, or two rooms joined. The author's calculator considers numerous more factors:
Several approximations were made in adapting the NRCAN model. For example, houses have a fixed position, allowing us to calibrate the different heat gain from windows facing any compass quadrant. Boats are mobile, allowing windows to face any direction at any time. The calculator assumes the worse case, with one full side of the boat having maximum southern sun exposure, the other minimum, i.e., it is moored east-to-west.