IsoDim Help Economy module

Purpose

This module is used for comparing the profitability of different insulation options. The annual energy loss and CO2-emissions can also be compared.

Calculation type

You have to select one out of six categories. In pipes the media is some kind of fluid/gas, in ducts it is always air.

Dimensions

Use the outside dimension of the pipe/duct (without insulation). The emissivity of the pipe/duct is used for calculating the uninsulated heat loss.

Orientation

When calculating the external heat transfer coefficient the orientation of the pipe/duct is needed.

Conditions

Description of the conditions around and inside the pipe/duct. Ambient (surrounding) and media temperature are used in all calculations. For outdoor conditions the wind speed also has to be given. For ducts the airflow is also necessary. Normally average (yearly) values should be used in this module (to give a correct calculation of the annual energy consumption).

Insulations

The different insulation options are added to this list. First you have to enter data for an insulation and then push 'Add insulation'. If you want to change the data for one option, select it in the list, alter the data and then press 'Update insulation'. To delete, simply select an option in the list and press 'Delete insulation'

Economical data

Six economical parameters are needed to perform the calculations:
  1. Energy cost pr kWh: the cost of heating the media, can be a mix of electricity, oil, gas or other. The efficiency of the heater should be included in the calculation of the price (example: The heater efficiency is 80 % and the price of energy supplied to the heater is 0,15 /kWh, the effective energy price is 0,15 / 0,8 = 0,1875)
  2. CO2-emission: Emission in grams pr kWh. The efficiency of the heater should also be included in this value (see energy cost).
  3. Energy inflation rate: An estimate on how much energy prices will increase during the depreciation time.
  4. Operating hours: If the system does not run the whole year this value should reflect this.
  5. Depreciation time: Can be purely economic (investment time-frame) or reflecting the lifespan of the installation
  6. Discount rate: Normally the interest rate used for investments, can be calculated based on general inflation and bank interest rates (both loans and deposits).
  7. Currency: Currency to be used for the calculations. Please note that the currency only changes the text in the calculated results not the numbers (there's no automatic conversion between currencies).

Insulation

In addition to choosing the insulation product, thickness and outside facing the total cost of insulating the pipe/duct should be entered. This cost should include extra labour costs for fitting the insulation.

Results

There are two tables showing the calculated results. The first line in both tables is always showing the results for the pipe/duct uninsulated. The highligthed option is the one with lowest total annual cost, this is not necessarily the option with the lowest heat loss or CO2-emission.