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TEACHER’S NOTES BIOMASS HEATING PROJECT 06 LOCAL / DISTRICT HEATING / ONTARIO, CANADA• The total heating energy demand was calculated by adding the space heating and domestic hot water (DHW) heating energy for all buildings. The domestic hot water heating base load is then expressed as a fraction of this total.• The heating energy demand for each building cluster was calculated by adding the space heating and DHW heating energy, as provided in the data table. The heating load for each cluster (in W/m2) was then set to yield the correct heating energy demand. The Microsoft Excel “Goal Seek” function may also be used to find the right input (e.g. heating load) when the output (e.g. heating energy demand) is known.• The formula method was used to calculate the heating network costs and a cost factor of 0.5 was applied to both the main and secondary distribution lines to reflect the favourable conditions for burying pipe.• Parasitic electricity was calculated using the method described in the Online User Manual: the biomass boiler is estimated to have a power draw of 14.2 kW while the power for the circulation pumps is calculated as: 1,337 m x 1,747 kW x (58.7 x 10-6)ºC/m ÷ 40ºC = 3.5 kW. This calculation is based on the total of the main (707 m) and secondary (630 m) distribution piping. Adding the boiler and circulation pump loads and multiplying by 2,993 h, the equivalent full load duration hours, gives the parasitic load of 53,000 kWh/yr.• Note that in the Financial Analysis worksheet, the RETScreen model calculates the avoided cost of heating energy ($47/MWh) by dividing the total cost of fuel for the base case system ($245,701/yr) by the total heating energy demand (5,230 MWh). This value is also the cost of the energy that the district heating system’s owner charges to its client.• This analysis is done from the perspective of the municipality, which is proposing to install and operate the district heating system. The five buildings that are to be heated will continue to pay the equivalent rates for energy as they were paying for the old natural gas heating, but these payments will now be an income stream to the municipality. For the building owners, financial benefits of the new system will include protection from price volatility of natural gas and elimination of the capital and maintenance costs associated with operating their old heating systems.
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