Wood Pellet v Oil

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Cormac Regan
Posts: 30

Wood Pellet v Oil

Postby Cormac Regan » Fri May 17, 2013 1:33 pm

Hi -
I recently worked on a project were we used wood pellets and we TER of 10.3 and a BER 9.9.

The client did not have enough money to go down the pellet route and we changed to an oil fired system TER of 29 and a BER 26.4 (using same efficiencies etc)

This would suggest that using an oil fired system, it is easier to get a pass.
Anyone one know why?

Is it because we are trying to make a 25% reduction compared to 2006, and while pellets are LZC, the technology hasn't improved that much since 2006, trying to get an extra 25% is difficult.

This compares to oil efficiencies improving slightly, making getting a pass a bit easier.

Andrew Bairstow
Site Admin
Posts: 504
Location: Birmingham, UK

Postby Andrew Bairstow » Mon May 20, 2013 10:57 am

the reasons are down to how the 2010 Notional Building is defined and how that is different to the 2006 Notional Building.
In the 2006 Regs then when the building had a biomass heating system the notional building was modelled with a natural gas heating system. The current emission rates (probably the same or very similar to those used in 2006) are 0.013kgCo2/kWh for biomass and 0.198kgCo2/kWh for gas, thus any building with a significant heating load could get through the building regs with minimum efficiencies for the other services.
The 2010 Notional Building heating system (in simple terms) uses the same fuel as the actual building. This means that:
1. When biomass is the heating fuel then the CO2 contribution of the heating system will be small, the boiler efficiency will be relatively insignificant and the BER will be dominated by the other services: The focus for passing building regs will depend on efficient design of the lighting and other systems.
2. When oil is the heating fuel then a highly efficient boiler will have a greater impact on the BER and may be one of the key specifications to achieve a building regs pass.
in the example building below with the same energy demands for 'Heating' and 'Cooling/Aux/Lighting/Hot Water' combined. If the building is heated by biomass then heating will represent a mere 2% of the BER (and a similar proportion in the Notional Building). If the building is heated by oil (same efficiency system) then heating will represent 35% of the BER (and a similar proportion in the Notional Building).

Heating All Others
kWh 50 50
Case 1: Biomass as Heating Fuel, All other services Grid Electricity
emissions factor 0.013 0.517
Actual CO2 0.65 25.85
%CO2 2 98
Case 1: Oil as Heating Fuel, All other services Grid Electricity
emissions factor 0.274 0.517
Actual CO2 13.70 25.85
%CO2 35 65
Andrew Bairstow
DesignBuilder Software

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