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Reducing DER Carbon Dioxide Emission Levels

In order to maximize the opportunity for compliance using electric heating, there are 8 key considerations building designers should take, noting that in all probability more than one of these improvements will be needed to achieve compliance.

Example Building

This example takes a 'worst case scenario', with building fabric standards to 2002 elemental u-values and with electric storage / panel heating specified:

• Typical block of 6 flats. Average floor area = 52.5m2
• Built to 2002 standards: U values: wall – 0.35, windows – 2.0, ground floor – 0.25, roof – 0.16
• Air permeability = 10m3/m2/hr@50Pa
• Openings = 25% of floor area

TER = 36.76 kgCO2/m2/yr
DER = 45.76 kgCO2/m2/yr

Because the DER is greater than the TER target, unsurprisingly this 'worst case' scenario building fails to comply with the new Part L requirements. Click on the links below to see how modifying various building specifications can allow compliance to be achieved.

• Basic Fabric Improvements
• Improve the Controllability of the Heating System
• Reduce the Glazed Area
• Consider Supplementary Renewables
• Heat Common Areas
• Consider Mechanical Ventilation With Heat Recovery
• Reduce Air Permeability
• Reduce the Hot Water Cylinder Capacity

Combinations of Measures to Achieve Compliance

While, based on the 'worst case' scenario above, none of the measures alone provide a direct route to compliance, various measures can be combined very effectively to achieve a positive compliance result, for example:

1. Improved u-values + improved heating system efficiency + reduced openings + solar water heating (top floor flats only)

-	Original Building	Improvement Level	Kg CO2 saving
U-values	2002 elemental values	Intermediate package	4.26
Openings % floor area	25%	17%	0.69
Common areas heated	No	No	-
HW cylinder capacity	170L	170L	-
Air permeability	10	10	-
Heating system	Storage heaters + panels	DuoHeat + panels	2.25
Renewables	None	2m2 solar (top floor flats only)	2.01
-	-	-	-
Block TER	Original Block DER	Improved Block DER	Total
36.76	45.76	36.55 PASS	9.21

2. Improved u-values + improved heating system efficiency + reduced openings + heated common areas + reduced air permeability

-	Original Building	Improvement Level	Kg CO2 saving
U-values	2002 elemental values	Basic package	2.74
Openings % floor area	25%	17%	0.69
Common areas heated	No	Yes	4.27*
HW cylinder capacity	170L	170L	-
Air permeability	10	7	1.47
Heating system	Storage heaters + panels	Panel only	3.32
Renewables	None	None	-
-	-	-	-
Block TER	Original Block DER	Improved Block DER	Total
34.57	45.76	33.27 PASS	12.49

* making this change also reduces the TER slightly to 34.57