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Salus Technical Update – Part L2A 2013 here.
The 2013 version of Part L2A (conservation of fuel and power in new buildings other than dwellings) has now been released and comes into force from 6th April 2014.
The headline change is a 9% reduction in the carbon dioxide emissions from the mix of new buildings, which although not as big an improvement as was expected, it is still to be welcomed and comes into effect (in England only) on 6th April 2014.
Aggregate Approach – Percentage reduction on 2010 for notional building package
| Aggregate Reduction |
Resultant Target Reduction |
| Warehouse (distribution) |
5.6% |
| Office (Deep-plan, AC) |
11.9% |
| Warehouse (Retail) |
6.8% |
| Office (Shallow-plan, AC) |
12.2% |
| Hotel (5-star) |
8.8% |
| Secondary School |
8.3% |
| Note: PV not a requirement on the notional building | |
Yet again the limiting U-values for the main fabric of the building remain unchanged as detailed in Table 1 below.
Table 1 – Limiting fabric parameters
| Fabric element |
2010 U-values (W/m2K) |
2013 U-values (W/m2K) |
| Roof |
0.25 |
0.25 |
| Wall |
0.35 |
0.35 |
| Floor |
0.25 |
0.25 |
| Windows, roof lights and glazed doors |
2.20 |
2.20 |
One major change from Part L2A 2010 is that a wider set of “notional buildings“ has been defined, the air permeability and thermal requirements are detailed in Table 2 below.
Table 2 – Resultant Notional Building Specification – ADL 2A 2013 for a 9% reduction
|
U-values (W/m2K) |
|||||
| Element |
Side lit or unlit (Heating only) |
Side lit or unlit (Includes cooling) |
Toplit |
||
| Roof U-value (W/m2.K) |
0.18 |
0.18 |
0.18 |
||
| Wall U-value (W/m2.K) |
0.26 |
0.26 |
0.26 |
||
| Floor U-value (W/m2.K) |
0.22 |
0.22 |
0.22 |
||
| Windows U-value (W/m2.K) |
1.6 (10% FF) |
1.6 (10% FF) |
N/A |
||
| G-Value (%) |
40% |
40% |
N/A |
||
| Light Transmittance (%) |
71% |
71% |
N/A |
||
| Roof light U-value (W/m2.K) |
N/A |
N/A |
1.8 (15% FF) |
||
| G-Value (%) |
N/A |
N/A |
55% |
||
| Light Transmittance (%) |
N/A |
N/A |
60% |
||
| Air permeability (m3/m2/hour) | Varies between 3 and 7 dependent on the gross internal floor area of the building – where the floor area is less than 250m2 or over 10000m2Note: GIA = Gross Internal Area | ||||
| GIA ≤ 250m2 |
5 |
5 |
7 |
||
| 250m2 < GIA ≤ 3,500m2 |
3 |
3 |
7 |
||
| 3500m2 < GIA ≤ 10,000m2 |
3 |
3 |
5 |
||
| 10,000m2 < GIA |
3 |
3 |
3 |
||
| Element |
Side lit or unlit (Heating only) |
Side lit or unlit (Includes cooling) |
Toplit |
||
| Light Luminaire (lm/circuit watt) |
60 |
60 |
60 |
||
| Occupancy control (Yes/No) |
Yes |
Yes |
Yes |
||
| Daylight control (Yes/No) |
Yes |
Yes |
Yes |
||
| Maintenance Factor |
0.8 |
0.8 |
0.8 |
||
| Constant illuminance control |
No |
No |
No |
||
| Heating efficiency |
91% |
91% |
91% |
||
| Central SFP (W/I/s) |
1.8 |
1.8 |
1.8 |
||
| Terminal Unit SFP (W/I/s) |
0.3 |
0.3 |
0.3 |
||
| Cooling (SEER/SSEER) |
N/A |
4.5 / 3.6 |
4.5 / 3.6 |
||
| Cooling (mixed mode) (SSEER) |
N/A |
2.7 |
2.7 |
||
| Heat recovery efficiency (%) |
70% |
70% |
70% |
||
| Variable speed control |
Yes |
Yes |
Yes |
||
| Demand control ventilation |
Yes |
Yes |
Yes |
||
As can be seen from Table 2, compliance with the new Part L2A maintains the emphasis on having a well insulated building fabric which cannot be achieved by adopting the limiting fabric parameters identified in Table 1.
Lighting
2010
- Actual design lux level irrelevant – rebased to notional building value.
- So supermarket designed to 2000 lux, rebased to notional building 800 lux.
2013
- Actual installed lighting wattage used so penalising overlit spaces.
- Maintenance factors are assumed in the notional and should be included in calculated values in the actual
- Constant luminance controls are available in the actual
- LENI method can be used to show compliance with Criterion 2
District Heating
2010
- Notional CO2 emission factor for heat supplied from district heating same as in actual.
- Little carbon benefit from connection to district heating.
2013
- Minimum CO2 emission factor applied to notional building.
- Allows carbon benefit where efficient district heating is employed.
- Removal of Accredited Construction Details (ACDs)
- No quality assured accredited construction details schemes have been approved by the Secretary of State.
- The confidence factor of 0.02 W/mK or 25 per cent is no longer applied.