New Welsh Part L 2014 – Non-Domestic Buildings changes

Welsh building regulations

The second of three blogs on the new Welsh Part L 2014 Building Regulations. This one is about the changes affecting non-domestic new build.

The new Welsh Part L Approved Documents will be implemented from 31st July 2014. For non-domestic there is a 20% aggregate improvement over 2010 levels to be introduced.

The notional building recipe has been retained and for some areas tightened. This is the overall recipe for compliance for the notional building, however actual performance of some elements may need improving if any of the other elements are relaxed.

Element

Side lit or unlit (Heating only)

Side lit or unlit (includes cooling)

Toplit

Roof U-value W/m2K

0.18

0.18

0.18

Wall U-value W/m2K

0.26

0.26

0.26

Floor U-value W/m2K

0.22

0.22

0.22

Window U-value W/m2K

1.6 (10% FF)

1.8% (10% FF)

N/A

G-value (%)

40%

40%

N/A

Light transmittance (%)

71%

71%

N/A

Roof light U-value W/m2K

N/A

N/A

1.8 (15% FF)

G-value

N/A

N/A

52%

Light transmittance

N/A

N/A

57%

Target Air-permeability (m3/m2/hour), note: GIA = Gross Internal Area
GIA ≤ 250m²

5

5

7

250m² < GIA ≤ 3,500m²

3

5

7

3,500m² < GIA ≤ 10,000m²

3

5

5

10,000m² < GIA

3

5

3

 

Element

Side lit or unlit (heating only)

Side lit or unlit (includes cooling)

Toplit

Lighting Efficacy (lm / circuit watt)

65

65

65

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/l/s)

1.8

1.8

1.8

Terminal Unit SFP (W/l/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

Area of PV, % floor area

5.3%

5.3%

5.3%

On top of this, a new target metric has been introduced, the Primary Energy Consumption. The Welsh Government expressed a desire to implement an Energy Efficiency test, before the application of renewables. There is therefore now alongside the TER, a Target Primary Energy Consumption (TPEC) and an associated Building Primary Energy Consumption (BPEC) alongside the BER.

 This has been introduced to try and avoid ‘green wash’ i.e. specifying inappropriate measures which help with compliance, but which could lead to increased building energy use and carbon emissions.

Primary energy means energy that has not been subjected to any conversion or transformation process. For a building, it is the delivered energy plus the energy used to produce the energy delivered to the building. It is calculated from the delivered energy using primary energy (conversion) factors. The TPEC and BPEC calculation is primarily a measure of the energy efficiency of fabric and the building services. With a primary energy target it is not possible to incorporate renewable technologies to compensate for lower performing fabric and services standards, both the TPEC and the TER need to be met, so the fabric needs to be properly considered alongside the carbon emissions target.

Other Blogs on this topic:

New Welsh Part L 2014 – Domestic buildings
New Welsh Part L 2014 – Retrofit, material changes of use and extensions

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About

Jon Ducker is a qualified energy assessor working for Kingspan Insulation Ltd. He has an extensive knowledge of energy efficiency, renewable energy systems and sustainability in buildings with an expert knowledge of the relevant sections of buildings regulations and standards and their interactions with SAP. He provides authoritative advice regarding energy assessments for a wide range of public and private sector clients.

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