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At Base Energy we can help design and assess your development to meet SAP / SBEM Part L 2013 compliance and we can help guide your development providing various cost effective solutions.

The new Part L 2013 is stricter than ever and harder to comply. You can’t just install solar PV panels and pass your SAP calculation. The fabric elements play a key part in the design and assessment of new buildings and if designed correctly will pass the building energy calculation. If you do not design it correctly from the outset, you will find it difficult to pass the SAP calculation at the end.

It is likely your project will need to exceed the minimum u-values* set out by Part L 2013, with their being a Fabric Compliance target. This is alongside the CO2 emission target, and the fabric compliance takes into account, u-values, air tightness, thermal bridging and thermal mass.

A SAP calculation is required for building regulations, Part L1a and Part L1b (existing). It is a heat loss calculation; working out the fuel cost of the dwelling and the CO2 emissions.

See below for an idea of the type of specifications needed to pass a Part L 2013 SAP calculation, based on some of our most common house types:

Standard Semi Detached House, 40sqm (Improved Fabric/Low Air Tightness Option)

 

Elements Improvement How to Achieve Compliance
Thermal Mass Low Thermal Mass Timber or Lightweight block
External Wall Meet U-value of 0.24 W/m2k 100mm Crown Dritherm 32
Ground Floor Meet U-value of 0.16 W/m2k 100mm Insulation Board
Roof Meet U-value of 0.11 W/m2k 400mm Mineral Wool
Windows Meet U-value of 1.3 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 4 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Thermal Bridging Lintels Lintel Psi Value (0.05) Keystone Hi Lintels
Heating Controls Install Improved Heating Controls Timer and Temperature Zone, Weather Comp

 

Standard Semi Detached House, 40sqm (Renewables Option)

 

Elements Improvement How to Achieve Compliance
Thermal Mass Medium Thermal Mass Medium to Dense block
External Wall Meet U-value of 0.26 W/m2k 100mm Crown Dritherm 32
Ground Floor Meet U-value of 0.18 W/m2k 85mm Insulation Board
Roof Meet U-value of 0.13 W/m2k 350mm Mineral Wool
Windows Meet U-value of 1.4 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 5 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Heating Controls Install Improved Heating Controls Timer and Temperature Zone Control
Renewables/Extra Features Photovoltaic Panels Approx. 0.5 kWp, South Facing

 

Standard Semi Detached House, 40sqm (Mechanical Ventilation Option)

 

Elements Improvement How to Achieve Compliance
Thermal Mass Low Thermal Mass Timber or Lightweight block
External Wall Meet U-value of 0.24 W/m2k 100mm Crown Dritherm 32
Ground Floor Meet U-value of 0.16 W/m2k 100mm Insulation Board
Roof Meet U-value of 0.11 W/m2k 400mm Mineral Wool
Windows Meet U-value of 1.3 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 5 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Heating Controls Install Improved Heating Controls Timer and Temperature Zone Control
Renewables/Extra Features Efficient Ventilation System Mechanical Ventilation Heat Recovery

 

 

 

Large Detached House, 150sqm (Improved Fabric/Lower Air Tightness Option)

 

Elements Improvement How to Achieve
External Wall Meet U-value of 0.18 W/m2k 150mm Crown Dritherm 32
Ground Floor Meet U-value of 0.12 W/m2k 125mm Insulation Board
Roof Meet U-value of 0.1 W/m2k 450mm Mineral Wool
Windows Meet U-value of 1.4 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 7 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidlines
Heating Controls Install Improved Heating Controls Timer and Temperature Zone Control
Renewables/Extra Features N/A N/A

 

Large Detached House, 150sqm (Standard Option)

 

Elements Improvement How to Achieve
External Wall Meet U-value of 0.21 W/m2k 75mm Insulation Board
Ground Floor Meet U-value of 0.16W/m2k 100mm Insulation Board
Roof Meet U-value of 0.1 W/m2k 450mm Mineral Wool
Windows Meet U-value of 1.3 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 5 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Thermal Bridging Lintels Lintel Psi Value (0.05) Keystone Hi Lintels
Heating Controls Install Improved Heating Controls Time and Temperature Zone, Weather comp
Renewables/Extra Features N/A N/A

 

 

Large Detached House, 150sqm (Renewables Option)

 

Elements Improvement How to Achieve Compliance
External Wall Meet U-value of 0.21 W/m2k 75mm Insulation Board
Ground Floor Meet U-value of 0.17 W/m2k 85mm Insulation Board
Roof Meet U-value of 0.11 W/m2k 400mm Mineral Wool
Windows Meet U-value of 1.4 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 6 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Heating Controls Install Improved Heating Controls Timer and Temperature Zone Control
Renewables/Extra Features Photovoltaic Panels Approx. 1 kWp, South Facing

 

Large Detached House, 150sqm (Mechanical Ventilation Option)

 

Elements Improvement How to Achieve Compliance
External Wall Meet U-value of 0.21 W/m2k 75mm Insulation Board
Ground Floor Meet U-value of 0.17 W/m2k 85mm Insulation Board
Roof Meet U-value of 0.11 W/m2k 400mm Mineral Wool
Windows Meet U-value of 1.4 W/m2k Double Glazed, Argon Filled
Air Tightness ATT of 4 m2/hm3 (@50Pa) Seal Junctions Correctly
Thermal Bridging Achieve Standard y-value (0.08) Follow ACD Guidelines
Heating Controls Install Improved Heating Controls Timer and Temperature Zone Control
Renewables/Extra Features Efficient Ventilation System Mechanical Ventilation Heat Recovery

 

It is more difficult for larger houses to comply with the SAP assessment, and therefore require improved u-values and other energy efficient systems. The air tightness of larger houses is also more difficult to achieving low air test results.

There are many new products and materials available now which can be included in the SAP calculation. Such as improved heating controls, shower heat recovery, insulated lintels, thermal mass can actually have a big impact, with reduced heat demand and therefore makes it easier to comply.

Contact us to speak to one of our assessors to help you comply with Part L or check out our SAP Checklist Guide

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