zero carbon and sap

SAPs in Detail and Getting to Zero Carbon

Preparing for Zero Carbon Seminar February 2011

Claire Westron Rund Partnership Ltd

• Code for Sustainable Homes• Planning Policy requirements• Building Regulations Part L• SAP • Case studies

Local Authority Planning Policy

Southampton – Code Level 4 and 20%

Eastleigh – Code Level 4 and 15% energy from renewable sources

New Forest – Code Level 3 (4 from April 2012)

Bournemouth – Code 3 (from Summer 2012)

Winchester – “Policy Aspiration” Code Level 5 (Energy and Water sections only)

What is the future for Part L?Reduction in Carbon emissions overPart L 2006

Reduction in Carbon emissions overPart L 2010

Revisions to Part L

Code Level 3 25% - 2010

Code Level 4 44% 25% 2013

Code Level 5 100 100% 2016

Zero carbon

2016 zero carbon new homes policy includes only the emissions covered by Building Regulations (heating, fixed lighting, hot water and building services)

Emissions from cooking or from plug-in appliances will not be addressed as part of this policy.

Zero Carbon Hubwww.zerocarbonhub.org

Part L Consultation

What are the main factors affecting the SAP assessment?

Dwelling size, type and orientation

U-values

Thermal mass

Thermal bridging

Air Pressure Test

Ventilation

Heating, hot water and controls

New technologies

Thermal Bridging

Where two heat loss elements meet, there is the potential for heat to be lost via increased conduction

• Repeating e.g. timber studs dealt with in the U value calculation • Non repeating

3 possible specifications:

•Default y = 0.15

•All details conform to Accredited Construction DetailsSAP 2005 - default y = 0.08SAP 2009 - y value to be calculated by assessor

3. Details conform to another Government Approved Source

Air Pressure Test

• Test all dwellings

• example – 3 bed semi

Air pressure test

TER DER % improv

4 18.52 18.26 + 1.4%

6 18.52 19.35 - 4.5%

Ventilation

Key points

• SAP 2009 rewards MVHR less than SAP2005, making it easier to

achieve compliance with natural ventilation

• There is a huge variation in efficiencies of MVHR systems

• Where air tightness is better than 5, additional background

ventilation is needed

• Where as built air tightness is better than 3 the ventilation

strategy needs to be checked

Heating and Hot Water

• Gas / oil / biomass boilers

• Heat pumps

• Solar thermal panels

•Secondary heating e.g. wood burning stoves

New technologies

•Shower Heat Recovery Unit

•Photovoltaics

•Flue Gas Heat Recovery

•Wind turbines

•Hydro power

Case studies

1. 2 bedroom flat

2. 3 bedroom semi detached house

3. 4 bedroom detached house

Part L Code 4 Code 5 (2016)

U valuesWallsRoofFloorWindows

0.190.11n/a1.4

As Part L As Part L

Ventilation MVHR MVHR MVHR (improved efficiency)

Air pressure test 5 5 3.5

Thermal bridging Accredited Construction Details

Accredited Construction Details

Accredited Construction Details

Heating and hot water

Gas combi boiler Air Source Heat Pump

Communal biomass boiler to block

Renewable None None 0.7kWp PV

Type : 2 bed flat (57m2)

Shower Heat Recovery Unit

Improved hot water cylinder insulation

Enhanced Construction Details

3

MVHR (improved efficiency)

0.200.110.151.3

Code 4Part L Code 4 Code 5 (2016)

U valuesWallsRoofFloorWindows

0.220.120.151.4

As Part L 0.200.110.151.3

Ventilation MVHR MVHR MVHR (improved efficiency)

Air pressure test

4 4 3

Thermal bridging

Accredited Construction Details

Accredited Construction Details

Enhanced Construction Details

Heating and hot water

Gas system boiler Gas system boiler

Improved hot water cylinder insulation

Renewable None 1kWp PV 3kWp PV system

Type : 3 bed semi (85m2)

Part L Code 4 Code 5 (2016)

U valuesWallsRoofFloorWindows

0.240.170.171.4

As Part L As Part L

Ventilation Natural Natural Natural

Air pressure test 7 7 7

Thermal bridging Accredited Construction Details

Accredited Construction Details

Accredited Construction Details

Heating and hot water

Gas system boiler Gas system boiler Biomass boiler (wood pellets)

Renewable None 1.2kWp PV 1.6kWp PV

Type : 4 bed detached (125m2)

Future changes to SAP• Thermal bridging - 19 more junctions to

consider• Degree of pipe insulation• Changes to carbon emission factors• Revisions to solar radiations (changing outputs

from PV and solar thermal)• Lower default efficiencies for heat pumps

Claire Westron

Code for Sustainable Homes and SAP Assessor

email: clairew@rund.co.uk tel: 023 8062 3750