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SAP Appendix Q

SAP Appendix Q

The Standard Assessment Procedure (SAP) represents the governments chosen methodology for calculating the energy efficiency and carbon dioxide emissions of residential buildings and new homes. The calculation is used to ensure the property complies with Building Regulations 2000 (Part L - Conservation of fuel and power) for England and Wales and provide energy performance ratings (EPR) for Energy Performance Certificates (EPC). It is the only calculation methodology available for new homes.

Within the Code for Sustainable Homes (CSH) SAP is used to calculate Dwelling Emission Rate (DER) and Target Emission Rate (TER) which influence the overall sustainability rating of the home.

Changes to building regulations Part L (Conservation of fuel and power) have been made inline with the Governments pledge to reduce carbon dioxide emissions and make all new housing carbon zero by 2016. These changes are driving homes to become more energy efficient, along with the mandatory introduction of the Code for Sustainable Homes (CSH), which specifies minimum energy efficiency levels. In order to meet new energy efficiency levels new homes have become more air tight as a means of reducing heat loss and energy usage. To comply with Part F (Means of ventilation) ventilation must be maintained within the home to ensure a healthy environment and limit the build up of condensation.

In a move to comply with both Part L and Part F of the building regulations a number of new technologies have been introduced into the market to enable heating and ventilation needs to be met.

SAP, the current method used to assess energy use and carbon dioxide emissions, was developed to use standard input data for ventilation and energy conservation requirements. However, since the introduction of SAP, a range of new and improved existing technologies with higher energy efficiency have been developed. As a result SAP Appendix Q has been developed to enable the performance data from these new technologies to be integrated into the existing SAP assessment calculation for energy efficiency evaluation. The SAP Appendix Q website holds a searchable data base of all approved technologies that can be entered into SAP under appendix Q.

A new or improved technology can qualify for inclusion within Appendix Q following independent testing and approval by BRE Technology. Categories currently listed within appendix Q include:

  • Mechanical Ventilation Systems

Mechanical Extract Ventilation (MEV):

This is a fan driven ventilation system that extracts air from the dwelling and incorporates both centralised (air is extracted from wet rooms via ducting and expelled by means of a central fan) and decentralised (air is extracted by continuously-running fans in each wet room) systems.

Balanced Whole House Mechanical Ventilation:

These are systems that provide fresh air to habitable rooms and extract air from wet rooms which are balanced systems without heat recovery (extract air from wet rooms using ducting and expel through a central fan, whilst supplying air to habitable rooms via ducting and a central fan or by individual supply air fans within each room)

Mechanical Ventilation with Heat Recovery (MVHR):

A heat exchanger is incorporated within the ducting of the outgoing and incoming air supplies.

Flue Gas Heat Recovery Systems (FGHRS)

A system that enables the heat contained within flue gases to be recovered. It can be passive or may be powered with a pump.

Waste Water Heat Recovery Systems (WWHRS)

Systems that enable heat to be recovered from grey water that is being disposed of. Recovered heat is transferred to the mains water and either fed directly into the consuming appliance or a hot water generation system.

Hot Water Only Boilers

A boiler dedicated to the supply of hot water only. Any space heating may be provided by part of the same system or a separate system.

Mechanical ventilation systems are tested for energy consumption (measured in watts per litre of air moved) and the energy efficiency of heat exchangers measured within heat recovery systems are tested by measuring heat returned to incoming air.