SAP Explained

The Standard Assessment Procedure (SAP) is the UK Government’s official method for assessing and comparing the energy efficiency and environmental performance of dwellings. Developed by the Building Research Establishment (BRE) in 1992, SAP provides a consistent, accurate, and reliable assessment of a dwellings energy performance.

SAP and Building Regulations

Since 1994, Part L of the Building Regulations has used SAP to evaluate the energy performance of buildings.

Waste Water Heat Recovery (WWHR) in SAP

SAP assesses the energy consumption of a dwelling while maintaining a set level of comfort and service. By using standard assumptions about occupancy and behaviour, it allows like-for like comparisons between different dwellings.

Factors such as fuel costs and CO2 emissions are determined from the assessment. SAP quantifies a dwelling’s performance in terms of energy use per unit of floor area, a fuel-cost-based energy efficiency rating (SAP Rating), and CO2 emissions (Environmental Impact Rating).

WWHRS is listed in the Products Characteristics Database (PCDB), which contains information on various technologies used within different National Calculation Methodologies (NCMs), including SAP and rdSAP(Reduced Data SAP). WWHRS targets energy use associated with hot water, particularly from showers, offering one of the highest cost vs SAP impact ratios.

The efficiency of WWHRS in SAP depends on several factors, including:

• Number of occupants calculated by SAP for the dwelling
• Total number of rooms for showering/bathing
• Number of rooms with WWHRS installed
• Whether the room has only a shower or a bath and shower
• The System (A/B/C) installation method used

By improving shower hot water efficiency, Waste Water Heat Recovery Systems helps lower energy consumption, reduce costs, and enhance overall SAP performance.