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What is SAP (Standard Assessment Procedure) And How Does It Work?


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SAP or the Standard Assessment Procedure is the UK government’s method for estimating the energy performance of new homes.  To build a house, it has to follow certain rules. Builders need a ‘pass’ on their SAP Calculations to meet these rules. If they don’t get a ‘pass,’ the building control won’t approve the house. That means it can’t be rented or sold. Moreover, this methodology is important for other reasons too. It helps the person designing the house to make it use less energy and cause less pollution.

The SAP rating shows how well the house uses energy. This information goes into the Energy Performance Certificate (EPC) that all buyers and renters see.

History of SAP

The Standard Assessment Procedure (SAP) has its roots in the Building Research Establishment (BRE). This was initially based on the BRE Domestic Energy Model (BREDEM). It was first published in 1993 and has undergone updates in 1998, 2001, 2005, 2009, 2012, and most recently in 2022. In 1994, SAP became the designated means of assessing the energy performance of dwellings, as cited in the Building Regulations.

By 2007, the government officially adopted it as the methodology for Energy Performance Certificates (EPCs). Moreover, its simplified and cost-effective version called Reduced Data SAP (RdSAP) was introduced in 2005.

This method streamlines the assessment of existing dwellings by relying on a set of assumptions. As a result, it reduces the amount of data that an energy assessor needs to collect.

How SAP works

The UK Government uses the Standard Assessment Procedure (SAP) to check how good houses are at using energy. Now there is Part L1A document of SAP. This is a set of energy rules for new houses. It was last updated in 2016).  These rules cover what new houses in England need to do to be good at saving energy. Moreover, it talks about things like how the building is made, how much heat it keeps, and other standards it has to meet.

Next, there is the Part L1B document, but it’s for existing houses. It talks about what to do when houses get fixed up or changed a lot, making sure they’re energy-efficient too.

Why do you need SAP?

Fundamentally, SAP serves two main purposes:

  1. Demonstrating compliance of new homes with building regulations.
  2. Generating Energy Performance Certificates (EPCs) for all homes. So it provides information to renters and potential buyers about a property’s energy health. So to get a ‘pass,’ the house has to meet targets for:
  • Keeping heat inside well
  • Using solar energy
  • Building quality and setting up systems correctly
  • Predicting how much pollution the house will make

Non-domestic buildings use a different method called the Simplified Building Energy Model (SBEM). In fact, SAP is a crucial tool in developing, implementing, and monitoring government policies. These policies are related to energy efficiency, fuel poverty, and heat decarbonization. The entire building industry widely employs it.

(SAP) Standard Assessment Procedure Calculations

Well, these calculations serve three main purposes:

Standard Assessment Procedure Calculator

Standard Assessment Procedure Rating

They calculate a SAP Rating, which indicates the energy-related running costs of a dwelling.

Compliance with Part L

Standard Assessment Procedure Calculations are used to demonstrate compliance with Part L of the building regulations. Further, they ensure that energy efficiency standards are met.

Energy Performance Certificate (EPC)

The utilization of SAP Calculations produces an Energy Performance Certificate (EPC). This certificate provides information on the energy performance of a property. Next, it is useful for occupants, potential buyers, landlords, and renters.

Furthermore, it’s important to note that slightly different rules apply if you need SAP for a conversion or extension.

Why Are SAP Calculations Important?

Standard Assessment Procedure Calculations are important for a few key reasons:

Meeting Rules

First, to finish a house or apartment, it needs to pass SAP Calculations. So if it doesn’t pass, the authorities won’t allow the property to be rented or sold.

Smart Design

Second, SAP Calculations help architects make homes that use less energy. Consequently, they figure out how different materials and heating systems affect energy use. This helps them create energy-efficient homes.

Sharing Information

The SAP rating tells people how well a home uses energy. The assessors use this rating to create an Energy Performance Certificate (EPC). So buyers and renters see EPC to understand the property’s energy efficiency.

Hitting Targets

Last but not least, to pass SAP Calculations, homes need to meet certain goals. These goals include how well the building holds heat. Plus whether it uses solar energy, and the quality of construction. Consequently, meeting these goals makes the home more energy-friendly.

What is involved in SAP Calculations?

Plans and Details

A SAP Assessor uses architect plans, construction details, and a full HVAC (heating, ventilation, and air conditioning) specification. Drawings must be accurate and scaled. They need to show all necessary details like elevations, sections, floor plans, and site plans.

Creating a Model

The assessor uses these plans to create a model of the dwelling(s) in Standard Assessment Procedure software. This involves scaling off the plans either electronically or by hand.

Adding Systems

The model adds heating, lighting, and ventilation systems. It selects specific products from manufacturer databases.

Thermal Elements

The model adds detailed information about thermal elements such as walls, floors, roofs, and openings. Moreover, calculations for thermal junctions are also part of it. Next, renewable technologies and cooling systems also find their place.

Detailed Reports

Once they include everything, the SAP calculation produces detailed reports. These reports cover various aspects such as site form, heat losses, energy demand, and seasonal variations. They also contain CO2 emissions and contributions from renewable technologies.

Difference between SAP and EPC?


SAP helps calculate how well a building uses energy. This leads to an Energy Performance Certificate (EPC). Moreover, only new houses or places changed into houses, as old schools turned into apartments, need these calculations. Next, there is no need to visit the place for SAP. They use drawings and information about how engineers make the building. The building then gets a rating from A to G, where A is super good at saving energy, and G is not so good. Old homes usually get a D rating, but new ones usually get a better rating, like a B or even an A.

What’s more, only new homes or old buildings turned into homes need a remote SAP assessment. On the other hand, a Domestic Energy Assessor needs to visit existing homes in person for EPC calculations before selling or renting a household.

On top of that, older buildings use a simpler assessment called RDSAP to create an EPC. So if an old home is difficult to figure out, RDSAP uses standard values to help the assessor. In short, SAP is for new or renovated homes, done remotely. RDSAP is for older homes. It needs a visit to create an EPC.

How to get SAP assessment?

As mentioned earlier, assessors typically conduct the SAP assessment remotely, so they will need important drawings and information from you.

These include

  • Floor plans and cross-sections made by an architect.
  • Pictures or plans showing the building from different sides or a map of the site.
  • Details about how the walls, floors, ceilings, and roof are built.
  • Information about all the windows in the house.
  • Specs for any renewable technologies in use.
  • Details about the heating system in your home.

What’s the average Standard Assessment Procedure Calculation?

The SAP score ranges from 1 to 100, dividing into categories from A to G. Homes that score from 92 to 100 get an A rating, meaning they are super good at saving energy. SAP Rating helps compare how well different homes use energy, and the score ranges from 1 to 100+. A higher SAP rating means lower fuel costs and less carbon dioxide emissions. If the score is over 100, it even suggests the home is making more energy than it uses.

Future of Standard Assessment Procedure

The future of SAP involves the development of a new methodology called the Home Energy Model. This is driven by recommendations from the Climate Change Committee (CCC) and a scoping study commissioned by the former Department for Business, Energy and Industrial Strategy. The aim is to enhance accuracy, and robustness, and ensure it aligns with net-zero goals.

In December 2023, the industry published a consultation on this new methodology. They also sought input to aid in the ongoing development process. This consultation on the Home Energy Model is open until 6 March 2024.

The developers are still working on the Home Energy Model. They plan to implement the first version alongside the Future Homes Standard in 2025. This signifies a commitment to advancing energy performance assessment methodologies in line with evolving energy and environmental standards.

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