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SIPs & SAP Calculations

You will need a SAP calculation for residential buildings at Design Stage and when the construction is complete.


Making changes during the build can impact the final calculation, and with ever-stricter emission targets to cope with, getting the specification right on your development is more important now than ever.


What is a SAP?

A SAP (Standard Assessment Procedure) is required for new build domestic buildings. It is a calculation for modelling your design and checking compliance with CO2 targets.

The SAP model is created using design drawings and it is checked against building regulations (Approved Document Part L in England and Wales, and Technical Handbook Section 6 in Scotland).


To show compliance on new builds, the Dwelling Emission Rate must be equal to or lower than the target.

A SAP may also be required for existing residential buildings that are being extended or renovated.

Structural Insulated Panels play an important part when it comes to complying with the increasingly stringent Part L of the Building Regulations and the SAP 2010.


The SAP rating is a measure of the overall energy efficiency of a dwelling and considers many factors, not just the building materials, these include the efficiency of the heating system, the u-values of all the building elements and any renewable technologies that might be being used.


Several of these areas are met and enhanced by using the Eco SIPs Homes Building System.  

Some of the benefits of using Structural Insulated Panels for SAPs are listed below:

Excellent U-values.  By specifying the Eco SIPs Homes Building System, you will achieve low u values, as low as 0.13 on the walls and 0.10 on the roof, helping you to heat your property more efficiently. Look at our product data sheet at the technical section for more on U values.


High levels of air-tightness.  Due to the inherently air-tight way that Eco SIPs Homes are constructed, structural insulated panel builds typically have lower air pressure results, meaning easier SAPs. A typical Eco SIPs Homes house kit will achieve between 2 and 4 acph @ 50pa and can achieve even lower if panel joints are taped. We highly recommend taping all vertical panel joints, horizontal joints at sole plate and head binder, and around window and doors to ensure you get the best levels of air-tightness possible. 


Less cold-bridging.  With timber frame there is a repeating cold bridge caused by the timber studs at 600mm centres and at 1200mm centres with a closed SIP panel system. Our open panel system uses SIPs splines to connect panels together reducing the cold bridging. For more information on the SIP joining spline look at the product data sheet or standard construction detail in out technical section.  There is therefore minimal cold bridging in the walls, making for better SAP results and easier compliance with Part L.

Lower thermal mass.  Contrary to popular belief, SAP 2010 generally looks on lower thermal mass more favourably than higher thermal mass.  Thermal mass is the ability of a substance to absorb and store heat. The higher the thermal mass, the slower it responds to changes in atmospheric temperature.  SAP 2010 takes the view that if something responds quicker to heat changes, the user can turn off the heating / cooling quicker and therefore use less energy.  Structural insulated panel structures have lower thermal mass than some other forms of construction.


These points were re-iterated by Jon Ponting of Energist UK who are SAP rating and EPC specialists.


Jon said:    

"Structural insulated panels can perform favourably in the latest SAP Calculations to show compliance with Part L, provided they are installed and used correctly.

They can help to provide very low air test results, they have low thermal mass and can also benefit from low levels of thermal bridging. The higher specification SIPs panels are fitted with additional levels of insulation, so lower U-Values can also be taken as a benefit when building to the new Part L.

Air flow and ventilation rates are a key element to showing compliance with the latest SAP methodology, so any material or device which can help a developer do well with the above four points should be strongly considered for future developments."

You can Contact us to find out how using SIPs can help you make SAPs easier.



Click on the image below for a link to the Energist UK website

Construction Phase Plan CDM 2015
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