SAP CALCULATIONS
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ENERGY PERFORMANCE CERTIFICATES (EPCs)

If you require a SAP Calculations then our team can assist you with this important documentation to support either a planning or building control request to determine that all is in order with the new extension you are proposing. Lately, customers are asking for excessive glazing within the extension design, for example, Bi-folding doors, Sky lanterns, Skylights and windows. Having excessive glazing reduces the U-value of the house so justification needs to be demonstrated in the means of a Calculation report (SAP) and Energy Performance Certificates (EPCs)

Here at DPL we can deliver SAP Calcs and EPCs at any short notice at an affordable price.

DO NOT PURCHASE OR ORDER ANY WINDOWS OR DOORS WITHOUT IT

SAP CALCULATIONS ARE NEEDED PRIOR TO BUILD

Most homeowners are unaware that choosing Bi-Folding Doors and Windows when designing their extension needs any form of checking, they assume because chosen by themselves and shown on the drawings they can build from the chosen design of their choice, but this is not the case. To comply with Part L of the Building Regulations building control inspectors will ask for SAP calculations to justify the U-Values of the Extension. Windows and Doors lose a lot of heat, so preparing SAP calculations will identify if the type of Windows and doors are acceptable.

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What are SAP Calculations? and Why are they needed?

SAP stands for "Standard assessment Procedure". It is a government-approved system put in place to assess the energy rating of the new Extension to the home or a Loft Conversion. A final SAP rating is given with a figure between 1 - 100+ to compare the energy performance of the Extension. 100 represents a zero energy cost, anything over means exporting energy. Basically the higher the SAP number the better for the homeowner meaning lower fuel costs with fewer bills to pay. The lower the SAP number would mean higher bill costs as the home would be not as good as keeping the heat in. There are various elements that conclude the final SAP findings, they are:

 

1. THE HOMES HEATING SYSTEM

2. THE HOMES INTERNAL LIGHTING

3. RENEWABLE TECHNOLOGIES INSTALLED

4. THE CONSTRUCTION OF THE EXTENSION (insulation)

5. THE HOMES HEATING SYSTEM

SAP CALCULATIONS ARE USUALLY NEEDED WHEN ADDING
THE TOTAL PROPOSED AREA OF EXTERNAL WINDOWS AND DOORS WHICH EXCEEDS 25% OF THE FLOOR AREA OF THE PROPOSED EXTENSION. 

"THE AREA OF THE PREVIOUS EXTERNAL OPENINGS INTO THE HOUSE THAT WILL NO LONGER EXIST CAN BE ADDED TO THE ALLOWANCE."

"HOW TO CALCULATE THE GLAZING AREA OF MY EXTENSION?"

The existing external Window and Door opening areas need to be added up to find out if the proposed openings exceed 25% of the Extension floor area, the example below is to help understand the works easily.

EXISTING AREAS 

The existing kitchen window (only 3 years old double glazed) will be reused and thus this cancels out the new kitchen window. Also, we have (photo attached): a single door 2m x 0.8m (single glazed) a double door 2m x 1.3m (single glazed) an existing window 1.15m x 1.15m (double glazed) The total Existing area of openings - is 8sqm2.

NEW GLAZING AREAS

Skylight 1 - 2.7sqm2, Skylight 2 - 2.7sqm2,

Skylight 3 - 2.7sqm2, Window 2.5sqm2

(reusing double glazed timber)
Bi-Folding Doors 11.2sqm2.

The total area of new glazing - is 21.8sqm2

Minus the area of the existing of 8sqm2 = 13.8 sqm2    

 

The area of my extension is 34.6sqm2. 

13.8 ÷ 34.6 = 0.39884393063584 = 39.884393063584%

"As that is still 39%, well over the 25% rule I guess I will still need a SAP Calculation from an assessor to Justify the proposed Windows and Doors I would like to purchase and install on my property."

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ADVICE FROM THE SAP ASSESSOR................

JOHN STOBBS - SAP SERVICE UK

"UPDATE Calcs and New regs Calculations (New Regs) are very difficult to get to work with SAP as other factors are now required to be worked on Whole house SAP for an extension, which is sometimes impracticable and means more work for the designer...

no one has the software issued yet and the average weighted method is very strict with glazing and UValues so one should expect them to be more tricky and re-design may be required.


We have done a few where the glazing has to be 0.80 ? Wall Uvalue at 0.10 ?
 

The Government has made it so strict that we see more issues attached now.
 

We at present cannot get easy passes anymore and client need to be aware that starting work before calcs are done is very very dangerous.

Warm Regards

John Stobbs"

On the 15th of JUNE 2022, PART L Volume 1 and Part F volume 1 of the Building Regulation approved documents have been amended, it is now essential that all drawings get examined and issued with a plan check certificate prior to building and purchase of materials. 
 

We can supply you with a SAP calculation service carried out by an audited assessor, for that peace of mind knowingly confident that you are purchasing the right windows and doors for your project to comply with Building Regulations.

SAP Calculations Reports from - £150+VAT

DO NOT PURCHASE ANY DOORS OR WONDOWS WITHOUT IT!

Consumer Awareness before Purchasing Windows & Doors 

We have had several clients order Bi-folding Doors or large Skylanterns from overseas because of the cheaper products available well before drawings are approved at Planning Stage to find that when submitted to BuildingControl because the amount of total glazing exceeds 25% a SAP calculation request is demanded by the Building Control inspectors for justification of a pass. The SAP assessor then calculates the input on a model with all materials specifications which are going to be used finding out the Windows and Bi-Folding doors fail! leaving the homeowner with a very expensive loss. We advise getting a SAP assessor to evaluate your extension design to demonstrate the products which are going to be used well before the construction stage or purchase of materials.

CONTACT US FOR YOUR SAP CALCULATION REPORT

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Thanks! Message sent, John will get back to you shortly.