A Path to Success


As SAP calculations have been required under Part L of the Building Regulations since 1995, most developers will be familiar with them. However, they can be daunting for first-time self-builders and developers. What’s more, because of the extreme tightening of CO2 emissions targets, driven by UK and European climate policies, SAP tests are much, much harder to pass than they used to be. Your average new build from 5 or 6 years ago is unlikely to pass today’s regulations. 

So, in order to ensure you pass your test and don’t have any hiccups in the process, let’s get stuck into the ways you can be in a better position to avoid them.

Building Plans

Building plans are a must-have, not a nice-to-have. Your assessor doesn’t need to visit the plot to do the SAP calculation, but they do need your set of building plans. If you lose your plans, there’s no way you can get your SAP Calculations done – compare it to a trying to pass your driving test without any wheels on your car. A no starter.

Maybe you do have building plans but your labourer, Jack, spilt his brew all over them. Half of the lines on the page are indistinguishable and one of the corners has been ripped off in Jack’s frantic rush to dry the papers off. Your assessor might be able to make do, but if he bodges it up it could prove very costly further down the line.

What to do in case of lost or damaged plans? Get in touch with your local permit agency or records office. They’ll tell you what info you need to provide to get copies of the existing blueprints then have Jack pick them up to make amends.

Be On Time

If we receive your set of plans halfway through a build, there’s not a great deal we can do to change the energy performance of that building. Situations like this also lead to much bad practice and more than often, the installation of expensive unsuitable technologies added in hindsight just to meet a planning condition or pass building regs. Starting late really is a killer.

How to avoid this? You guessed it, start early! The earlier the better. If you’re working with your SAP assessor before planning has been submitted, it’s the ideal situation and the one which allows the highest chance of success. You should never engage with a SAP assessor after building regs applications.

Assess the Assessor

So, you have your set of plans and you’ve not submitted your planning yet, time to get in touch with a SAP assessor. You’ll surely pass the SAP test, right? Not quite.While there are a whole host of factors that can make a building fail its SAP test, the biggest of them summed up already in this article, the one that’s often most overlooked is the assessor. It’s vital to stick to ATTMA-accredited assessors with some failsafe references,  like us nice folk at Purple Energy. Go for someone cheaper than us and it’s likely they’ll be cowboys. Cowboys can blag the talk but if you end up failing your SAP test, and your building won’t be marketable as a result – it could be hugely costly.


SAP calculations can be confusing; very rarely black and white, the reasons one building will pass and another will fail are often difficult even for us to explain. However, make sure you have a decent set of plans and get in touch with a quality assessor early enough in the process, and your chances of passing will rocket.

If there is anything you feel unclear about or you simply want to speak to one of our team members, don’t hesitate to give our office a call.