26th January 2021
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Tips for achieving a high SAP assessment rating

Whether you’re looking to construct a new residential building, conversion will require SAP Calculations to be carried out. These SAP assessments will then be used to create a rating which will contribute towards an energy performance certificate.

Achieving a higher rating on an SAP Assessment and Energy Performance Certificate can lead to an increase in the property’s value, so there are rewards to achieving an high SAP rating.

Nowadays, starting work before you have a design is challenging. Whereas in the past, architects and developers all but ignored SAP rating, changes to SAP in 2005, 2009 and 2014, now ensure that SAP regulatory compliance is much tougher to attain.

Unsurprisingly, given the current climate crisis, and resultant EU and UK environmental policies, control of CO2 emission targets have tightened enormously. A typical new build designed just 5 years ago would be likely to achieve a lower SAP rating by the standards of today’s regulations.

One of the most common FAQs on this subject is, ‘Why do some builds fail and others pass?’ There’s no easy answer, but a variety of factors can contribute to a rejection: Boiler size, for example. Or a non-compliant wall junction. Even the thickness of floor insulation on a floor, or the direction in which a house points!

Some factors lie beyond client control – if a dwelling has no connection to mains gas; for example, the owners might have to use oil or gas. Fossil fuels cost more and generate significant CO2 emissions, and because Target Emission Rates are based on mains gas, you may lose out.

SAP tips from SAP experts

As highly experienced assessors in the field of SAP calculation, we are experienced enough to recognise what works in the real world. And arguably more importantly, what doesn’t work at all. We make SAP calculations every day — encompassing anything from one-off self-builds to multi-story tower blocks.

Setting aside the weighty considerations of climate change, and agreeing that our goal is not to create the zero-carbon home, we can identify the following rules of thumb:

Set high energy efficiency targets

We believe that minimum values represent targets to be smashed. Provided the dwelling has well-insulated fabric, renewable technologies will not be needed to see you through, so feel free to incorporate as much floor, roof and wall insulation as you can.

A significant amount of heat is lost through windows and doors

Watch the value of ‘u’ on any openings you specify, lowering them as much as you can. A development Aim for 1.4 W/m2K or under.

It’s the controls — don’t blame the boiler

Zonal heating and boiler load compensators often impact significantly more on the SAP rating than primary systems.

Make it airtight

Every new build requires Air Permeability Tests on completion, with the final figure input to the SAP calculations. The envelope should be sealed and execute a pre-test check.

Consider the impact of thermal bridging

Thermal bridging is heat loss that leaks out through areas where external walls meet. Schemes like Accredited Construction Details (ACD’s) avoid the need for default figures. See our guide to thermal bridging.

Consult a trusted expert on how to improve

Spending time looking at designs for ways to improve them can sometimes yield little results, so having a trusted SAP expert to act as a fresh pair of eyes can allow you to spot energy efficiency improvements. 

We are passionate about delivering extra value in our SAP assessments to help identify opportunities to improve energy efficiency and raise the value of a development. Contact us for a bespoke quote and we can help you save up to £800 per plot.

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