If you're planning an extension or conversion to your property, it's important to bear in mind the amount of glazing used and whether this exceeds government regulations, as this may mean that you need to get SAP calculations completed. If you're on the hunt for a specialist team that can take care of this for you, Falcon Energy are your answer. With many years of experience and a professional, dedicated team of experts, we guarantee great service, extensive knowledge and speedy results.

What are Excess Glazing Calculations?

With new extensions or conversions to a property, there's a limit to the amount of glazing permitted. You're restricted to 25% of glazing to floor area and if you exceed this limit, you must have proper and professional justification. This is due to glazing and openings losing more heat than walls, making it less energy efficient.

With many extensions these days having far more glazing on elements to let in more light, sticking to the 25% limit can be difficult. Excess Glazing Calculations can successfully prove your need for extra glazing and help keep your building project on track and on budget.

If it's deemed that your new extension or conversion exceeds regulations in terms of glazing, the Building Control Officer will ask to see official Excess Glazing Calculations that must demonstrate either:

  • Area weighted U-value method
  • Full SAP calculation to include the existing property

The first option is typically suited for property renovations that only accrue a small amount of excess glazing which, in turn, shows the thermal elements could potentially be improved elsewhere to compensate.

Should the total percentage of excess glazing be recorded as higher, a full SAP calculation is required that must also take into account your existing property. This assesses the overall energy performance of your home, taking into account building materials and heating systems. Depending on the results, the rest of your current property may be taken into account and it may be suggested that upgrades elsewhere would successfully offset any additional glazing needed for the new build.

What is required for Excess Glazing Calculations?

In order for us to undertake excess glazing calculations accurately and efficiently, we need the following details from you:

  • Construction drawings to scale
  • Existing and proposed floor plans
  • Existing and proposed elevations
  • Any heating systems to be used
  • Any renewable energy sources (such as solar panels)
  • Existing and proposed sections
  • Site location

We will use all of this information to put the calculations together and understand how your extension will impact the efficiency of your home, if at all.

How can Falcon Energy help?

At Falcon Energy, not only do we have years of experience at providing Excess Glazing and SAP calculations but we also pride ourselves on outstanding customer service and fantastic, speedy results. We know that time is often of the essence in extension or conversion cases and are keen to keep your project on time and budget. We'll work hard to complete the work as quickly as possible, without compromising quality, and are locally based in Horsham, West Sussex meaning we could get to you sooner than you think. We work throughout Sussex, Surrey, Kent and London.

Frequently Asked Questions

Why do extensions and conversions need SAP Calculations?

Extensions and conversions alter the design and plan of a property and can therefore, impact on its overall energy efficiency and CO2 emissions. By assessing the extension or conversion, this can be offset to keep your current rating.

Specifically, all extensions that have glazing that is equivalent to more than 25% of the total floor area of the extension will need to be tested.


Is the entire house assessed or just the extension?

There may be times when the whole property needs to be assessed alongside the extension, but typically only the floor, walls and roof of the extension itself will need to be assessed as part of extension and conversion SAP calculations.

An instance where the whole property would be assessed is where heat loss from the extension’s glazed areas cannot be offset by improvements made to the extension alone, for example altering the thermal efficiency of the floor.


What is involved?

Our team of fully trained assessors create an energy model including the plans of the extension or conversion and calculate predicted annual CO2 emissions. Plans can then be made for glazing and insulation to meet the standards of the Building Regulations SAP requirements.

Once the work is completed, we will carry out tests to ensure the energy efficiency is as expected and will work to save you money and add value to your property.


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Call us now for a no obligation quote

Our team at Falcon Energy are here to help and would love to offer you a free, no obligation quote for your SAPs and Excess Glazing Calculation needs. Just call us today on 01403 253439 or email info@falconenergy.co.uk and we'll be happy to help.