0.1 About CarbonLite Retrofit (CLR)

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What is CarbonLite Retrofit?

AECB CarbonLite™  Retrofit (CLR) is the latest addition to the AECB CarbonLite family. The original CarbonLite Programme (CLP) focuses on new buildings. Now, CarbonLite Retrofit provides knowledge that is specific to retrofit.

There are two elements to CarbonLite Retrofit:

  1. AECB CarbonLite™ Retrofit Online Training Course
  2. AECB CarbonLite ™ Retrofit Coordination Training Course –  see here for more details

However, the CLR course is not just for those overseeing retrofit projects, as explained below.

1. CarbonLite Retrofit Online Training Course

Central to CarbonLite Retrofit are three key principles:

  • Heating energy should be used much more efficiently while at the same time
  • Comfort should increase, and
  • Health of occupants and of building fabric should be protected and enhanced.

It is also important that each retrofit is conceived as part of a larger system: that of the regional and national building stock – supplied by a heat and power system that needs to match supply and demand during a very challenging decarbonisation transition between now and 2050. Other factors such as: embodied carbon emissions from new build and retrofit activity; the required levels of retrofit to support national heat and power decarbonisation trajectories, are being explored by the AECB, working with the Passivhaus Trust, LETI and the modelling team at the National Grid (see their  Future Energy Scenarios*).

1.1 Course Content

By completing the CLR course, participants will learn:

  • Why a moisture-robust, fabric-first approach to low energy retrofit is beneficial
  • How to achieve it

The aim is to enable retrofitters to achieve improved buildings that enjoy:

  • A future-proofed increase in winter and summer internal comfort levels
  • Excellent indoor air quality
  • Low running costs with a minimal energy performance gap
  • Retrofit strategies that are ‘economically optimised’ for owners and occupants
  • CO2 savings at low to negative cost per tonne of CO2 saved
  • Avoidance or reduction of risks from unintended consequences related to moisture

The diagram below shows the key themes covered in the course. Participants will learn how building fabric, building services and the UK climate combine to affect the balance of heat and moisture in our homes. This in turn affects the health of the building and the health and comfort of the occupants. Every aspect has an associated cost or cost benefit.

CLR overview summary diagram (Source: Tina Holt)
CLR overview summary diagram (Source: Tina Holt)

1.2 CLR course structure

The course is divided into 8 Modules (in addition to this one – Module 0), and each Module contains a number of lessons.

Every lesson contains text, images and links to further reading. Most lessons will have quiz questions at the end for participants to check their level of understanding.

Graphs, diagrams and photographs of construction details (such as the photos below) are used throughout.

We will be adding update notes to various lessons during 2022  to indicate areas where the course material will be updated in line with changes to our understanding of best retrofit practice, changes to building regulations and in line with current and planned changes to the UK heat and power supply system and energy security.


1.3 Undertaking the CarbonLite Retrofit course gives:

  • Access to the AECB online retrofit training course and quiz style exam platform
  • Access to retrofit practitioner communities to share with and learn from others via discussion, project monitoring, analysis and case studies
  • Guidance on space heat demand reduction targets for retrofit and involvement in developing these into Retrofit Energy Standards
  • Access to the AECB Knowledgebase, an online searchable resource of several hundred articles
  • Encouragement to add your projects to and compare them with others on the Low Energy Building Database.

The CLR training course is also part of a programme of research to increase theoretical and practical understanding of how to safely improve the performance of the UK’s existing buildings. By engaging in the programme, and monitoring and sharing results, all CLR participants will be able to contribute to the development of better low energy retrofit.

1.4 Who is CLR for?

CLR contains information for everyone involved in retrofitting. However, the focus of different professions will vary and some will need to go into more detail than others.

  • Design & construction professionals
  • Building owners
  • Builders
  • Trades
  • Property Managers
  • Building Control and Planning Officers
  • Energy consultants
  • Manufacturers
  • Policy & decision makers

1.5 Policy Note

CarbonLite Retrofit has been designed with the UK’s current and future green house gas (GHG) emissions targets in mind.

Space Heating demand has been a focus for much AECB work in recent years due to the inherently difficult and long term nature of this sector in reducing GHG emissions and improving the health and wellbeing of citizens. If we were aiming to achieve a space heating reduction of 50% across the entire UK dwelling stock, some properties will need to cut space heating consumption by up to 80% to compensate for others that for good reasons are not so easy to retrofit. Ironically, the so-called “hard-to-treat” homes are those where dramatic reductions of up to 80% can be most achievable. The 50% figure has been a working assumption for the AECB for several years, and ongoing dwelling stock analysis work may further inform this, we discuss this later in the course.

Generally then, the CLR approach focuses on retrofit activity that would achieve reductions of around 50%-80%  in space heating demand and associated GHG emissions. Guidance on heating energy targets can be downloaded from the course, based on both PHPP and SAP modelling. Other AECB building standards (Energy, Water, Daylighting & Whole Life Carbon) can be accessed via the AECB Building Standards menu item here. .

Lesson tags: AECB, CarbonLite Retrofit, CarbonLite Retrofit certification, CLR, CLR certification, fabric first, low carbon retrofit, low energy retrofit, moisture robust retrofit
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