Whole house retrofits are a proven way to upgrade older, fuel inefficient buildings. At the heart of them is the fabric first approach, which prioritises improving the building envelope to boost thermal efficiency. This article explains the strategy, why it matters, and what to consider when planning a project.
Understanding whole house retrofits
Whole house retrofits upgrade existing buildings to improve energy efficiency, comfort and lifespan. Unlike piecemeal improvements, they treat the building as one system, considering how each measure affects the others, including moisture and ventilation. The goal is to significantly reduce energy consumption and carbon emissions, creating healthier and more sustainable homes.
What is meant by a fabric first approach
In building design, fabric refers to the materials and components used to construct a building: walls, floors, roofs, windows, doors and other structural components. It covers the physical materials such as brick, timber, concrete and steel, finishes such as plaster, paint and tiles, and the elements that determine performance, including insulation, air barriers and vapour barriers.
A fabric first approach prioritises the building envelope to create a high performance, energy efficient building. It treats the fabric as the primary means of reducing energy consumption rather than relying on mechanical or electrical systems. That requires a full assessment of how the building performs before any technology is added. Reduce the heat a building loses first, and any new heating system can be smaller, cheaper to run and more effective.
Adopting a fabric first approach instead of treating issues in isolation, like replacing a heating system without considering insulation, promotes long term energy savings by addressing the root causes of inefficiencies.
Brendan Collum, Founder and Managing Director, IRS Construction
Fabric optimisation
Fabric optimisation is the process of designing and choosing building materials and components to create a structure that is both efficient and effective, balancing cost, performance and sustainability. It matters for three reasons.
It reduces the environmental impact of a building by minimising resource use and waste. Choosing sustainable, durable and energy efficient materials produces a structure with a lower carbon footprint.
It improves performance: lower energy consumption, better thermal comfort and, with the right ventilation in place, better indoor air quality. Well insulated, airtight construction cuts the energy needed for heating, and that adds up to real savings over time.
It makes the building more cost effective to run. Materials that are affordable, durable and easy to maintain produce buildings that are safe, comfortable and practical for the people living in them.
Three reasons to take a fabric first approach to retrofit
Energy efficiency
Improved insulation and airtightness lower energy demand, cutting heating costs and making bills more manageable for occupants.
Comfort
Better thermal performance creates a stable indoor climate, reducing draughts, cold spots and temperature swings.
Sustainability targets
Lower energy use means lower bills and lower carbon emissions, both of which energy performance standards and funding programmes measure.
Techniques used in fabric first retrofits
Insulation upgrades
Insulation added to walls, roofs and floors, chosen for thermal performance, moisture behaviour and fire safety. Non-combustible mineral wool is widely used. On the external walls of taller residential buildings, non-combustible materials (Class A1 or A2) are a legal requirement: for buildings with a storey at 18 metres or more in England and Wales, and over 11 metres in Scotland. Choosing the right product for the building is part of the design, not an afterthought.
Airtight construction
Gaps, cracks and junctions sealed with airtightness membranes, tapes, sealants and draught-proofing. Less air leakage improves thermal performance and comfort at the same time. It must be paired with a planned ventilation strategy, so moisture can still escape and condensation and mould are avoided.
Advanced glazing
Energy efficient windows using double or triple glazing, low emissivity coatings, argon or krypton gas fills and thermally broken frames. Against single glazing, they keep far more heat in during winter and, with the right specification, help limit overheating in summer.
Delivering a retrofit properly
Assessment and coordination. A Retrofit Coordinator oversees a full assessment of the building, including its condition, ventilation and any heritage significance, identifying energy saving opportunities and risks. This is what informed decisions are built on.
Detailed design. A plan that addresses insulation, airtightness and ventilation together, so every part of the envelope is considered as one system, set within a medium term improvement plan so each stage of work supports the next.
Installation. Skilled installers with the training to implement best practice. Precision here is what turns a good design into a building that performs.
Quality assurance testing. Checks that validate the installation against the performance criteria, rather than assuming it met them.
Commissioning and handover. Final adjustments to verify every measure works in harmony, and clear handover so residents know how to get the best from their home. Monitoring and evaluation then confirm the building delivers what the design promised.
Selecting contractors certified to PAS 2030:2023, working within the PAS 2035:2023 whole house retrofit framework, gives confidence in the outcome. Both standards, alongside TrustMark registration, are required for government funded schemes such as ECO.
A well designed building envelope can improve thermal comfort by reducing draughts, cold spots and overheating, creating a healthier indoor environment by improving air quality, reducing the infiltration of outdoor pollutants and minimising the growth of mould and mildew.
Brendan Collum, Founder and Managing Director, IRS Construction
The challenges in older buildings
Older buildings were constructed for appearance, cost and function rather than energy performance. Materials were chosen for availability, durability and price, not thermal efficiency. The result is buildings that need more energy to heat, often with minimal insulation and significant heat loss. Higher bills, lower comfort, more carbon.
Typically they have single glazed windows that lose heat and let in noise and draughts; air leaks around windows, doors and other openings creating cold spots; solid or uninsulated walls that lose heat quickly; ventilation that relies on uncontrolled air leakage, which must be replaced by a planned ventilation strategy once the building is made more airtight; architectural constraints that limit how much insulation and sealing can be added; and, where the building is listed or historically significant, the need to improve efficiency without damaging its character.
Fabric first in an older building is therefore harder. Detailed assessment and a solution designed for that specific structure, rather than a standard package, is what makes it work. And because the carbon used in the original construction has already been spent, upgrading an existing building is usually the lower carbon choice compared with demolition and rebuild.
IRS Construction
Specialist façade remediation and retrofit contractor. Established 2013.