PAS 2035

BORN FROM PAST FAILURES

Developed by the British Standards Institution, PAS 2035underpins the UK’s net zero strategy by ensuring retrofit projects are designed and delivered in a consistent, high quality and accountable way.

It was introduced following the Each Home Counts Review, which identified wide spread issues with poor installations, limited accountability and a lack of consumer protection. of a div block.

THE WHOLE HOUSE WAY

PAS 2035 requires a whole house approach, assessing the dwelling’s construction, condition, ventilation strategy and occupancy before any measures are designed.

This prevents the problems often seen in past retrofit work, such as damp, mould and inadequate ventilation, and ensures measures work together as an integrated system.

PERFORMANCE WITH A PURPOSE

The framework emphasises indoor environmental quality, measure durability and long-term building performance, helping ensure retrofits avoid unintended consequences and remain effective over the building’s life.

PAS 2035 is mandatory for many government-funded schemes, including ECO and Warm Homes, making it central to the UK’s retrofit standards framework and a key driver in cutting carbon emissions and fuel poverty.

PAS 2035
RETROFIT ROLES

Retrofit Advisor
Provides early guidance to households, explaining retrofit options, funding routes and the overall process. They help residents understand potential improvements, expected benefits and any risks, ensuring informed decisions before assessments, design or installation begin.
Retrofit Assessor
Carries out the on site assessment, gathering detailed data on the building’s condition, occupancy, energy performance and heritage sensitivity. They record measurements, photographs and risk factors to inform accurate design, coordination and overall project planning in line with PAS 2035.
Retrofit Coordinator
Oversees the entire project from assessment to completion. They manage risk, quality and compliance, develop the improvement plan, liaise with residents and project teams, review evidence and ensure all documentation is accurate, complete and lodged with TrustMark.
Retrofit Designer
Develops technical designs and specifications for each measure using assessment data to create practical, safe solutions. They consider energy performance, heat loss, thermal bridging, moisture, structural integrity and heritage significance to ensure measures compatible and in-line with PAS 2035, Building Regulations and best practice.
Retrofit Installer
Installs energy efficiency measures such as insulation, new windows, heating systems or renewables. Installers must hold PAS 2030 certification and follow design specifications, quality standards and safety requirements to deliver compliant, durable and effective improvements.
Retrofit Evaluator
Monitors and evaluates post-installation performance to confirm whether the retrofit project has achieved its intended outcomes. They analyse energy use, indoor conditions and resident feedback, and highlight any shortfalls or issues so lessons can be fed back into future projects.

THE RETROFIT PROCESS

1

PROPERTY SELECTION

Client identifies properties for the retrofit program

RETROFIT ASSESSMENT

Assessment completed and recorded

2

3

Technical Survey

Installer completes survey and uploads required documents to PAS Hub

Pre-Coordination

Retrofit Coordinator appointed and instructed

4

5

Retrofit Design

Design prepared in line with assessment findings and PAS requirements

6

Document Approval

Retrofit Coordinator reviews and approves design, technical survey & pre-installation documents

7

Installation Instruction

Installer authorised to proceed with works

8

Installation
& Evidence

Works completed. Installer uploads mid and post installation evidence. *Site visits completed where necessary

9

Post-Installation Audit

Retrofit Coordinator audits evidence & paper work

→Any remedials issued → Installer completes & re-uploads to PAS Hub.

10

Final
Review

Retrofit Coordinator completes final compliance check

11

TrustMark
Lodgement

Project lodged with Trustmark if compliant

12

Compliance Confirmation

Letter of compliance issued to client

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