The need for retrofit

Government has committed to achieving Net Zero emissions by 2050 and so there is an urgent need  for the energy efficiency of our building stock to be upgraded. Currently, around 50% of emissions come from our buildings, many of which were built at a time when construction did not include insulation, draught proofing or efficient building services.

While some of the  stock can be easily upgraded, traditional and historic properties can be more challenging because they were designed to work in a different way – they are permeable / breathable, as opposed to impermeable / sealed. Specialist knowledge of traditional properties is required if these are to be upgraded. In some cases, the risk of upgrading an elements is just too high and may lead to damp, rot, and poor indoor air quality. The PAS 2035 (domestic) and PAS 2038 (non-domestic) regulations provide a framework for ensuring that the risks are properly assessed and understood so that we can upgrade our architectural heritage without harming it and provide healthy environments for occupants. In general, a whole building, fabric-first approach is advocated.

The PAS 2035 retrofit standard

PAS 2035 can be used for any domestic retrofit projects that are funded by: 

  • national or local government schemes
  • landlords or social housing organisations
  • individual homeowners / occupants

The standards apply to retrofit work carried out by building contractors and specialist installers as well as local builders and independent trades people.

As an Architect, Domestic Energy Assessor (DEA), Retrofit Assessor and Retrofit Co-ordinator with additional qualifications in older and traditional buildings, I am qualified under PAS 2035 to carry out all of the professional roles:

  • Retrofit Assessor
  • Retrofit Co-ordinator
  • Retrofit Designer
  • Retrofit Evaluator

Since I specialise in historic building conservation and sustainability, you can be assured that you will have a knowledgeable and experienced professional on the team who will work to balance  client requirements with the  need to safeguard our architectural heritage and lessen our impact on the environment.

The PAS 2038 retrofit standard

PAS 2038 applies to the retrofit of energy efficiency measures (EEMs) in non-domestics buildings, including retrofit change of use projects and internal fit-outs.

As with PAS 2035, the standards apply to work carried out by building contractors and specialist installers as well as local builders and independent trades people. 

I am qualified to work on PAS 2038 projects as an Architect and Retrofit Lead Professional. As with PAS 2035, my qualifications allow me to work on historic properties.

How I can work with you

I work with homeowners, landlords (including social housing landlords) and installers of energy efficiency measures (EEMs).

If you are a homeowner or landlord, you can appoint me directly and I will provide a service tailored to your individual requirements. This is the best way to co-ordinate your project as early appointment means I can provide impartial advice before you have committed to a particular product / suite of products and an installer. I will work with you and other team members (if you have appointed others) to consider all of the options available to you – I am not selling a product so if the evidence suggests a lesser intervention is appropriate, then  that is what I will advise, design, co-ordinate and evaluate.

If you are an installer or EEMs, I can work with you on a project-by-project basis or as a longer term appointment.  I will  liaise closely with your teams so that I have a detailed knowledge of the products you install,  and I will ensure that all aspects of the retrofit process are carried out successfully.

Client protection

Domestic Energy Assessments

While most people know about Domestic Energy Assessments in the context of selling or renting houses, the Energy Performance Certificates (EPC) that are produced, are the basis for retrofit projects under PAS 2035. Knowing the current energy performance rating of a domestic property is mandatory for funded projects, but even if you are paying for a retrofit project yourself, you may find it to be a useful starting point as it is a cost-effective way to determine the energy efficiency of your home and understand which energy saving measures might bring the biggest benefit.

The process begins with a survey of your home so that its construction can be modelled using RdSAP software. This will be done very carefully to ensure that the results are reliable – it does take time, particularly with properties that are large, have different types of construction (e.g. a combination of solid and suspended floors and some parts of the property with a basement or open porch; or varying storey numbers, roof types and rooms in the roof).  You should note  that the modelling has to be evidence-based, which means that construction and services (e.g. existing insulation) will only be modelled in the software if they can be seen or there is sufficient documentary evidence to prove that they are there. Despite EPCs providing a ‘worst-case-scenario’ homeowners should remember that they are just a starting point and the rest of the retrofit process will ensure that proposals for improving energy efficiency will be tailored to the home and its occupants.

These assessments can be undertaken for sale / rental as well as for retrofit.

Retrofit Assessments

A retrofit assessment is a much more detailed assessment of a property that goes sufficient depth that the design of the energy efficiency measures can be undertaken and the project can be coordinated . It includes:

  • identification of the location, orientation, and context
  • appraisal of the dwelling’s heritage, architectural features, structure, construction and condition, and the building services. Note that the basic appraisal will not be suitable for all tradition / historic buildings and a full heritage statement may be required (see Retrofit Design below)
  • identification of any local planning authority constraints
  • identification of construction or structural defects including the presences of condensation and/or mould growth
  • identification of any energy efficiency measures already installed or proposed
  • inspection and review of the existing ventilation
  • appraisal of the dwelling’s construction and the suitability of the dwelling for improvement
  •  measured survey in accordance with RdSAP conventions and PAS 2035
  • identification of site constraints imposed by the site, e.g. elevation and exposure, access, party walls, rights of light, consideration of adjoining properties;
  • identification and characteristics of the installed building services
  • occupancy assessment
  • additional information that might have an impact on the retrofit project now and in the future.

Retrofit Co-ordination

The Retrofit Coordination involves oversight of work carried out by other professionals and installers on the project team, as well as carrying out specific technical tasks. These include:

  • creating an Improvement Options Evaluation (IOE) to identify an appropriate package of EEMs. The evaluation will provide a calculation of the simple payback period for each individual energy efficiency measure (EEM),  the carbon cost-effectiveness of each measure, and the simple payback and carbon cost-effectiveness of any suggested or proposed package of measures
  • preparing a report of the IOE and identifying a recommended package of EEMs to form the basis of a medium‑term improvement plan 
  • preparing a monitoring and evaluation plan that is appropriate for all proposed EEMs in the medium-term improvement plan
  • verifying that the EEMs to be included in the domestic retrofit project are included in the design and specification prepared by a Retrofit Designer
  • advising the client on the need for any statutory, health and safety or ecological approvals for the proposed retrofit work, and then either make the necessary applications or ensure that they are made by others
  • providing the complete retrofit design to the Retrofit Installer for costing and subsequent installation, and checking that the information is sufficient;
  • providing the Retrofit Installer with the retrofit assessment
  • providing the Retrofit Installer with briefings relevant to the design and installation
  • collecting and reporting on evidence that the requirements of PAS 2035 have been met during the installation (e.g. by site inspection)
  • informing the Retrofit Installer of any non-compliant work and agreeing a timetable and quality for rectification
  • updating the IOE and medium‑term improvement plan in accordance with the retrofit design at the end of the project
  • retaining copies of project documentation (e.g. test certificates and commissioning records, operation and maintenance instructions, warranties)
  • recommending that  a new or updated EPC is prepared post-handover
  • providing the client with a new or updated medium‑term improvement plan 

Retrofit Design

The retrofit design process follows the requirements set out in PAS 2035, as well as being in accordance with the RIBA Plan of Work.  Activities include:

  • reviewing the retrofit assessment to confirm that the information included is sufficient for a retrofit design
  • reviewing the report of IOE, the medium‑term improvement plan and the EEMs with the client, and agreeing the measures to be included in the project
  • preparing a detailed / technical design and specification information about the proposed EEMs and ventilation strategy, and develop an airtightness and air leakage testing strategy
  • applying for any necessary statutory approvals where this is not being undertaken by the Retrofit Coordinator or other specialists
  • producing a heritage impact assessment following BS 7913 (where applicable)
See Architecture and Heritage Consultancy for full details of the services offered.

Retrofit Evaluation

Each project will be evaluated at a basic level upon completion, however there is a requirement for more in-depth evaluation if problems have been identified (e.g the energy savings have not been realised). These more detailed evaluations are carried out by an Retrofit Evaluator who has not been involved in the project, so it is possible to appoint me at just this stage for a completed project carried out with other retrofit professionals.

Evaluation will be tailored to the particular project and will take account of the original project objectives. 

If an evaluation is required outside of the PAS 2035 process, a Building Performance Evaluation may be more appropriate as this can incorporate a much wider scope.