Whole House Plans: What They Are and Who Writes One

A whole house plan is a single document that sets out every energy improvement a home needs, in the right order, over several years. It covers the building fabric (walls, windows, floors and roofs), the heating system, ventilation and, where possible, renewable energy, and it comes with impartial, scientific recommendations, detailed costings, architectural drawings and scheduling options¹. The idea exists because doing measures one at a time, without a plan, risks spending money in the wrong order: insulating a wall before fixing ventilation, or buying a heat pump before the fabric is ready.

The plan is not a new invention. The UK's retrofit standards framework, PAS 2035, introduced in 2019, requires the production of longer-term retrofit plans and promotes a whole-house approach specifically to reduce the risk of detrimental consequences for the health and comfort of residents². In practice, a plan is produced by a trained Retrofit Assessor who surveys the home, and a qualified Retrofit Coordinator who manages the project and turns the assessment into a staged programme⁴.

The headline figures: the plan itself is sometimes in the range of £750¹. The work it recommends is a far bigger commitment: the average cost of retrofitting an individual home, such as to install a low carbon heating system and energy efficiency measures, is just under £15,000⁶, and one established whole house plan service reported an average project value of around £25,000⁷. Deep whole-house retrofit can reduce energy use and carbon emissions by as much as 80 per cent⁸.

Inside a whole house plan

At its core, the plan is a survey plus a programme. The survey side records the condition and construction of the building: the fabric, the existing heating system, how the home is ventilated, and where energy is being lost. The programme side turns that into recommendations, sequenced so that each measure supports the next.

The scope is deliberately broad. Deep whole-house retrofit aims to improve the building fabric (walls, windows, floors and roofs), the heating system, and to install renewable energy where possible⁸. A plan covering only one of these, such as insulation alone, is not a whole house plan; the term implies all three domains are considered together, with ventilation treated as a first-order concern rather than an afterthought.

What the householder receives varies by service, but the fuller versions include impartial, scientific recommendations with detailed costings, architectural drawings and scheduling options¹. A tailored Whole House Plan from a one-stop-shop service documents a variety of energy efficiency measures and outlines the costs and carbon savings⁵. Council-backed services can go further still: the Homewise service in Bridgend, for example, offers a personalised home energy action plan with an indicative EPC rating and a breakdown of the cost for any work and potential savings¹⁰.

The staged character matters as much as the content. PAS 2035 requires the production of longer-term retrofit plans, which means the document is written to be delivered over years, not weeks². That is what distinguishes it from a one-off home energy assessment, which tells you where the home stands today, or an EPC recommendation report, which lists possible measures without sequencing them into a coherent programme.

Who can produce one

Two roles do the work, both defined by PAS 2035, which is the overarching UK retrofit standards framework¹¹. A Retrofit Assessor carries out the assessment of the home, identifying appropriate energy efficiency measures⁵. A qualified Retrofit Coordinator then manages the project; under PAS 2035, a retrofit has to be managed by a qualified Retrofit Coordinator⁴. The two roles are covered in more detail on retrofit assessors and retrofit coordinators.

The framework covers the whole life cycle of a retrofit project, from the initial engagement with a client, through the assessment, design, installation and subsequent evaluation and monitoring stages¹². So the people who write the plan are the same people, or at least the same framework of people, who oversee its delivery.

There are extra requirements for older buildings. For traditional or historic buildings, PAS 2035 mandates adherence to BS 7913, the guide to the conservation of historic buildings; these projects are typically categorised as high-risk and require professionals to hold specialised qualifications, such as the ABBE Level 3 Award in Energy Efficiency and Retrofit of Traditional Buildings⁴.

One weakness in the framework is worth knowing about. A 2026 report from the Committee of Public Accounts found that retrofit assessors and retrofit coordinators can be appointed and contracted by the installer they are assessing, and the Department agreed there is not enough independence between these roles under PAS 2035¹³. A householder wanting genuine independence in the plan can ask who employs the assessor and coordinator, and whether they have any connection to the firms who would carry out the work.

In practice, named professionals do this work. In the Stoke Climsland Carbon Zero Homes project in Cornwall, retrofit assessments and whole house plans were carried out by Paul Willingham of Two Counties Property Surveyors, and 45 retrofit assessments and whole house plans were completed under that project¹⁴.

Costs and commitments at a glance

The plan document itself is the cheap part. Welsh Government guidance on green energy choices describes the whole house plan option as the most expensive option, sometimes in the range of £750¹. That figure is a guide to the survey-and-plan stage only, and prices are provider-quoted; no published range beyond that is available.

The work the plan recommends is where the money goes. The average cost of retrofitting an individual home, such as to install a low carbon heating system and energy efficiency measures, is just under £15,000⁶. At Cosy Homes Oxfordshire, a service that has been running whole house retrofit projects since 2019, the minimum project value served was £10,000 and the average project value was around £25,000⁷.

A cost that surprises many households is enabling and repair work: the fixing of damp, rot or structural problems that must be dealt with before insulation can go in. A sample of 14 whole house retrofit projects showed that enabling and repair works on average accounted for 26 per cent of total costs, and actual enabling costs were far higher than estimated at the outset, at roughly £1,600 to £3,000 per property⁹. This is a strong argument for the assessment stage: finding these problems on paper before they are found by installers mid-project.

Against those costs sits the potential return. Deep whole-house retrofit can deliver reductions in energy use and carbon emissions of as much as 80 per cent⁸. The full cost picture, including how these figures vary by property type, is set out on what a whole-house retrofit costs in the UK.

Why households take them up

The best evidence on why households do or do not commission a whole house plan comes from consumer research commissioned by UKGBC, conducted via in-depth interviews in December 2020 with 10 homeowners across England who were either considering or had already undertaken measures to improve energy efficiency¹⁵.

The findings point to three drivers. First, most householders are attracted to the idea of a whole house plan once it is explained to them, especially the benefits of knowing upfront how to sequence measures and ensure forward compatibility¹⁶. A feeling of future proofing is appealing to householders¹⁶: the plan's value is not just the work it schedules but the dead ends it prevents.

Second, householders' decisions are strongly affected by the length of time they expect to stay in their current home¹⁵. A household planning to move in two years weighs a staged programme very differently from one planning to stay for twenty. Third, those contemplating more extensive works indicate they would willingly pay for the service¹⁵, which suggests the plan is seen as worth buying precisely by the households facing the biggest projects.

The research also found a perception problem worth naming. Householders surveyed categorised measures according to three stages of a whole house retrofit journey, with a perception that benefits decline as costs increase¹⁵. In other words, the expensive later stages, such as heat pumps and renewables, are seen as delivering less obvious benefit per pound than early fabric work. A good plan addresses this directly by showing what each stage delivers on its own terms.

Availability in England, Scotland, Wales and Northern Ireland

Where a household can actually get a whole house plan depends heavily on where it lives. The biggest gap in retrofit advice provision in Great Britain is in England, where only parts of the country have access to local services, meaning overall provision is inconsistent¹⁷. The Climate Change Committee and its partners have recommended that England needs a comprehensive home energy retrofit scheme¹⁸, and a 2019 parliamentary inquiry found a profound disparity between the public money invested in residential energy efficiency schemes per capita in England compared to the devolved nations¹⁹.

Scotland has more consistent structures. Scottish Government policy supports whole house retrofits: over the five years from 2021, it committed to delivering an increasing number of whole house retrofits to fuel poor households with a zero emissions first approach²⁰. Scotland also has the Home Report, a document required when selling a property, which is intended to give sellers an incentive to carry out repairs before marketing their properties²¹. Advice routes are covered on free home energy advice in Scotland.

Wales has the Optimised RetroFit Programme, a whole house, pragmatic approach to decarbonising existing homes which sets out a route to net zero for each home²². Welsh Government analysis goes further, arguing that holistic retrofit of all homes should be a priority, not just those rated EPC D to G²³. Advice routes are on free home energy advice in Wales.

England's provision is patchwork: regional pilots and council services fill some gaps, and the free home energy advice in England page maps what exists. Northern Ireland has its own advice line, covered on NI Energy Advice. The practical consequence is that two identical houses either side of a border can face very different access to whole house plan services.

PAS 2035, building regulations and planning rules

PAS 2035 is the rulebook. Introduced in 2019 as a clear framework for best practice in the energy retrofit of domestic properties, it covers the entire energy efficiency retrofit process in homes, from initial assessment and design to installation and evaluation, and incorporates the updated PAS 2030 installer standard³. It is already referenced in the current version of the Approved Document as a means to assess background ventilation in an existing dwelling, and that reference will be retained in the 2026 edition²⁵. Government delivery guidance keeps pace: ECO4 guidance has updated its references from PAS 2035:2019 to PAS 2035:2023 throughout²⁶.

Where does compliance actually bind? PAS 2035 is required for a small number of cases, such as high-rise buildings and buildings that are both protected and traditionally constructed². But publicly funded schemes can impose it more widely: the West Midlands Combined Authority's devolved retrofit pilot requires all domestic retrofit installations to comply with appropriate safety and construction standards, including PAS 2035/2030:2023²⁷.

Planning is a separate question. Most retrofit measures do not require full planning permission, but some do, and this depends on the type of property and its location²⁸. Roof alterations are a common example: householder or full planning permission is required in England if the limits and conditions are not met, or if permitted development rights have been removed in the area²⁹. Some councils publish checklists intended to help householders know which energy efficiency and renewable energy measures can be installed without the need to submit a planning application³⁰.

The rules also reach into quality assurance. Scotland's heat and buildings quality assurance statement notes that the PAS 2035/2030:2019 standard covers the entire energy efficiency retrofit process in homes, from initial assessment and design to installation and evaluation²⁴. And the independence flaw noted above, where assessors and coordinators can be contracted by the installer they assess, is a live regulatory concern acknowledged by the Department¹³.

Sources of plans: commercial and community options

The clearest working example of a whole house plan service is Cosy Homes Oxfordshire, a one-stop shop home eco-retrofit service designed to support the homeowner from the beginning to the end of their eco-retrofit journey⁵. It launched in early 2019, delivered by the Low Carbon Hub and RetrofitWorks, with the National Energy Foundation helping establish the scheme during a two-year pilot phase funded by BEIS that ended in March 2021⁵. It now continues without grant funding, aiming to become a self-sustaining business for delivering whole house retrofit projects⁵.

Its process shows the shape of a whole house plan service end to end:

1. A Retrofit Coordinator or Energy Assessor visits and conducts an assessment of the home to identify appropriate energy efficiency measures⁵.
2. The recommendations are formulated into a tailored Whole House Plan that documents the measures and outlines the costs and carbon savings⁵.
3. An independent Retrofit Coordinator keeps a check on the quality of the service throughout⁵.
4. The homeowner gains access to a pool of trusted contractors, vetted and rigorously assessed by the RetrofitWorks team⁵.

Homeowners or landlords in Oxfordshire can start with the free Plan Builder tool on the Cosy Homes Oxfordshire website³¹. Its first two years are documented in detail: over 550 homeowners had registered by March 2021, with around 50 on a waiting list for their initial home assessment; the planned customer journey assumed eight weeks between registering and deciding which measures to go ahead with⁷. The service's rental strand was largely unsuccessful, and the biggest barrier was the readiness of the supply chain for retrofit in Oxfordshire to work in a coordinated way⁷.

Other routes exist. Cornwall's Stoke Climsland Carbon Zero Homes project delivered 45 retrofit assessments and whole house plans through a named local surveyor¹⁴. The West Midlands Combined Authority's Buildings Retrofit Pilot is aimed at retrofitting homes and public buildings to drive the transition to net zero, healthy and sustainable buildings across the region³². In Wales, the Development Bank of Wales runs Green Homes Wales, and Bridgend council's Homewise service offers a tailored retrofit action plan with an indicative EPC rating and cost breakdown¹⁰. The idea itself has long roots: as far back as 2010, the Committee on Climate Change recommended a national energy efficiency programme involving a whole house approach, assisting homeowners with insulating their houses alongside the proposed Pay as you Save scheme³³.

Evidence on results

The evidence on completed whole house retrofits is still thin, and honest pages say so. A 2024 Retrofit Revisit by CIBSE examined ten completed retrofit projects, of which nine were houses and one was a flat³⁴. That sample size says most of what is confidently known about outcomes comes from small numbers of monitored projects, not from a large statistical base.

What the monitored work does show is substantial. Deep whole-house retrofit, covering fabric, heating and renewables, can deliver reductions in energy use and carbon emissions of as much as 80 per cent⁸. Against that stands the cost evidence: enabling works running at 26 per cent of total costs and far above early estimates⁹, and average retrofit costs of just under £15,000 per home⁶.

The scale of the national task frames all of it. Existing UK homes will all need to be retrofitted³⁵, and one analysis of a programme to provide whole house retrofit for 9 million homes calculated that the UK would need to retrofit, on average, one home every thirty-five seconds between now and 2050⁸. The workforce is not yet there: retrofitting the UK's homes will require at least 100,000 more trained workers⁶. For the individual householder, this is the context behind waiting lists and supply-chain readiness problems reported by services on the ground⁷.

Whole house plans and your energy self sufficiency

Retrofitting means making changes to existing buildings to reduce energy use and therefore carbon emissions²⁸. Done as a whole house programme, its intended outcomes are to permanently reduce energy bills, improve energy security and cut carbon emissions¹⁷. For a household, that is the independence case in one sentence: less energy needed per degree of warmth, and therefore less exposure to prices set elsewhere.

The 80 per cent reduction figure is the upper bound of what deep whole-house retrofit can deliver⁸. A home that reaches anything close to it needs dramatically less bought energy, and the renewable element of a plan, where the site allows it, replaces some of what remains with generation the household owns. The plan is also the mechanism for keeping that route open: sequencing fabric before heat pump, and heat pump before renewables, is what forward compatibility means in practice¹⁶.

The dependence that remains should be stated as firmly as the benefit. A whole house plan does not remove the grid, a supplier, or the installers and manufacturers behind the measures; it reduces how much of each the home needs. The plan document itself depends on the competence and independence of the people writing it, and the framework's independence flaw means that dependence is real enough for a parliamentary committee to have flagged it¹³. And the delivery depends on a supply chain that, by the sector's own account, is not yet ready to work in a coordinated way at scale⁷.

The most energy-independent step in the whole process may be the cheapest one: the assessment. Knowing what the home needs, in what order, is what stops a household buying the wrong measure at the wrong time, and that knowledge keeps its value even if the work is staged over a decade. The pages on planning a route to household energy independence and what order energy improvements should be done in pick up from here.